---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 02/12/07: 37 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:56 AM - Mag & Starter Switches (Bill Denton) 2. 06:04 AM - Re: Mag & Starter Switches (JOHN TIPTON) 3. 07:20 AM - Re: Mag & Starter Switches (Hinde, Frank George (Corvallis)) 4. 07:24 AM - 24V resistive load on 12V system? (Dr. Andrew Elliott) 5. 07:30 AM - Re: Mag & Starter Switches (Robert L. Nuckolls, III) 6. 07:58 AM - Re: 24V resistive load on 12V system? (Robert L. Nuckolls, III) 7. 08:00 AM - Re: 24V resistive load on 12V system? (Hinde, Frank George (Corvallis)) 8. 08:12 AM - Re: Attaching Shield to "Lo"/Ground Wire at Intercom (Bill Steer) 9. 08:27 AM - Re: Attaching Shield to "Lo"/Ground Wire at Intercom (Robert L. Nuckolls, III) 10. 08:34 AM - Re: Attaching Shield to "Lo"/Ground Wire at Intercom (Robert L. Nuckolls, III) 11. 09:15 AM - Re: Attaching Shield to "Lo"/Ground Wire at Intercom (With CORRECTED LINK) (Robert L. Nuckolls, III) 12. 09:32 AM - Re: ELT Antenna (Robert L. Nuckolls, III) 13. 10:02 AM - Re: Re: Attaching Shield to "Lo"/Ground Wire at Intercom (RV_10) 14. 11:43 AM - Re: Mag & Starter Switches (C Smith) 15. 12:01 PM - Correct resistor for 12v LED (Don Mack) 16. 12:04 PM - Battery Tenders as recharging tools . . . (Robert L. Nuckolls, III) 17. 12:19 PM - Re: Correct resistor for 12v LED (john@ballofshame.com) 18. 12:23 PM - Re: Correct resistor for 12v LED (john@ballofshame.com) 19. 12:23 PM - Theft deterrent . . . (Robert L. Nuckolls, III) 20. 12:25 PM - Re: Correct resistor for 12v LED (Bob White) 21. 12:39 PM - Re: Theft deterrent . . . (john@ballofshame.com) 22. 12:51 PM - Re: Correct resistor for 12v LED (Matt Prather) 23. 12:59 PM - Re: Theft deterrent . . . (rtitsworth) 24. 01:09 PM - Re: Theft deterrent . . . (Robert L. Nuckolls, III) 25. 01:20 PM - ICOM Hand-Held Antenna Adapter (Robert L. Nuckolls, III) 26. 02:43 PM - Re: ICOM Hand-Held Antenna Adapter (Dave N6030X) 27. 02:45 PM - Re: Mag & Starter Switches (Dave N6030X) 28. 03:41 PM - Re: Mag & Starter Switches (Matt Prather) 29. 03:42 PM - Re: Mag & Starter Switches (Robert L. Nuckolls, III) 30. 03:49 PM - Shunt vs hall effect sensor (Don Owens) 31. 04:43 PM - Re: Shunt vs hall effect sensor (Robert L. Nuckolls, III) 32. 05:07 PM - Re: Shunt vs hall effect sensor (Allen Fulmer) 33. 05:48 PM - Re: Shunt vs hall effect sensor (Robert L. Nuckolls, III) 34. 06:43 PM - Re: Start switch () 35. 07:14 PM - Suppressor Devices for Relay Coils () 36. 08:37 PM - Re: Battery Tenders as recharging tools . . . (Kelly McMullen) 37. 10:21 PM - Re: Battery Tenders as recharging tools . . . (Dave N6030X) ________________________________ Message 1 _____________________________________ Time: 05:56:23 AM PST US Subject: AeroElectric-List: Mag & Starter Switches From: "Bill Denton" I have noticed that some aircraft use two separate toggle switches for the magnetos and a pushbutton for the starter, and that some aircraft use an automobile-like key-operated mag and starter switch. Obviously the toggle/pb arrangement would allow you to use the starter to turn the engine over with the mags off. Outside of this, are there any other advantages/disadvantages to one arrangement over the other? Given post-9/11 security considerations, do airport operators prefer/require the key-lockable system? Do insurors have an preference? Thanks! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=94438#94438 ________________________________ Message 2 _____________________________________ Time: 06:04:39 AM PST US From: "JOHN TIPTON" Subject: Re: AeroElectric-List: Mag & Starter Switches Don't forget you can have a keyed, left right both, and a separate starter button/switch John ----- Original Message ----- From: "Bill Denton" Sent: Monday, February 12, 2007 1:54 PM Subject: AeroElectric-List: Mag & Starter Switches > > > I have noticed that some aircraft use two separate toggle switches for the > magnetos and a pushbutton for the starter, and that some aircraft use an > automobile-like key-operated mag and starter switch. > > Obviously the toggle/pb arrangement would allow you to use the starter to > turn the engine over with the mags off. > > Outside of this, are there any other advantages/disadvantages to one > arrangement over the other? > > Given post-9/11 security considerations, do airport operators > prefer/require the key-lockable system? > > Do insurors have an preference? > > Thanks! > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=94438#94438 > > > ________________________________ Message 3 _____________________________________ Time: 07:20:35 AM PST US Subject: RE: AeroElectric-List: Mag & Starter Switches From: "Hinde, Frank George (Corvallis)" Yes the on/off/both keyswitch is a single point of failure for both ignitions and good redunadancy planning will have you seperating that function into 2 separate switches. This is an experimental aircraft there are no requirements for key lockable systems and insurers don't care, although if I were an insurer I would want two independent switches. Frank -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Bill Denton Sent: Monday, February 12, 2007 5:55 AM Subject: AeroElectric-List: Mag & Starter Switches --> I have noticed that some aircraft use two separate toggle switches for the magnetos and a pushbutton for the starter, and that some aircraft use an automobile-like key-operated mag and starter switch. Obviously the toggle/pb arrangement would allow you to use the starter to turn the engine over with the mags off. Outside of this, are there any other advantages/disadvantages to one arrangement over the other? Given post-9/11 security considerations, do airport operators prefer/require the key-lockable system? Do insurors have an preference? Thanks! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=94438#94438 ________________________________ Message 4 _____________________________________ Time: 07:24:18 AM PST US From: "Dr. Andrew Elliott" Subject: AeroElectric-List: 24V resistive load on 12V system? I want to make sure I understand this properly. Please advise if I have made some conceptual errors. I have a heated pitot tube designed for a 24V system. It is supposed to draw 8 amps at 24V. This makes its fixed resistance, according to Ohms' Law: R = V/I = 24/8 = 3 Ohms So if I install this pitot tube in a 12V system, it should draw only 4 amps: I = V/R = 12/3 = 4 A But, it will only work at about 1/2 the heat level it had in the 24V system. I can measure the stabilized temperature rise, but how hot should it have to get to be usable in the 12V system? I am thinking that since I don't have any anti-ice on the plane, I never fly in the clouds when the OAT is below freezing, so that if I can get a 25=B0C rise from the tube, I should be OK. Yes? I am *guessing* that the AN-spec 24V tube was designed heat from -56=B0C, the nominal temp above 36K', and that 1/2 the rated power should work fine, while also saving me some current draw. Thoughts? Andy Elliott, Mesa, AZ N601GE (reserved) 601XL/TD/QB, Corvair, building... ________________________________ Message 5 _____________________________________ Time: 07:30:40 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Mag & Starter Switches At 05:54 AM 2/12/2007 -0800, you wrote: > >I have noticed that some aircraft use two separate toggle switches for the >magnetos and a pushbutton for the starter, and that some aircraft use an >automobile-like key-operated mag and starter switch. Only single engine airplanes. Key-switches are the brainchild of marketing folks back in the 40s and early 50s that were trying to get the airplane to look as much as possible like an automobile. Has more to do with market appeal than convenience or security. >Obviously the toggle/pb arrangement would allow you to use the starter to >turn the engine over with the mags off. > >Outside of this, are there any other advantages/disadvantages to one >arrangement over the other? Toggles and push buttons are less expensive and fit on the panel in nice rows with the other switches. See: http://www.aeroelectric.com/PPS/Switch_Panels/Switches.pdf >Given post-9/11 security considerations, do airport operators >prefer/require the key-lockable system? Anything with two engines uses switches. Once you're in the cabin, you've got the airplane. Key-switches offer very little security. Lost my keys once on a rental airplane. Broke the wires off the mags by reaching through the oil filler door. Hand propped the airplane and brought it home. >Do insurors have an preference? If you want a modicum of security, consider this http://www.aeroelectric.com/Pictures/Misc/AC_Theft_Protection.jpg It's out where everyone can see it . . . a thief is unlikely to work on it out in the open. The locks on key-switches are exceedingly simple. My kid can pick one in a minute or so. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 6 _____________________________________ Time: 07:58:37 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 24V resistive load on 12V system? At 08:16 AM 2/12/2007 -0700, you wrote: >I want to make sure I understand this properly. Please advise if I have >made some conceptual errors. > >I have a heated pitot tube designed for a 24V system. It is supposed to >draw 8 amps at 24V. This makes its fixed resistance, according to Ohms' Law: > > R = V/I = 24/8 = 3 Ohms > >So if I install this pitot tube in a 12V system, it should draw only 4 amps: > > I = V/R = 12/3 = 4 A > >But, it will only work at about 1/2 the heat level it had in the 24V system. Actually, 1/4th the heat . . . or a bit more. What you need to do is hook your tube up to a 14V power supply and stir it in a bath of crushed ice and water. Measure current after it stabilizes - this may take a minute or so. Pitot tubes have a strong positive temperature coefficient of resistance. Here's some data I plotted off a batch of tubes a few years ago. http://www.aeroelectric.com/Pictures/Curves/Pitot_Heater_R_Plot.pdf When you drop the voltage, not only does current go down by 1/2, so does applied voltage . . . therefore the resulting power is 1/4 that of the 28v operation. > >I can measure the stabilized temperature rise, but how hot should it have >to get to be usable in the 12V system? I am thinking that since I don't >have any anti-ice on the plane, I never fly in the clouds when the OAT is >below freezing, so that if I can get a 25C rise from the tube, I should >be OK. Yes? > >I am *guessing* that the AN-spec 24V tube was designed heat from -56C, >the nominal temp above 36K', and that 1/2 the rated power should work >fine, while also saving me some current draw. Keep in mind that the goal for a de-ice system is to melt ice. When super-cooled water hits your pitot tube, the energy in the tube has to overcome the heat-of- crystalization. Know that heated pitot tubes are a match in a big dark room when it comes to flying in an icing environment. Any heat is better than no heat . . . but running a 28v tube on 14v is waaayyyy down on the efficacy curve for "any heat". Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 7 _____________________________________ Time: 08:00:47 AM PST US Subject: RE: AeroElectric-List: 24V resistive load on 12V system? From: "Hinde, Frank George (Corvallis)" Heating effect is P=I*I*R Thus in your 28V system P= 8*8*3 = 192 Watts In your 12V system P= 4*4*3 = 48 Watts Thus in a 12 system the same pitot only produces a quarter of the 24V's heating effect. As Heating effect is proportional to the change in temperature for two identical mass flow situations then the temp rise will only be 25% of what it was previously. Now do you even need a heated Pitot?..Highly debatable even in an IFR platform and I assume you intend your Zodiac as a VFR machine?...If so then you certainly don't need a heated pitot. Frank ________________________________ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Dr. Andrew Elliott Sent: Monday, February 12, 2007 7:17 AM Subject: AeroElectric-List: 24V resistive load on 12V system? I want to make sure I understand this properly. Please advise if I have made some conceptual errors. I have a heated pitot tube designed for a 24V system. It is supposed to draw 8 amps at 24V. This makes its fixed resistance, according to Ohms' Law: R = V/I = 24/8 = 3 Ohms So if I install this pitot tube in a 12V system, it should draw only 4 amps: I = V/R = 12/3 = 4 A But, it will only work at about 1/2 the heat level it had in the 24V system. I can measure the stabilized temperature rise, but how hot should it have to get to be usable in the 12V system? I am thinking that since I don't have any anti-ice on the plane, I never fly in the clouds when the OAT is below freezing, so that if I can get a 25=B0C rise from the tube, I should be OK. Yes? I am *guessing* that the AN-spec 24V tube was designed heat from -56=B0C, the nominal temp above 36K', and that 1/2 the rated power should work fine, while also saving me some current draw. Thoughts? Andy Elliott, Mesa, AZ N601GE (reserved) 601XL/TD/QB, Corvair, building... ________________________________ Message 8 _____________________________________ Time: 08:12:11 AM PST US From: "Bill Steer" Subject: Re: AeroElectric-List: Attaching Shield to "Lo"/Ground Wire at Intercom I'm in the same situation. Bob had given me a link at one time for this, but I can't find it. Also can't find anything in the articles on Bob's web site. Please let me know if you get a response to this. Thanks very much.. Do not archive Bill Steer ----- Original Message ----- From: r falstad To: aeroelectric-list Sent: Saturday, February 10, 2007 9:44 PM Subject: AeroElectric-List: Attaching Shield to "Lo"/Ground Wire at Intercom The installation instructions for my PS Engineering PM1000II intercom show all shields for the mics and phones grounded to their corresponding "Lo" wires. I've looked at Bob's comic books and searched the collection of FAQs and couldn't find a way to do it. The wires will be crimped onto D-SUB pins so there is only room for one wire. (For intercom installation wiring diagram, see http://www.ps-engineering.com/docs/pm1000wiring_data.shtml) Can I "daisy chain" the shields as Bob shows in his "Shield Termination Techniques" comic book and ground them all to Ground Pin 1 (which goes to the "forest-of-tabs" ground block) rather than at each individual "Lo" wire pin? Or should each shield be individually grounded to its corresponding "Lo" wire? It seems I could create an uninsulated length (~0.3 in) before the end of the "Lo" wire and lightly solder the shield directly to the "Lo" wire, cover it with heatshrink and then crimp my D-Sub pin to the end of the "Lo" wire and insert it into the connector. Bob GlaStar ________________________________ Message 9 _____________________________________ Time: 08:27:21 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Attaching Shield to "Lo"/Ground Wire at Intercom At 11:10 AM 2/12/2007 -0500, you wrote: >I'm in the same situation. Bob had given me a link at one time for this, >but I can't find it. Also can't find anything in the articles on Bob's >web site. Please let me know if you get a response to this. > >Thanks very much.. > >Do not archive > >Bill Steer http://aeroelectric.com/articles/pigtail/pigtail.html ________________________________ Message 10 ____________________________________ Time: 08:34:52 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Attaching Shield to "Lo"/Ground Wire at Intercom At 08:44 PM 2/10/2007 -0600, you wrote: >The installation instructions for my PS Engineering PM1000II intercom show >all shields for the mics