---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 03/05/06: 30 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:21 AM - Re: Soldering question--What am I doing wrong? (Greg@itmack) 2. 07:03 AM - Re: Backup battery - Lightspeed EI (Robert L. Nuckolls, III) 3. 07:29 AM - My bubble has burst . . . (Robert L. Nuckolls, III) 4. 07:41 AM - Re: Soldering question--What am I doing wrong? (Dan Beadle) 5. 08:09 AM - Attitude Gyro (Steve Glasgow) 6. 09:24 AM - Re: Re: Composite planes, Metallic paint, and Antennae (PTACKABURY@aol.com) 7. 09:57 AM - Re: Re: Backup battery - Lightspeed EI (J. Mcculley) 8. 10:41 AM - Re: My bubble has burst . . . (jerb) 9. 11:10 AM - Re: My bubble has burst . . . (Harold) 10. 01:15 PM - Re: My bubble has burst . . . (Robert L. Nuckolls, III) 11. 01:15 PM - Re: Re: Backup battery - Lightspeed EI (Robert L. Nuckolls, III) 12. 01:25 PM - Re: Re: Composite planes, Metallic paint, and Antennae (Robert L. Nuckolls, III) 13. 02:05 PM - Re: Re: Backup battery - Lightspeed EI (Brian Lloyd) 14. 02:07 PM - Re: Re: Backup battery - Lightspeed EI (Brian Lloyd) 15. 02:59 PM - Heated Pitot test (Brinker) 16. 03:28 PM - Re: Heated Pitot test (Brian Lloyd) 17. 03:52 PM - Zener Diodes and LEDs (Dennis Johnson) 18. 04:30 PM - Re: Zener Diodes and LEDs (Brian Lloyd) 19. 05:19 PM - Re: Zener Diodes and LEDs (Dan Beadle) 20. 05:27 PM - Re: Zener Diodes and LEDs (Richard E. Tasker) 21. 05:53 PM - Re: Zener Diodes and LEDs (Dan Beadle) 22. 06:34 PM - Followup to Zener/LED Question (Dennis Johnson) 23. 06:56 PM - Re: Followup to Zener/LED Question (Dan Beadle) 24. 07:29 PM - Re: Followup to Zener/LED Question (Richard E. Tasker) 25. 07:38 PM - Re: Followup to Zener/LED Question (Richard E. Tasker) 26. 08:02 PM - Re: Heated Pitot test (Charlie Kuss) 27. 08:02 PM - Re: Re: Backup battery - Lightspeed EI (Robert L. Nuckolls, III) 28. 08:42 PM - Re: Zener Diodes and LEDs (Malcolm Thomson) 29. 08:45 PM - Re: Re: Backup battery - Lightspeed EI (Brian Lloyd) 30. 09:02 PM - Re: Re: Backup battery - Lightspeed EI (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 01:21:34 AM PST US From: "Greg@itmack" Subject: Re: AeroElectric-List: Soldering question--What am I doing wrong? --> AeroElectric-List message posted by: "Greg@itmack" Sounds like your technique is okay but I think the iron may be a bit small. I like about 60w to keep the heat up when it touches the board. Make sure you're heating both the pad on the board and the LED. You don't need to take the old solder off to re-do a solder joint. Greg Just finished assembling my lights. > --> AeroElectric-List message posted by: Richard Scott > > > I'm building the Creative Air LED nav light kits, working on the LED's. > > So here's what I am doing. > > First I clean up the boards and LED leads with alcohol. > > Put them in the boards & bend the wires. > > Tin the iron. It's a 15 watt iron. > > Put the iron on the connection, then apply the solder. Bill says the > LED's > are heat sensitive and to only hold the iron on them a couple seconds. > > Half the time the solder doesn't penetrate the board, so I only have a > cone > of solder on the lead on one side of the board, the side I am soldering > on. > > To try to fix it, I try to solder it again. > > If that doesn't work (it rarely does), I remove most of the solder using > the iron and a clean cotton swab to absorb the solder & try again. Rarely > works. > > Some of these I try a dozen times & still no joy. > > How can I get a good soldered joint with a cone of solder on both sides of > the board? I have been told that that's what I need for a good > joint. Maybe that guy was wrong? > > Richard Scott > RV-9A > > > ________________________________ Message 2 _____________________________________ Time: 07:03:31 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: Backup battery - Lightspeed EI --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 11:20 PM 3/4/2006 -0500, you wrote: >--> AeroElectric-List message posted by: Ken > >Hi Mark >You sound like you are probably well aware of this but "theoretically" >I'd expect a lot less than 3 hours at 1 amp. >www.power-sonic.com/ps-1229.pdf >These specs indicate that at a 1 amp discharge rate you shouldn't expect >more than 2 hours under ideal conditions or perhaps 1.5 hours for a cold >battery. Apologies for nit-picking. Ken This is not nit-picking. It's considered systems integration with understanding. We've discussed many times here on the List how a battery's useful capacity varies with load. We've also discussed the pitfalls of using the battery's labeled capacity without KNOWING what loads were used to rate that capacity. For example, batteries for bizjets are rated for specific situations where the generators are dead and you're required to power certain systems for 30 minutes. Since battery manufacturers are not regulated to do anything, their ratings may be stated in any lucid manner they choose. Most manufacturers of batteries label their products at a 20 hour discharge rate. Here's a