and phones grounded to their corresponding "Lo" >wires. I've looked at Bob's comic books and searched the collection of >FAQs and couldn't find a way to do it. The wires will be crimped onto >D-SUB pins so there is only room for one wire. > >(For intercom installation wiring diagram, >see >http://www.ps-engineering.com/docs/pm1000wiring_data.shtml) > >Can I "daisy chain" the shields as Bob shows in his "Shield Termination >Techniques" comic book and ground them all to Ground Pin 1 (which goes to >the "forest-of-tabs" ground block) rather than at each individual "Lo" >wire pin? > >Or should each shield be individually grounded to its corresponding "Lo" >wire? It seems I could create an uninsulated length (~0.3 in) before the >end of the "Lo" wire and lightly solder the shield directly to the "Lo" >wire, cover it with heatshrink and then crimp my D-Sub pin to the end of >the "Lo" wire and insert it into the connector. The diagram cited at: http://aeroelectric.com/articles/pigtail/pigtail.html is pretty busy. Virtually all of the shielded wires depicted can be reduced by one conductor inside the shield by using the shield as a signal conductor. For example, the AUX Headphone jack wired to pins 17 and 4 can be handled on a single shielded wire. Use the shield to provide continuity from pin 4 to the LO side of the headphone jack. This philosophy is illustrated in the wiring diagram pages of: http://www.aeroelectric.com/DIY/Audio_Isolation_Amplifier.pdf See: http://aeroelectric.com/articles/pigtail/pigtail.html for techniques used to attach one or more shields into a single wire and termination into a connector pin. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 11 ____________________________________ Time: 09:15:03 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: Attaching Shield to "Lo"/Ground Wire at Intercom (With CORRECTED LINK) At 10:34 AM 2/12/2007 -0600, you wrote: At 08:44 PM 2/10/2007 -0600, you wrote: The installation instructions for my PS Engineering PM1000II intercom show all shields for the mics and phones grounded to their corresponding "Lo" wires. I've looked at Bob's comic books and searched the collection of FAQs and couldn't find a way to do it. The wires will be crimped onto D-SUB pins so there is only room for one wire. (For intercom installation wiring diagram, see http://www.ps-engineering.com/docs/pm1000wiring_data.shtml) Can I "daisy chain" the shields as Bob shows in his "Shield Termination Techniques" comic book and ground them all to Ground Pin 1 (which goes to the "forest-of-tabs" ground block) rather than at each individual "Lo" wire pin? Or should each shield be individually grounded to its corresponding "Lo" wire? It seems I could create an uninsulated length (~0.3 in) before the end of the "Lo" wire and lightly solder the shield directly to the "Lo" wire, cover it with heatshrink and then crimp my D-Sub pin to the end of the "Lo" wire and insert it into the connector. The diagram cited at: http://www.ps-engineering.com/docs/PM1000_wiring_11922.pdf is pretty busy. Virtually all of the shielded wires depicted can be reduced by one conductor inside the shield by using the shield as a signal conductor. For example, the AUX Headphone jack wired to pins 17 and 4 can be handled on a single shielded wire. Use the shield to provide continuity from pin 4 to the LO side of the headphone jack. This philosophy is illustrated in the wiring diagram pages of: http://www.aeroelectric.com/DIY/Audio_Isolation_Amplifier.pdf See: http://aeroelectric.com/articles/pigtail/pigtail.html for techniques used to attach one or more shields into a single wire and termination into a connector pin. By the way, the shield pigtails comic book cited above has been updated to fix broken links. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- -- 6:50 PM -- incoming mail is certified Virus Free. Checked by AVG. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 12 ____________________________________ Time: 09:32:17 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: ELT Antenna At 09:30 PM 2/8/2007 -0500, you wrote: > >What is your current opinion of where the ELT antenna should be installed >on an RV-4? My ACK ELT is mounted on the upper shelf of the baggage >compartment. I am leaning toward mounting the antenna on the topside of >the turtle deck right behind the canopy. If you have a snappy location >that is better concealed I would like to know. The airplane is finished >and this is one of the small details I have left to complete. Most installations are done just ahead of the vertical fin. The idea is that the fin structure offers a modicum of protection from damage if the airplane comes to rest upside down. The location you propose would function just fine. >Also, what does the large molded rubber base do on the ELT antenna? Is it >a strain relief to keep the antenna from snapping off in the breeze at >200+ MPH? Does it cover something up like a coil or what ever? I want to >be able to trim this rubber off so I can possibly mount the antenna inside >the cabin. However I do not want to destroy the antenna by sawing off >something important. If you're a prone to genuflect before those with airs of authority, you don't want to modify the antenna in any way . . . I discovered a few months ago that ELTS are now qualified under the TSO as a set of components. Whether or not removing the rubber hurts performance will not matter to one who slices and dices regulations. Given the multi-frequency requirements for modern ELT transmitters, it is quite possible that the molded rubber base has some kind of electro-smarts built in. I don't think I'd mess with it. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 13 ____________________________________ Time: 10:02:15 AM PST US From: "RV_10" Subject: RE: AeroElectric-List: Re: Attaching Shield to "Lo"/Ground Wire at Intercom Is this what you are after? John Cleary -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of glaesers Sent: Sunday, 11 February 2007 3:46 PM Subject: AeroElectric-List: Re: Attaching Shield to "Lo"/Ground Wire at Intercom I took a solder-cup D-Sub female connector and soldered all the connectors together and soldered one wire which went to the common pin on the intercom. Then I put pins on all the shields and "Lo" wires and put them in a male connector. At one time Bob had an article that showed this, but I couldn't find it either. Dennis Glaeser RV7A ---------------------------------------------------------------------------- --------------------- The installation instructions for my PS Engineering PM1000II intercom show all shields for the mics and phones grounded to their corresponding "Lo" wires. I've looked at Bob's comic books and searched the collection of FAQs and couldn't find a way to do it. The wires will be crimped onto D-SUB pins so there is only room for one wire. ________________________________ Message 14 ____________________________________ Time: 11:43:26 AM PST US From: "C Smith" Subject: RE: AeroElectric-List: Mag & Starter Switches Or as in the case of current Cessna's, only 10 or 12 different cylinders in whole manufactured fleet. Collect 'em all and you can fly any Cessna.