recap of situations we've discussed in the past: In this figure, we can see the published capacity vs. load curves for a popular 33 a.h. battery from Panasonic . . . http://www.aeroelectric.com/Pictures/Curves/LA1233_Panasonic.gif Note that the 33 a.h. rating is met with a 1.65A discharge after 20 hours. Increase the load to 13.2A and you'll get just under two hours of service for a useful capacity of 23.7 a.h. A substantial drop from the label rating. Here are curves produced here in our shop on a single 18 a.h. SVLA battery . . . http://www.aeroelectric.com/Pictures/Curves/1217_3n8_Discharge.pdf Note that due to increased losses in the battery's internal impedance, the useful capacity at 8A is 13.5 a.h. for an operating time of 1.7 hours. Useful capacity at 3 A is 16.8 a.h. for an operating time of 5.6 hours. Finally, here's a discharge curve for battery from Concord for a bizjet with a label capacity of 37 a.h. . . . http://www.aeroelectric.com/Pictures/Curves/Capacity_vs_Voltage.gif Note that it produces 95% of rated capacity when discharged to 22v at 74A . . . this happens in 37/74 hours or 30 minutes. If this battery were re-labeled with a 20 hour rate, the very same battery could be called a 50+ a.h. battery. I'm pleased that you picked up on this Ken, I missed it. Bob . . . >snip > > > used a PowerSonic 2.9 Ah battery (PS-1229). It's light and relatively > cheap (I think about $25-30...you can Google it and get lots of hits). I > plan to change the battery every two years to ensure that it's reasonably > fresh. I know Klaus says 4.5 Ah but I thought that was overkill (unless > you plan to be flying over some really rugged terrain/ocean with no > alternates within an hour or two of flight). The 2.9 Ah batt is > theoretically good for almost 3 hours of run time on one ignition > (drawing ~ 1A at cruise RPM's). In the unlikely event that I ever find > myself operating the engine soley on the backup battery, I will try to > have it on the ground within an hour. > > >snip > > >-- > > Bob . . . < What is so wonderful about scientific truth...is that > < the authority which determines whether there can be > < debate or not does not reside in some fraternity of > < scientists; nor is it divine. The authority rests > < with experiment. > < --Lawrence M. Krauss > ________________________________ Message 3 _____________________________________ Time: 07:29:54 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: My bubble has burst . . . --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" Some of you may recall that I did some studies on energy content of the various alkaline AA cells some time back and found that of all the brands I could lay my hands on at the time, energy content was about the same irrespective of price or advertising hype. I was in Advance Auto Parts last week and they had a 24-pak of Endurance brand alkaline AA cells for $4.88 . . . about 20 cents per cell. The best price in town. I purchased a pack and just for grins, decided to run some on Brutus the Battery Killer. Tests in the past had produced data like: http://www.aeroelectric.com/Pictures/Curves/El-Cheeso_Battery_Test.jpg Two cells tested from my recent purchase look like this: http://www.aeroelectric.com/Pictures/Curves/Endurance_AA.pdf The 20-cent cell is decidedly lower in energy content. However, in terms of cents per milliampere hour, still a reasonable deal since the other bargain products are pushing 37 cents per cell. I'll watch this product and buy another package in 6 months to a year for a retest. The cells I have may have been produced when the chef was having a bad day in the kitchen. Bob . . . < What is so wonderful about scientific truth...is that > < the authority which determines whether there can be > < debate or not does not reside in some fraternity of > < scientists; nor is it divine. The authority rests > < with experiment. > < --Lawrence M. Krauss > ________________________________ Message 4 _____________________________________ Time: 07:41:05 AM PST US Subject: RE: AeroElectric-List: Soldering question--What am I doing wrong? From: "Dan Beadle" --> AeroElectric-List message posted by: "Dan Beadle" Sounds like you could use a little solder flux. . You want electronic flux - not plumbing flux. Digikey sells water soluble flux pens that work great. That makes the heat transfer to the PCB a lot better. You want to heat mostly the PCB trace, especially if it is more massive than the LED lead. Ideally, they both reach flow temperature at the same time. The solder should flow evenly on PCB and lead with a concave shape - not convex or bulbous. If flux doesn't do it, get a larger iron. Radio Shack makes a temperature controlled iron for about $70. Set it to about 600 degrees and you get just the right amount of heat at the junction. Dan -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Greg@itmack Sent: Sunday, March 05, 2006 1:10 AM Subject: Re: AeroElectric-List: Soldering question--What am I doing wrong? --> AeroElectric-List message posted