(this I learned from a Cessna sales person). Effective theft control covers 2 areas of interest. For the aircraft itself a good prop lock. The heavy chain and padlock is a deterrent only to casual thieves. A set of bolt cutters will take one off in a couple of seconds. With battery operated hand tools and grinding wheels only the toughest bar-type (AKA- the Club) with vending machine type pin tumblers will provide security in the difficulty in their removal. Of course the weight of the deterrent becomes an issue when traveling to airports away from home. Maybe the better tactic here would be an easily removed (yet not commonly available) part that would prevent the power plant from starting, yet not be easily figured out by a quick visual. Hidden fuel valves come to mind, but could lead to disaster to the owner if forgotten, and there is enough fuel left in the system to taxi/get air born. The second area of security is your cabin and much cherished avionics. Certainly a tamper proof locking system will delay entry, but to what extent? I favor the pin tumblers, but they can be picked as well, it's just another skill/tool the would be thief needs. I think a better approach to securing the cabin is hiding the locking mechanism in an unconventional way. An advantage enjoyed only by the OBAM group. It doesn't have to be the same one used in flight to hold canopy closed. Of course if the thief is desperate enough, they will smash the plexi-glass, but if they still can't get the normal doorway open, getting in and out is still a big problem. How and where you park probably matter as much as your hardware. Thieves want easy in-n-out and concealment of their efforts. Whereas the OBAM builder thinks in terms of (to quote the omnipotent Bob himself) "$TIME$" the thief thinks in terms of risk/effort/Time. Give him a tough puzzle and exposure to discovery. That brings to mind the recent story of a prop-locked plane stolen in Mexico right out from under the occupied tower. Sometimes you just can't win. Craig Smith -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Monday, February 12, 2007 10:30 AM Subject: Re: AeroElectric-List: Mag & Starter Switches --> >Do insurors have an preference? If you want a modicum of security, consider this http://www.aeroelectric.com/Pictures/Misc/AC_Theft_Protection.jpg It's out where everyone can see it . . . a thief is unlikely to work on it out in the open. The locks on key-switches are exceedingly simple. My kid can pick one in a minute or so. Bob . . . ________________________________ Message 15 ____________________________________ Time: 12:01:35 PM PST US From: "Don Mack" Subject: AeroElectric-List: Correct resistor for 12v LED I have several 12v, 12ma LEDs from Radio Shack (part 276-272)in my panel. According to the calculators (15V max Supply, 12V LED, 12ma), I need a 27.0kohms, 1/8w resistor. Two questions: 1) led.linear1.org reports "The wizard thinks your forward voltage spec is suspiciously high, but will proceed with the calculations.". The input voltage is listed as 12-16V, 12-20ma, so I ASSuME that the calculation is correct that it just does not recognize 12v LEDs? 2) Where do I find 1/8w resistors? Don Mack |don@dmack.net | dmack.net ________________________________ Message 16 ____________________________________ Time: 12:04:05 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Battery Tenders as recharging tools . . . As promised, I've finished the first experiment to look at the recharge characteristics of a Battery Tender. Take a look at: http://www.aeroelectric.com/Pictures/Curves/Battery_Tender_Recharge_1.jpg I thought I'd looked at the Battery Tender performance some time ago but data taken on this test suggests this is the first time . . . Note that the Battery Tender's 'size' is not a limiting factor for putting energy back into a battery. The battery's terminal voltage was climbing nicely at a rate commensurate with the device's output rating of about 0.8 amps. The surprise comes when the device switches from a charge to sustain mode at just under 14.0 volts! To put this in context, look at: http://www.aeroelectric.com/Pictures/Curves/schumacher_3.jpg Here we see a predictable rise in voltage as the battery's chemistry converts incoming energy into stored chemical energy. Note also that the rate-of-rise takes a decidedly upward inflection sometime after the voltage climbs past 14.4 volts. This is typical of most if not all rechargeable battery chemistries. This characteristic is used to send a signal to truly 'smart' chargers to announce a nearly full state of charge. In the case for the Schumacher charger, we see that the profile changes from constant current to constant voltage where the battery is held in this "top-off" mode for about 2 hours. After that time, the charger's output drops to the expected sustaining level of about 13.0 volts. Going back to the Battery Tender, we see that the recharge voltage never rises to the inflection point indicating that the battery is about full. Further, there's no dwell at some elevated top-off voltage. I'm discharging the battery again to measure how much snort the Battery Tender put back into the battery. I'll then recharge it again with the Schumacher charger and compare notes again. This early look-see at the data suggests that admonitions against using Battery Tenders as battery chargers is correct. The Battery Tender doesn't get the job done based on what we know of battery chemistry and the charging profiles suggested by other manufacturers. The complaints I'd heard about Battery Tenders was that they were "too small" . . . in fact they appear to be quite capable with respect to energy output levels. Instead, they are deficient in smarts necessary to (1) detect end of charge, (2) hold at some elevated top-off level for a reasonable length of time followed by (3) drop to a sustaining level that doesn't charge the battery and simply offsets the battery's internal self discharge currents. Watch this space . . . Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 17 ____________________________________ Time: 12:19:28 PM PST US Subject: Re: AeroElectric-List: Correct resistor for 12v LED From: john@ballofshame.com Well.... you probably put in 12V for the "forward" voltage. 12V should be the "source" voltage. Your forward voltage is the voltage across the LED when it's turned on. This voltage will never get much above 2V, or so (increasing the voltage will simply increase the current and eventually blow it up, though). It varies a bit depending on the color of the LED. You should be able to look it up somewhere online what your particular color needs. Hope this helps. -John www.ballofshame.com > > I have several 12v, 12ma LEDs from Radio Shack (part 276-272)in my panel. > According to the calculators (15V max Supply, 12V LED, 12ma), I need a > 27.0kohms, 1/8w resistor. Two questions: > > 1) led.linear1.org reports "The wizard thinks your forward voltage spec is > suspiciously high, but will proceed with the calculations.". The input > voltage is listed as 12-16V, 12-20ma, so I ASSuME that the calculation is > correct that it just does not recognize 12v LEDs? > > 2) Where do I find 1/8w resistors? > > Don Mack | don@dmack.net | dmack.net > > ________________________________ Message 18 ____________________________________ Time: 12:23:30 PM PST US Subject: Re: AeroElectric-List: Correct resistor for 12v LED From: john@ballofshame.com Ok...so I played with the calculator a bit (cool). How's this for convenient. Click on the question mark next to "forward voltage" and it will pop up a list of color vs. voltage. 1/8W resitors? Just use a 1/4W. -John www.ballofshame.com > > I have several 12v, 12ma LEDs from Radio Shack (part 276-272)in my panel. > According to the calculators (15V max Supply, 12V LED, 12ma), I need a > 27.0kohms, 1/8w resistor. Two questions: > > 1) led.linear1.org reports "The wizard thinks your forward voltage spec is > suspiciously high, but will proceed with the calculations.". The input > voltage is listed as 12-16V, 12-20ma, so I ASSuME that the calculation is > correct that it just does not recognize 12v LEDs? > > 2) Where do I find 1/8w resistors? > > Don Mack | don@dmack.net | dmack.net > > ________________________________ Message 19 ____________________________________ Time: 12:23:41 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Theft deterrent . . . At 02:42 PM 2/12/2007 -0500, you wrote: > > > >Or as in the case of current Cessna's, only 10 or 12 different cylinders in >whole manufactured fleet. Collect 'em all and you can fly any Cessna.