by: "Greg@itmack" Sounds like your technique is okay but I think the iron may be a bit small. I like about 60w to keep the heat up when it touches the board. Make sure you're heating both the pad on the board and the LED. You don't need to take the old solder off to re-do a solder joint. Greg Just finished assembling my lights. > --> AeroElectric-List message posted by: Richard Scott > > > I'm building the Creative Air LED nav light kits, working on the LED's. > > So here's what I am doing. > > First I clean up the boards and LED leads with alcohol. > > Put them in the boards & bend the wires. > > Tin the iron. It's a 15 watt iron. > > Put the iron on the connection, then apply the solder. Bill says the > LED's > are heat sensitive and to only hold the iron on them a couple seconds. > > Half the time the solder doesn't penetrate the board, so I only have a > cone > of solder on the lead on one side of the board, the side I am soldering > on. > > To try to fix it, I try to solder it again. > > If that doesn't work (it rarely does), I remove most of the solder using > the iron and a clean cotton swab to absorb the solder & try again. Rarely > works. > > Some of these I try a dozen times & still no joy. > > How can I get a good soldered joint with a cone of solder on both sides of > the board? I have been told that that's what I need for a good > joint. Maybe that guy was wrong? > > Richard Scott > RV-9A > > > ________________________________ Message 5 _____________________________________ Time: 08:09:18 AM PST US From: "Steve Glasgow" Subject: AeroElectric-List: Attitude Gyro --> AeroElectric-List message posted by: "Steve Glasgow" Artificial Horizon: RCA26AK-4-14V This is an all electric Attitude Gyro that is un-lighted and has an 8 degree panel tilt. It was completely overhauled, by Kelly MFG. CO. 1/10/2006, and is under warranty till 01/10/07. It employs an electrically driven gyro rotor with built-in inverter. Size: 3-3/8"x 7" Wt. 2.7 lbs. Mates with MS3116E8-4S connector. $1,100 or best offer. willfly@carolina.rr.com Steve Glasgow N123SG RV-8 Cappy's Toy 704-362-0005 ________________________________ Message 6 _____________________________________ Time: 09:24:24 AM PST US From: PTACKABURY@aol.com Subject: Re: AeroElectric-List: Re: Composite planes, Metallic paint, and Antennae --> AeroElectric-List message posted by: PTACKABURY@aol.com Bob: Thanks for the second prompt response. After considering your recommendation for an experiment, a logical approach indeed, I am reconsidering my paint choices. Since I have six internal antennas in my Lancair, both in the upper aft fuse and each wing tip and since I would like each to operate as well as possible, I now think using any metallic coatings may be a bad idea. Why introduce even a 20% degradation in performance if it can be avoided? So rather than metallic, I think I will use pearl (plastic additives rather than metallic) to achieve the desired effect. It is a bit more difficult to apply and touch up, but it shouldn't effect nav/com reception--should it? paul ________________________________ Message 7 _____________________________________ Time: 09:57:39 AM PST US From: "J. Mcculley" Subject: Re: AeroElectric-List: Re: Backup battery - Lightspeed EI --> AeroElectric-List message posted by: "J. Mcculley" Bob, Also, I don't want to be a nit-picker but the legend on the graph of your shop discharge test cited below indicates that the black line is a 17AH battery at 3 Amp discharge versus the red line being an 18AH battery at 8 Amp discharge. Is this a typo or am I missing understanding something? I see the 1217,3n8 notation in the web address which I assume means a 12 volt,17AH battery? >Here are curves produced here in our shop on a single 18 a.h. > SVLA battery . . . >http://www.aeroelectric.com/Pictures/Curves/1217_3n8_Discharge.pdf Robert L. Nuckolls, III wrote: > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > At 11:20 PM 3/4/2006 -0500, you wrote: > > >>--> AeroElectric-List message posted by: Ken >> >>Hi Mark >>You sound like you are probably well aware of this but "theoretically" >>I'd expect a lot less than 3 hours at 1 amp > > Bob . . . ________________________________ Message 8 _____________________________________ Time: 10:41:05 AM PST US From: jerb Subject: Re: AeroElectric-List: My bubble has burst . . . --> AeroElectric-List message posted by: jerb Maybe you stumbled upon the reason there cheaper - inconsistent output capacity - produced with lower tolerances, lower acceptance levels (good bin v/s bad reject been), this all affects product cost and shelf price. jerb At 09:26 AM 3/5/2006, you wrote: >--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > >Some of you may recall that I did some studies on >energy content of the various alkaline AA cells some >time back and found that of all the brands I could >lay my hands on at the time, energy content was about >the same irrespective of price or advertising hype. > >I was in Advance Auto Parts last week and they had a 24-pak >of Endurance brand alkaline AA cells for $4.88 . . . about >20 cents per cell. The best price in town. I purchased a >pack and just for grins, decided to run some on Brutus the >Battery Killer. > >Tests in the past had produced data like: > >http://www.aeroelectric.com/Pictures/Curves/El-Cheeso_Battery_Test.jpg > >Two cells tested from my recent purchase look like this: > >http://www.aeroelectric.com/Pictures/Curves/Endurance_AA.pdf > > >The 20-cent cell is decidedly lower in energy content. However, >in terms of cents per milliampere hour, still a reasonable deal >since the other bargain products are pushing 37 cents per cell. > >I'll watch this product and buy another package in 6 months >to a year for a retest. The cells I have may have been produced >when the chef was having a bad day in the kitchen. > > > Bob . . . > > > < What is so wonderful about scientific truth...is that > > < the authority which determines whether there can be > > < debate or not does not reside in some fraternity of > > < scientists; nor is it divine. The authority rests > > < with experiment. > > < --Lawrence M. Krauss > > > ________________________________ Message 9 _____________________________________ Time: 11:10:42 AM PST US From: "Harold" Subject: Re: AeroElectric-List: My bubble has burst . . . --> AeroElectric-List message posted by: "Harold" A real Gem, and a bit of truth ________________________________ Message 10 ____________________________________ Time: 01:15:59 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: My bubble has burst . . . --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 12:35 PM 3/5/2006 -0600, you wrote: >--> AeroElectric-List message posted by: jerb > >Maybe you stumbled upon the reason there cheaper - inconsistent >output capacity - produced with lower tolerances, lower acceptance >levels (good bin v/s bad reject been), this all affects product cost >and shelf price. Sure . . . but within certain boundaries. A blister-pack of 6-32 screws on Walgreen's hardware rack won't be made of recycled pot metal, they won't be 3-18 stainless either. Within narrower confines, theres only so much you can do to a bread recipe before the product is no longer attractive to any customer. And what savings are to be realized by manipulating materials? Many high quality products keep prices low by eliminating no value added activities like TV advertising, too many handlers in the distribution loop, etc. There's rarely much to be gained by short-changing the materials or manufacturing processes. Over the years, we're seeing fewer products that are graded like the old Sears catalogs that offered good, better and best. Semiconductor companies have largely abandoned the military parts business where they simply screened industrial grade parts for more stringent performance limits. The market was tiny and the labor great. Now if we want "mil-spec" parts, we buy a bunch and screen them ourselves. It's interesting that of the parts we do screen, fallout is very low. Usually zero. We could save a lot of money in certificated aircraft if we abandoned our long standing lovefest with anything mil-spec'd. That class of product is approaching extinction because ordinary consumers are demanding equal or BETTER parts than the military wanted . . . and suppliers are building them. So the interesting question to explore was just how much might one diddle with the recipe for an alkaline battery just to have a lower priced niche in on the shelves? I first considered the question in an article for Sport Aviation a few years ago: http://aeroelectric.com/articles/AA_Bat_Test.pdf In that study, I determined that over a wide range of prices, there was little variation in the alkaline batteries to be sampled at the time. I've tested a number of other house brands for folks who sent them to me and found similar results. This new kid on the block seems to be the exception . . . although still a better value than a CopperTop or BunnyBattery purchased at retail. Just a little pothole in the life of those interested in such things . . . I happen to suffer that affliction. Bob . . . ________________________________ Message 11 ____________________________________ Time: 01:15:59 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Backup battery - Lightspeed EI --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 12:53 PM 3/5/2006 -0500, you wrote: >--> AeroElectric-List message posted by: "J. Mcculley" > > >Bob, > >Also, I don't want to be a nit-picker but the legend on the graph of >your shop discharge test cited below indicates that the black line is a >17AH battery at 3 Amp discharge versus the red line being an 18AH >battery at 8 Amp discharge. Is this a typo or am I missing understanding >something? I see the 1217,3n8 notation in the web address which I assume >means a 12 volt,17AH battery? Good catch. I need to fix that. Both graphs were on the same Panasonic LC-RD1217 battery . . . http://www.aeroelectric.com/Reference_Docs/Battery/Panasonic/lc-rd1217p.pdf The 18 a.h. reference is a typo. Bob . . . ________________________________ Message 12 ____________________________________ Time: 01:25:13 PM PST US From: "Robert L. Nuckolls, III" and Antennae Subject: Re: AeroElectric-List: Re: Composite planes, Metallic paint, and Antennae --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" and Antennae At 12:17 PM 3/5/2006 -0500, you wrote: >--> AeroElectric-List message posted by: PTACKABURY@aol.com > >Bob: Thanks for the second prompt response. After considering your >recommendation for an experiment, a logical approach indeed, I >am reconsidering my >paint choices. Since I have six internal antennas in my Lancair, both in >the >upper aft fuse and each wing tip and since I would like each to operate as >well as possible, I now think using any metallic coatings may be a bad >idea. >Why introduce even a 20% degradation in performance if it can be avoided? Whoa . . . I'm not suggesting for a moment that ANY paint you test will produce any noticeable degradation. Odds are that it will produce no effects you can observe. Further, if you DO conduct a test for a particular combination of coatings and find that it has no observable effect (or perhaps only barely twitches the readings) . . . that's GOOD data to share with others. >So rather than metallic, I think I will use pearl (plastic additives >rather than >metallic) to achieve the desired effect. It is a bit more difficult to >apply and touch up, but it shouldn't effect nav/com reception--should >it? paul Probably won't . . . but there's no calibration on "probably". So much of what passes for good advice is based on subjective observations. A builder who reports great antenna performance and never talks to stations more than 10 miles away might get similar results with a wet string. On the other hand, a builder who is disappointed that he can't hit an RCO out on the horizon of some leg of a favorite trip might have an entirely different opinion on the same antenna. There's nothing like numbers from the repeatable experiment to add real value to one's advice. Even if backyard experimenting is not your bag . . . risks for using the paint you described are very low. Bob . . . < What is so wonderful about scientific truth...is that > < the authority which determines whether there can be > < debate or not does not reside in some fraternity of > < scientists; nor is it divine. The authority rests > < with experiment. > < --Lawrence M. Krauss > ________________________________ Message 13 ____________________________________ Time: 02:05:51 PM PST US From: Brian Lloyd Subject: Re: AeroElectric-List: Re: Backup battery - Lightspeed EI --> AeroElectric-List message posted by: Brian Lloyd J. Mcculley wrote: > --> AeroElectric-List message posted by: "J. Mcculley" > > Bob, > > Also, I don't want to be a nit-picker but the legend on the graph of > your shop discharge test cited below indicates that the black line is a > 17AH battery at 3 Amp discharge versus the red line being an 18AH > battery at 8 Amp discharge. Is this a typo or am I missing understanding > something? I see the 1217,3n8 notation in the web address which I assume > means a 12 volt,17AH battery? The curves look correct to me. They are a bit odd in that normally one plots voltage against time for a given discharge rate (constant current) but you can always divide the amp-hour scale by amps to get the hours. what might be more interesting would be to plot the endpoints (11V or 10.5V, whatever you select for "dead") and the amp-hours delivered for each discharge rate. That would show you how much energy is available from your battery at different discharge rates. You could also calculate Peukert's exponent for your battery so you can figure out its remaining capacity even at varying discharge rates. -- Brian Lloyd 361 Catterline Way brian-yak at lloyd dot com Folsom, CA 95630 +1.916.367.2131 (voice) +1.270.912.0788 (fax) I fly because it releases my mind from the tyranny of petty things . . . - Antoine de Saint-Exupery ________________________________ Message 14 ____________________________________ Time: 02:07:28 PM PST US From: Brian Lloyd Subject: Re: AeroElectric-List: Re: Backup battery - Lightspeed EI --> AeroElectric-List message posted by: Brian Lloyd Robert L. Nuckolls, III wrote: >> battery at 8 Amp discharge. Is this a typo or am I missing understanding >> something? I see the 1217,3n8 notation in the web address which I assume >> means a 12 volt,17AH battery? > > Good catch. I need to fix that. Both graphs were on the same > Panasonic LC-RD1217 battery . . . > > http://www.aeroelectric.com/Reference_Docs/Battery/Panasonic/lc-rd1217p.pdf > > The 18 a.h. reference is a typo. Is this a gelled electrolyte battery or an AGM battery? My guess from looking at the voltage sag is that it is a gel-cell. -- Brian Lloyd 361 Catterline Way brian-yak at lloyd dot com Folsom, CA 95630 +1.916.367.2131 (voice) +1.270.912.0788 (fax) I fly because it releases my mind from the tyranny of petty things . . . - Antoine