(this I >learned from a Cessna sales person). > >Effective theft control covers 2 areas of interest. For the aircraft itself >a good prop lock. The heavy chain and padlock is a deterrent only to casual >thieves. A set of bolt cutters will take one off in a couple of seconds. Depends on the chain. It DOES need to be hardened chain and lock. These are materials you probably wont find at Home Depot. My dad used to run a locksmithing operation and he sold the locks and chains that could only compromised with grinding tools and then only at considerable labor (and risk of exposure). The locks used unsymmetrical, double cut keys with the damnedest broaching profile I've ever seen . . . well beyond the picking skills of most locksmiths and probably every thief. Thefts from county road maintenance tool boxes and loss of portable compressors stopped after a switch to materials that exceeded the thief's patience and resources. Bob . . . ________________________________ Message 20 ____________________________________ Time: 12:25:44 PM PST US From: Bob White Subject: Re: AeroElectric-List: Correct resistor for 12v LED Hi Don, If it's a 12V LED, the resistors are built in. Just connect them to your 12 V source. Going to 15V or so shouldn't hurt them but you could add a small resistor to make up the difference. Figure 3v at the 12 ma rating would be a 250 ohm resistor in series. Most LED's have an actual forward voltage of around 2V. Bob W. On Mon, 12 Feb 2007 13:59:15 -0600 "Don Mack" wrote: > > I have several 12v, 12ma LEDs from Radio Shack (part 276-272)in my panel. > According to the calculators (15V max Supply, 12V LED, 12ma), I need a > 27.0kohms, 1/8w resistor. Two questions: > > 1) led.linear1.org reports "The wizard thinks your forward voltage spec is > suspiciously high, but will proceed with the calculations.". The input > voltage is listed as 12-16V, 12-20ma, so I ASSuME that the calculation is > correct that it just does not recognize 12v LEDs? > > 2) Where do I find 1/8w resistors? > > Don Mack |don@dmack.net | dmack.net > > > > > > > -- N93BD - Rotary Powered BD-4 - http://www.bob-white.com First Flight: 11/23/2006 7:50AM - 2.4 Hours Total Time Cables for your rotary installation - http://www.roblinphoto.com/shop/ ________________________________ Message 21 ____________________________________ Time: 12:39:51 PM PST US Subject: Re: AeroElectric-List: Theft deterrent . . . From: john@ballofshame.com You're dad was a locksmith. Neat....Lock picking is one of my hobbies. Ever seen an ABLOY? I've never quite figured out how you would approach picking one of these suckers. http://www.abloyusa.com/ -John > > > At 02:42 PM 2/12/2007 -0500, you wrote: > >> >> >> >>Or as in the case of current Cessna's, only 10 or 12 different cylinders >> in >>whole manufactured fleet. Collect 'em all and you can fly any >> Cessna.(this I >>learned from a Cessna sales person). >> >>Effective theft control covers 2 areas of interest. For the aircraft >> itself >>a good prop lock. The heavy chain and padlock is a deterrent only to >> casual >>thieves. A set of bolt cutters will take one off in a couple of seconds. > > Depends on the chain. It DOES need to be hardened chain and > lock. These are materials you probably wont find at Home Depot. > My dad used to run a locksmithing operation and he sold the locks > and chains that could only compromised with grinding tools and > then only at considerable labor (and risk of exposure). The locks > used unsymmetrical, double cut keys with the damnedest broaching > profile I've ever seen . . . well beyond the picking skills of most > locksmiths and probably every thief. > > Thefts from county road maintenance tool boxes and loss of portable > compressors stopped after a switch to materials that exceeded the > thief's patience and resources. > > Bob . . . > > ________________________________ Message 22 ____________________________________ Time: 12:51:36 PM PST US Subject: Re: AeroElectric-List: Correct resistor for 12v LED From: "Matt Prather" I don't think there are _any_ LED's designed to use 12v supply directly to the diode (someone might prove me wrong). However, many electronics houses are selling LED illuminated lamp fixtures that include biasing resistors built into the package. The part number you listed appears to be one of these. It doesn't need any additional biasing to make it work in a 12V environment. In other words, the forward voltage spec the calculator expects is for a bare LED. You can get away with a 1/4th watt or 1/2 watt if those are easier to find (they will be). The only problem with using the larger rating is that they will be physically larger (bulkier). Regards, Matt- > > I have several 12v, 12ma LEDs from Radio Shack (part 276-272)in my panel. > According to the calculators (15V max Supply, 12V LED, 12ma), I need a > 27.0kohms, 1/8w resistor. Two questions: > > 1) led.linear1.org reports "The wizard thinks your forward voltage spec is > suspiciously high, but will proceed with the calculations.". The input > voltage is listed as 12-16V, 12-20ma, so I ASSuME that the calculation is > correct that it just does not recognize 12v LEDs? > > 2) Where do I find 1/8w resistors? > > Don Mack | don@dmack.net | dmack.net > > ________________________________ Message 23 ____________________________________ Time: 12:59:52 PM PST US From: "rtitsworth" Subject: RE: AeroElectric-List: Theft deterrent . . . Portable, battery powered, Dewalt cutoff saws "eat" hardened steel easily (Home Depot burglar supply). Thus, it's not about making things thief proof it's about making your things harder to steal than someone else's. i.e. you don't have to outrun the bears - only the other campers (grin). ________________________________ Message 24 ____________________________________ Time: 01:09:06 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Theft deterrent . . . At 12:38 PM 2/12/2007 -0800, you wrote: > >You're dad was a locksmith. Neat....Lock picking is one of my hobbies. >Ever seen an ABLOY? I've never quite figured out how you would approach >picking one of these suckers. > >http://www.abloyusa.com/ I don't know if it was that brand . . . I think I recall dad showing me a lock in American Locksmith that operated on a similar principal. A challenge no doubt. About 30 years ago I built an electronic lock for a customer where the "key" was a connector having a network of components under the backshell that were potted into place. A simple examination of the connector's exposed pins with any test equipment only yielded a confusing array of reactance values . . . no DC continuity existed between any pins. In fact, the networks were precision components used to set the operating frequency of two Wien-Bridge oscillators built into the receptacle that accepted the key connector. The same single shielded wire that carried the two signals back to the control panel carried DC power out to run the lock-oscillators. Even if one placed a 'scope on the interconnection wiring, the mixing of two frequencies made the pattern impossible to measure with anything other than an audio spectrum analyzer . . . not a tool that most thieves would have access to. Electronically it was a fairly busy circuit but easy to make robust. Never heard from the customer again and my "lock box" was visible on the outside of his building for a lot of years after I installed it . . . I'm guessing it did the job. The only other lock I built was a combination system that accepted inputs from a keyboard. This was a simple 4-digit lock but the system would ignore all inputs until the proper first digit was selected. It then took the next three digits to complete the sequence. The lock featured a 3-second time delay from receipt of proper sequence before electric latch was retracted. This allowed the operator to input a random sequence of digits in full view of anyone watching. You could put in as many digits as you liked while avoiding the first digit of the opening sequence. After entering the proper sequence, the operator continues to punch digits at random until the lock operated. He got a real buzz out of watching the confusion on the face of his observers. For all practical purposes, the "combination" was exceedingly long and never entered the same way twice! Bob . . . ________________________________ Message 25 ____________________________________ Time: 01:20:50 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: ICOM Hand-Held Antenna Adapter I've received the 5 units from EDMO. I drilled the rivets out of one and produced the following pictures: http://www.aeroelectric.com/Pictures/Antenna/ICOM_HH_Adapter_1.jpg http://www.aeroelectric.com/Pictures/Antenna/ICOM_HH_Adapter_2.jpg The construction is pretty much as expected. The patina on the surface of the closed-circuit jack does not suggest any special plating. The radio-to-adapter cable is nicely built. These are nicely built and certainly as good as anything one could build using this technology. I have more orders than I have devices to ship. I'll fill the first five orders received. I'm going to think about this one a bit . . . might toss the idea out to the Tacos-at-Connie's crowd. We've not had lunch together for several months. It's about time. I'll ask all the folks who have offered to pick these things up give us feedback on their experience. If they prove to be troublesome (and assuming the T@C meeting produces a "better idea") the alternative device will be used as a warranty backup to the ICOM product. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 26 ____________________________________ Time: 02:43:14 PM PST US From: Dave N6030X Subject: Re: AeroElectric-List: ICOM Hand-Held Antenna Adapter Bob, hand some of them out to ham operators who are VHF experimenters and ask for their evaluation. Dave Morris At 03:19 PM 2/12/2007, you wrote: > > >I've received the 5 units from EDMO. > >I drilled the rivets out of one and produced the following >pictures: > >http://www.aeroelectric.com/Pictures/Antenna/ICOM_HH_Adapter_1.jpg > >http://www.aeroelectric.com/Pictures/Antenna/ICOM_HH_Adapter_2.jpg > >The construction is pretty much as expected. The patina on >the surface of the closed-circuit jack does not suggest >any special plating. > >The radio-to-adapter cable is nicely built. > >These are nicely built and certainly as good as anything >one could build using this technology. I have more orders >than I have devices to ship. I'll fill the first five >orders received. > >I'm going to think about this one a bit . . . might toss >the idea out to the Tacos-at-Connie's crowd. We've not >had lunch together for several months. It's about time. > >I'll ask all the folks who have offered to pick these >things up give us feedback on their experience. If they >prove to be troublesome (and assuming the T@C meeting >produces a "better idea") the alternative device will >be used as a warranty backup to the ICOM product. > > > Bob . . . > > ---------------------------------------- > ( IF one aspires to be "world class", ) > ( what ever you do must be exercised ) > ( EVERY day . . . ) > ( R. L. Nuckolls III ) > ---------------------------------------- > > ________________________________ Message 27 ____________________________________ Time: 02:45:37 PM PST US From: Dave N6030X Subject: Re: AeroElectric-List: Mag & Starter Switches Isn't one of the BIGGEST features of the key switch the fact that it prevents you from trying to start the engine with the non-impulse coupler magneto activated? Dave Morris At 09:30 AM 2/12/2007, you wrote: > > >At 05:54 AM 2/12/2007 -0800, you wrote: > >> >>I have noticed that some aircraft use two separate toggle switches >>for the magnetos and a pushbutton for the starter, and that some >>aircraft use an automobile-like key-operated mag and starter switch. > > Only single engine airplanes. Key-switches are the > brainchild of marketing folks back in the 40s and early > 50s that were trying to get the airplane to look as much > as possible like an automobile. Has more to do with > market appeal than convenience or security. ________________________________ Message 28 ____________________________________ Time: 03:41:02 PM PST US Subject: Re: AeroElectric-List: Mag & Starter Switches From: "Matt Prather" That feature is fairly easily accomplished with toggle switch controlled mags and starter switches. See: http://www.aeroelectric.com/PPS/Engine/Ignition/TogMagSw.pdf I believe either of circuits shown does what you're looking for. The non-impulse magneto is shorted out when the right-hand magneto switch is in the position which allows energizing the starter contactor. Regards, Matt- > > > Isn't one of the BIGGEST features of the key switch the fact that it > prevents you from trying to start the engine with the non-impulse > coupler magneto activated? > > Dave Morris > > At 09:30 AM 2/12/2007, you wrote: >> >> >>At 05:54 AM 2/12/2007 -0800, you wrote: >> >>> >>> >>>I have noticed that some aircraft use two separate toggle switches >>>for the magnetos and a pushbutton for the starter, and that some >>>aircraft use an automobile-like key-operated mag and starter switch. >> >> Only single engine airplanes. Key-switches are the >> brainchild of marketing folks back in the 40s and early >> 50s that were trying to get the airplane to look as much >> as possible like an automobile. Has more to do with >> market appeal than convenience or security. > > ________________________________ Message 29 ____________________________________ Time: 03:42:20 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Mag & Starter Switches At 04:44 PM 2/12/2007 -0600, you wrote: > >Isn't one of the BIGGEST features of the key switch the fact that it >prevents you from trying to start the engine with the non-impulse coupler >magneto activated? it can be strapped to do that . . . and you can wire toggle switches to do the same thing . . . and the non-keyed dual magneto switch could do it too. See figure Z-27 of http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf Bob . . . ________________________________ Message 30 ____________________________________ Time: 03:49:51 PM PST US Subject: AeroElectric-List: Shunt vs hall effect sensor From: "Don Owens" Hi all, I've been following the Z-14 wiring schematic for my electrically dependent RV-7. I also plan to use GRT EFIS and their EIS system. Without looking far enough ahead I did a great job of installing shunts for the electrical load meters. Duh! Now I realize the the GRT EIS system uses hall effect sensors! Well, maybe having an always up load meter for each electrical system wouldn't be all that bad. Does anyone have a source for good quality load meters? Who would just rip out the shunts and go with the EIS hall effect system?? Can I read the load on each of my two systems with the EIS? Thanks in advance, Don Owens Read this topic online here: http://forums.matronics.com/viewtopic.php?p=94572#94572 ________________________________ Message 31 ____________________________________ Time: 04:43:06 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Shunt vs hall effect sensor At 03:49 PM 2/12/2007 -0800, you wrote: > >Hi all, > >I've been following the Z-14 wiring schematic for my electrically >dependent RV-7. I also plan to use GRT EFIS and their EIS system. Without >looking far enough ahead I did a great job of installing shunts for the >electrical load meters. Duh! Now I realize