de Saint-Exupery ________________________________ Message 15 ____________________________________ Time: 02:59:50 PM PST US From: "Brinker" Subject: AeroElectric-List: Heated Pitot test --> AeroElectric-List message posted by: "Brinker" I bought a used 12v heated pitot removed from a Piper Seminole off of ebay claimed to be servicable and tested. I have never hooked up one of these. It has two terminals to hook up wires. But accually has 2 wires now soldered to one terminal and one wire soldered to the second terminal but appears a second wire was at one time soldered to the second terminal. The only verifiable markings are a "p" and an "s" I believe designate which tube is the pitot and static ports. But no marking for positive or negitive. I will not be installing this for a while since I have a ways to go on building my plane but wish to at least test it before storing it for later. Randy ________________________________ Message 16 ____________________________________ Time: 03:28:46 PM PST US From: Brian Lloyd Subject: Re: AeroElectric-List: Heated Pitot test --> AeroElectric-List message posted by: Brian Lloyd Brinker wrote: > --> AeroElectric-List message posted by: "Brinker" > > I bought a used 12v heated pitot removed from a Piper Seminole off > of ebay claimed to be servicable and tested. I have never hooked up one of > these. It has two terminals to hook up wires. But accually has 2 wires now > soldered to one terminal and one wire soldered to the second terminal but > appears a second wire was at one time soldered to the second terminal. > The only verifiable markings are a "p" and an "s" I believe designate > which tube is the pitot and static ports. But no marking for positive or > negitive. > I will not be installing this for a while since I have a ways to go > on building my plane but wish to at least test it before storing it for > later. Since the heating element is a resistor, there is no polarity. If it was designed to work on either 12V or 24V there will be two elements. Use them in series for 24V and in parallel for 12V. And the latter is just a guess on my part. -- Brian Lloyd 361 Catterline Way brian-yak at lloyd dot com Folsom, CA 95630 +1.916.367.2131 (voice) +1.270.912.0788 (fax) I fly because it releases my mind from the tyranny of petty things . . . - Antoine de Saint-Exupery ________________________________ Message 17 ____________________________________ Time: 03:52:14 PM PST US From: "Dennis Johnson" Subject: AeroElectric-List: Zener Diodes and LEDs --> AeroElectric-List message posted by: "Dennis Johnson" I'm making LED instrument floodlights and LED lights for an annunciator panel. I expect the system voltage to vary between about 13.8 volts when the engine and alternator are running, down to about 12.4 volts running just off a lightly loaded battery. When connecting the LEDs in a series string of three, the resistance required to get the voltage to the recommended level for the LEDs at the 13.8 system voltage is different than when the system voltage is 12.4. Although it doesn't make a huge difference in the amount of light that comes out of the LEDs, it is noticeable. I'm wondering (which often gets me into trouble) if I couldn't use zener diodes instead of resistors to solve the problem of the light output varying with system voltage. For example, if I have an array of three LEDs, each with a Vf of 1.7 volts, could I use a 5.1 volt zener diode instead of resistors? I don't have any experience with zener diodes, but the catalogs make it sound like they produce a stable voltage output when operated within their amperage limitations, sort of like a cheap power supply. Digikey sells them for only a little more than resistors, so cost isn't an issue. Admittedly, the varying light output isn't a huge problem, but if it's just as easy and cheap to use zeners, why use resistors? Thanks, Dennis Johnson Lancair Legacy #257, wiring in (slow) progress ________________________________ Message 18 ____________________________________ Time: 04:30:49 PM PST US From: Brian Lloyd Subject: Re: AeroElectric-List: Zener Diodes and LEDs --> AeroElectric-List message posted by: Brian Lloyd Dennis Johnson wrote: > I'm wondering (which often gets me into trouble) if I couldn't use zener diodes instead of resistors to solve the problem of the light output varying with system voltage. For example, if I have an array of three LEDs, each with a Vf of 1.7 volts, could I use a 5.1 volt zener diode instead of resistors? Actually, that would make the problem worse. You would get a huge change in light output with only a tiny change in voltage. Light output from an LED is a function of the current through it and the current through an LED is not linear with applied voltage. The resistor acts as a ballast to make the current change more linear with voltage so that a 0.3V change doesn't cause the LED to go from no output to full output. What you really want to make is a constant current source. This would make the light output independent of bus