the the GRT EIS system uses >hall effect sensors! Well, maybe having an always up load meter for each >electrical system wouldn't be all that bad. Does anyone have a source for >good quality load meters? > >Who would just rip out the shunts and go with the EIS hall effect system?? >Can I read the load on each of my two systems with the EIS? You could pick up an extra hall-sensor and put a switch in to select which sensor was driving the glass . . . Alternatively, here's a loadmeter I build here from Triplett pivot and jewel movements: http://aeroelectric.com/Catalog/AEC/9007/AEC9007-700.pdf http://aeroelectric.com/Catalog/9007-120-1_Loadmeter.jpg Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 32 ____________________________________ Time: 05:07:57 PM PST US From: "Allen Fulmer" Subject: RE: AeroElectric-List: Shunt vs hall effect sensor But Bob! It's not digital! Bob wrote: Alternatively, here's a loadmeter I build here from Triplett pivot and jewel movements: http://aeroelectric.com/Catalog/AEC/9007/AEC9007-700.pdf http://aeroelectric.com/Catalog/9007-120-1_Loadmeter.jpg Bob . . . ________________________________ Message 33 ____________________________________ Time: 05:48:32 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Shunt vs hall effect sensor At 07:07 PM 2/12/2007 -0600, you wrote: > >But Bob! It's not digital! Yup . . . but it gets its power to operate directly from the drop in the shunt. There's still a pretty good demand for small steam gages if they're good. Had to give up on Westach but these are REAL d-a movements! I think we sold 25 ship sets of these since I put them in the catalog a year ago. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ---------------------------------------- ________________________________ Message 34 ____________________________________ Time: 06:43:41 PM PST US From: Subject: AeroElectric-List: Re: Start switch 2/12/2007 Hello Henry, Thank you for your input copied below. My initial analysis of the cyclic intermittent inadvertent starter engagement problem on my friend's Beechcraft Sierra was exactly as you described below -- there must have been some internal malfunction of the ignition / start switch that was permitting electricity to flow in a limited manner through that switch to the activating coil in the starter relay even though the ignition / start switch had not been activated in any way. He did not attempt to move the ignition / start switch into the "START" position in order to start the engine while the starter was cycling prematurely on its own because I knew that we were not going to fly with this kind of malfunction. (See below ##) My friend turned the aircraft over to a local FBO, who, with no apparent trouble shooting efforts, decided that the problem was being caused by a faulty starter relay and they ordered a new one. I won't bore you with all the gory details of the fumbling FBO ordering 3 different relays before they got one that they thought was the correct one -- acceptable to both Beechcraft and the FAA. The bill was paid and the aircraft turned over this morning to my friend so we could go flying. It would not start. The original problem had disappeared, but we heard only the repeated activation and deactivation of the starter relay solenoid with no electrical power getting to the starter when he went to the START position on the ignition / start switch. The FBO analyzed this as a low battery -- actually two 12 volt Gill batteries in series since this is a 24 volt system. Their solution was to bring out their jump start cart and we agreed to this, not to go flying, but so we could start the aircraft and taxi over to a different FBO. There was no 24 volt source on the cart that was compatible with either the Sierra's old time Beechcraft external power receptacle or an alligator clip type plug in adapter that my friend had purchased. So the batteries were removed from the aircraft and put on the FBO's battery charger in the shop. That is where the batteries are now (8:22 PM) and the airplane is tied down on the FBO's ramp. During the afternoon we carried the original starter relay over to a different FBO who applied 24 volts to the relay coil and, by listening and using a voltmeter while we were observing, determined that it worked fine. So, yes, there may be an intermittent malfunction within the starter ignition switch and we'll do our own trouble shooting on that issue when we get the airplane in our hands away from the first FBO. But there is still the possibility of some kind of intermittent hang up malfunction within the original starter relay that gave us the symptoms that started this whole fiasco. There are at least three people: Bob Nuckolls, The Beech Aero Club, and I who want to dissect that relay to see what gives, but the owner is deferring any dissection until potential issues with the first FBO are resolved -- did they waste all this time and money by not doing any basic trouble shooting? Was the problem only in the ignition / start switch from the very beginning? I'll keep you all posted. ## But here is the real point I want to make in this response to your posting after that rambling preamble: If one has a suspected malfunction, or a known malfunction in one's ignition / start switch like that owner operating the Cessna 172 in the Aviation Safety magazine letter to the editor, do not fly the airplane. A broken innards malfunction in the start portion of that switch could migrate bits and pieces to the magneto grounding contacts in that same switch -- and when that happens you could lose one or both of your magnetos. I found it incredible that the owner could continue to operate that airplane "over the last few years" with that dangerous inadvertent starter engagement malfunction and replace all those other parts: master relay, starter relay, battery, and battery box grounding strap, before hitting upon replacing the ignition / start switch which instantly solved his problem. To his credit he was willing to share his experience with the readers of Aviation Safety magazine. Thanks again for the opportunity to make the above point. OC -- The best investment we can make is to gather knowledge. PS: Yes, I do subscribe to Aviation Safety, and, yes I did receive the magazine and read that letter shortly after my friend gave the plane to the FBO for repair. The letter helped reinforce my initial analysis, but only hands on trouble shooting will give definitive answers. Hip shooting and random parts replacement is not the proper way to maintain an airplane. PPS: I am still OC. Nothing against Bobs, but I am not a Bob, have never been a Bob, and never intend to be a Bob. ----- Original Message ----- From: Sent: Monday, February 12, 2007 5:06 PM Subject: Start switch Bob, This is a follow on to your starter problem. For some strange reason I was not able to post it to the is months Aviation Safety"Lectric List". There is a letter in this months Aviation Safety mag. that describes your problem and the attempts to resolve it to a "T". This aircraft was a 172 that had, had several items replaced to no avail. It was only after he replaced the key starter switch that the problem of the starter engaging after the master was turned on that the problem went away. It does make sense that if interior parts of the starter part of the switch are worn or broken the switch could be on when it appears to be off. May not be your problem at all but it is one more thought. Regards Henry ________________________________ Message 35 ____________________________________ Time: 07:14:22 PM PST US From: Subject: AeroElectric-List: Suppressor Devices for Relay Coils 2/12/2007 For those readers interested in this subject there is a fairly explicit dissertation in the last four pages of this engineering data sheet: http://www.leachintl2.com/english/english1/vol1/properties/US7064-4653.pdf OC -- The best investment we can make is to gather knowledge. ________________________________ Message 36 ____________________________________ Time: 08:37:21 PM PST US From: Kelly McMullen Subject: Re: AeroElectric-List: Battery Tenders as recharging tools . . . Good data to have. Would be interesting to compare to the Battery Minder, which is similar in that it charges to around 14V at 1.33 amps, then cuts back to 13.6 to maintain. I've been playing with it on a 1 yr old CB35A, and a 7 year old CB35A that was dead when I started. Both now show fully charged electrolyte specific gravity. I alternate, a few days on each. Robert L. Nuckolls, III wrote: > > > As promised, I've finished the first experiment to look > at the recharge characteristics of a Battery Tender. Take > a look at: > > http://www.aeroelectric.com/Pictures/Curves/Battery_Tender_Recharge_1.jpg > > I thought I'd looked at the Battery Tender performance > some time ago but data taken on this test suggests this is > the first time . . . > > Note that the Battery Tender's 'size' is not a limiting factor > for putting energy back into a battery. The battery's terminal > voltage was climbing nicely at a rate commensurate with the > device's output rating of about 0.8 amps. > > The surprise comes when the device switches from a charge to > sustain mode at just under 14.0 volts! To put this in > context, look at: > > http://www.aeroelectric.com/Pictures/Curves/schumacher_3.jpg > > Here we see a predictable rise in voltage as the battery's > chemistry converts incoming energy into stored chemical energy. > Note also that the rate-of-rise takes a decidedly upward inflection > sometime after the voltage climbs past 14.4 volts. This is typical > of most if not all rechargeable battery chemistries. This > characteristic is used to send a signal to truly 'smart' chargers > to announce a nearly full state of charge. > > In the case for the Schumacher charger, we see that the profile > changes from constant current to constant voltage where the > battery is held in this "top-off" mode for about 2 hours. After > that time, the charger's output drops to the expected sustaining > level of about 13.0 volts. > > Going back to the Battery Tender, we see that the recharge voltage > never rises to the inflection point indicating that the battery > is about full. Further, there's no dwell at some elevated top-off > voltage. > > I'm discharging the battery again to measure how much snort the > Battery Tender put back into the battery. I'll then recharge it > again with the Schumacher charger and compare notes again. > > This early look-see at the data suggests that admonitions > against using Battery Tenders as battery chargers is correct. > The Battery Tender doesn't get the job done based on what > we know of battery chemistry and the charging profiles > suggested by other manufacturers. The complaints I'd heard about > Battery Tenders was that they were "too small" . . . in fact they > appear to be quite capable with respect to energy output levels. > Instead, they are deficient in smarts necessary to (1) detect end of > charge, (2) hold at some elevated top-off level for a reasonable > length of time followed by (3) drop to a sustaining level that > doesn't charge the battery and simply offsets the battery's internal > self discharge currents. > > Watch this space . . . > > > Bob . . . > > ---------------------------------------- > ( IF one aspires to be "world class", ) > ( what ever you do must be exercised ) > ( EVERY day . . . ) > ( R. L. Nuckolls III ) > ---------------------------------------- > > ________________________________ Message 37 ____________________________________ Time: 10:21:10 PM PST US From: Dave N6030X Subject: Re: AeroElectric-List: Battery Tenders as recharging tools . . . I have a Battery Minder on my Gill G-35 battery now too. Before I used it, my battery used to hover around 12.2V when the plane was shut down. I ran the battery nearly dead once trying to start the engine when the weather had dropped below 30 degrees. After using the Battery Minder on it for about 3 days, it fired the engine up on a 25 degree morning in only about 5 blades, and the battery sits at over 13V when the plane is shut down. Dave Morris At 10:35 PM 2/12/2007, you wrote: > >Good data to have. Would be interesting to compare to the Battery >Minder, which is similar in that it charges to around 14V at 1.33 >amps, then cuts back to 13.6 to maintain. I've been playing with it >on a 1 yr old CB35A, and a 7 year old CB35A that was dead when I >started. Both now show fully charged electrolyte specific gravity. I >alternate, a few days on each. > >Robert L. Nuckolls, III wrote: >> >> >>As promised, I've finished the first experiment to look >>at the recharge characteristics of a Battery Tender. Take >>a look at: >> >>http://www.aeroelectric.com/Pictures/Curves/Battery_Tender_Recharge_1.jpg >> >>I thought I'd looked at the Battery Tender performance >>some time ago but data taken on this test suggests this is >>the first time . . . >> >>Note that the Battery Tender's 'size' is not a limiting factor >>for putting energy back into a battery. The battery's terminal >>voltage was climbing nicely at a rate commensurate with the >>device's output rating of about 0.8 amps. >> >>The surprise comes when the device switches from a charge to >>sustain mode at just under 14.0 volts! To put this in >>context, look at: >> >>http://www.aeroelectric.com/Pictures/Curves/schumacher_3.jpg >> >>Here we see a predictable rise in voltage as the battery's >>chemistry converts incoming energy into stored chemical energy. >>Note also that the rate-of-rise takes a decidedly upward inflection >>sometime after the voltage climbs past 14.4 volts. This is typical >>of most if not all rechargeable battery chemistries. This >>characteristic is used to send a signal to truly 'smart' chargers >>to announce a nearly full state of charge. >> >>In the case for the Schumacher charger, we see that the profile >>changes from constant current to constant voltage where the >>battery is held in this "top-off" mode for about 2 hours. After >>that time, the charger's output drops to the expected sustaining >>level of about 13.0 volts. >> >>Going back to the Battery Tender, we see that the recharge voltage >>never rises to the inflection point indicating that the battery >>is about full. Further, there's no dwell at some elevated top-off >>voltage. >> >>I'm discharging the battery again to measure how much snort the >>Battery Tender put back into the battery. I'll then recharge it >>again with the Schumacher charger and compare notes again. >> >>This early look-see at the data suggests that admonitions >>against using Battery Tenders as battery chargers is correct. >>The Battery Tender doesn't get the job done based on what >>we know of battery chemistry and the charging profiles >>suggested by other manufacturers. The complaints I'd heard about >>Battery Tenders was that they were "too small" . . . in fact they >>appear to be quite capable with respect to energy output levels. >>Instead, they are deficient in smarts necessary to (1) detect end of >>charge, (2) hold at some elevated top-off level for a reasonable >>length of time followed by (3) drop to a sustaining level that >>doesn't charge the battery and simply offsets the battery's internal >>self discharge currents. >> >>Watch this space . . . >> >> >> >> >> Bob . . . >> >> ---------------------------------------- >> ( IF one aspires to be "world class", ) >> ( what ever you do must be exercised ) >> ( EVERY day . . . ) >> ( R. L. Nuckolls III ) >> ---------------------------------------- >> >> >> > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.