voltage. Another way to stabilize light output is to regulate your bus voltage down to something like 9V, using that to power your LEDs. -- Brian Lloyd 361 Catterline Way brian-yak at lloyd dot com Folsom, CA 95630 +1.916.367.2131 (voice) +1.270.912.0788 (fax) I fly because it releases my mind from the tyranny of petty things . . . - Antoine de Saint-Exupery ________________________________ Message 19 ____________________________________ Time: 05:19:39 PM PST US Subject: RE: AeroElectric-List: Zener Diodes and LEDs From: "Dan Beadle" --> AeroElectric-List message posted by: "Dan Beadle" You can use a resistor and Zener diode to make a constant voltage source for the LEDs as you say. This is not terribly efficient, but easy to assemble. You don't say what the current is that you need. Let's assume that it is 100mA (.1A). If the system voltage is at 13.8V and you want to use just fixed resistors, the voltage drop through the resistor would be 13.8-5.1 (target) or 8.7V. The R required would be Vd/I = R or 8.7/.1 R = 87 ohms... So far, so good. But if the voltage in drops a bit, the same current still gets dropped 8.7V by the R... causing the LEDs to dim a little. You can get a constant 5.1V at the LEDs with a 5.1V Zener. Pick the current you want and the lowest voltage you want. Let's stay with the .1A and set the lower drop out at 10.1V for a Vd of 5V. To get a current of .1A, you would need R to be 50 ohms. But at 13.8V, the drop would not be enough. Zener to the rescue: | -> LED1 -> LED2 -LED3 | Hook up as Vin (14v) -> R ->| | -> gnd | -> Zener(Band-Cathode)---Zener Anode | When the voltage goes above 10.1V, the Zener will conduct enough to cause additional voltage drop through the R, holding the voltage at 5.1V to the LEDs... Finally, you have to look at the wattage for both the R and the Zener. Continuing the example, the max drop across the R would be something like 14.5-5.1 or 9.4V. Watts = V*V/R = 9.4v * 9.4 / 50 , so 1 Watt would work in this example For the Zener, the voltage drop is 5.1V, the current is the current through the R (V/R or 9.4/50 = 188mA), less any current diverted to the LEDs. Assuming they draw .1A, the current through the Zener would be 188-100, or 88mA. So the wattage would be V*I or 9.4*0.088 = .88W. So use a 1W or larger Zener. Hope this helps. Dan -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Brian Lloyd Sent: Sunday, March 05, 2006 4:25 PM Subject: Re: AeroElectric-List: Zener Diodes and LEDs --> AeroElectric-List message posted by: Brian Lloyd Dennis Johnson wrote: > I'm wondering (which often gets me into trouble) if I couldn't use zener diodes instead of resistors to solve the problem of the light output varying with system voltage. For example, if I have an array of three LEDs, each with a Vf of 1.7 volts, could I use a 5.1 volt zener diode instead of resistors? Actually, that would make the problem worse. You would get a huge change in light output with only a tiny change in voltage. Light output from an LED is a function of the current through it and the current through an LED is not linear with applied voltage. The resistor acts as a ballast to make the current change more linear with voltage so that a 0.3V change doesn't cause the LED to go from no output to full output. What you really want to make is a constant current source. This would make the light output independent of bus voltage. Another way to stabilize light output is to regulate your bus voltage down to something like 9V, using that to power your LEDs. -- Brian Lloyd 361 Catterline Way brian-yak at lloyd dot com Folsom, CA 95630 +1.916.367.2131 (voice) +1.270.912.0788 (fax) I fly because it releases my mind from the tyranny of petty things . . . - Antoine de Saint-Exupery ________________________________ Message 20 ____________________________________ Time: 05:27:58 PM PST US From: "Richard E. Tasker" Subject: Re: AeroElectric-List: Zener Diodes and LEDs --> AeroElectric-List message posted by: "Richard E. Tasker" Short answer.. No. Longer answer below... Resistors limit the current through the LEDs to whatever you want (20 mA maybe). More source voltage just means a little more current and a little brighter LED. The extra voltage is dropped across the resistor, not the LEDs. LEDs actually have a voltage current characteristic similar to zeners which limit the voltage across themselves. If you string the LEDs and a zener together, they will not emit any light until the voltage reaches whatever minimum is required across the LEDs and the zener - 10.2 volts in your case - and then burn out as the voltage tries to go higher.. If what you are suggesting is to place a 5.1V zener in parallel with the LEDs and a resistor in series with the zener and LEDs, that will sorta work as long as you don't mind wasting some extra power. Since LEDs have slightly different voltage drops and since this changes somewhat with temperature and since the same happens with a zener, using a simple circuit like you are suggesting won't really work. You would have to use a zener nd two resistors to make something that would work and you would be throwing away a significant amount of power, since what you would be doing is constructing a simple shunt regulator. Basically you would use the zener and a resistor to create a shunt regulated voltage source and then string the LEDs and an additional resistor across the zener. A better way to accomplish what you want to do would be to use a three terminal regulator such as the LM317 and hook it up as a current sink in series with the LEDs. This requires nothing more than a single resistor and the LM317 and what happens is that the regulator operates to keep the same current through the LEDs regardless what the external power does - keeping the LEDs the same brightness as the voltage varies from 12.4 (or less) to 13.8. You can hook the power source to the regulator and then the regulator to the LEDs and then to ground or you can hook the power source to the LEDs and then to the regulator and then to ground - make no difference as long as they are connected in series. Download the datasheet from: http://www.national.com/pf/LM/LM317L.html (about 1/4 down the page) and then look at the bottom of page 17 of the datasheet for a current regulator. You do not need the pot, just a fixed resistor works fine calculated per the accompanying formula (Vref is 1.25V). So to get 20 mA you would use I=1.25/R, or R = 1.25/.02 or 62.5 ohms (or the closest standard resistor value). The part is available from Digikey or Mouser or any number of other electronics supply houses. Or you can just use a resistor and live with the slight change in brightness. Any questions, ask :-) . Dick Tasker Dennis Johnson wrote: >--> AeroElectric-List message posted by: "Dennis Johnson" > >I'm making LED instrument floodlights and LED lights for an annunciator panel. I expect the system voltage to vary between about 13.8 volts when the engine and alternator are running, down to about 12.4 volts running just off a lightly loaded battery. > >When connecting the LEDs in a series string of three, the resistance required to get the voltage to the recommended level for the LEDs at the 13.8 system voltage is different than when the system voltage is 12.4. Although it doesn't make a huge difference in the amount of light that comes out of the LEDs, it is noticeable. > >I'm wondering (which often gets me into trouble) if I couldn't use zener diodes instead of resistors to solve the problem of the light output varying with system voltage. For example, if I have an array of three LEDs, each with a Vf of 1.7 volts, could I use a 5.1 volt zener diode instead of resistors? > >I don't have any experience with zener diodes, but the catalogs make it sound like they produce a stable voltage output when operated within their amperage limitations, sort of like a cheap power supply. Digikey sells them for only a little more than resistors, so cost isn't an issue. Admittedly, the varying light output isn't a huge problem, but if it's just as easy and cheap to use zeners, why use resistors? > >Thanks, >Dennis Johnson >Lancair Legacy #257, wiring in (slow) progress > > > > > > > > > -- Please Note: No trees were destroyed in the sending of this message. We do concede, however, that a significant number of electrons may have been temporarily inconvenienced. -- ________________________________ Message 21 ____________________________________ Time: 05:53:31 PM PST US Subject: RE: AeroElectric-List: Zener Diodes and LEDs From: "Dan Beadle" --> AeroElectric-List message posted by: "Dan Beadle" Better solution than mine. As you point out, the LEDs need constant current, not constant voltage. Selecting a the zener higher voltage, with current limiting behind it to the LEDs would work fine. But, with less efficiency than a current regulator configuration. -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Richard E. Tasker Sent: Sunday, March 05, 2006 5:25 PM Subject: Re: AeroElectric-List: Zener Diodes and LEDs --> AeroElectric-List message posted by: "Richard E. Tasker" Short answer.. No. Longer answer below... Resistors limit the current through the LEDs to whatever you want (20 mA maybe). More source voltage just means a little more current and a little brighter LED. The extra voltage is dropped across the resistor, not the LEDs. LEDs actually have a voltage current characteristic similar to zeners which limit the voltage across themselves. If you string the LEDs and a zener together, they will not emit any light until the voltage reaches whatever minimum is required across the LEDs and the zener - 10.2 volts in your case - and then burn out as the voltage tries to go higher.. If what you are suggesting is to place a 5.1V zener in parallel with the LEDs and a resistor in series with the zener and LEDs, that will sorta work as long as you don't mind wasting some extra power. Since LEDs have slightly different voltage drops and since this changes somewhat with temperature and since the same happens with a zener, using a simple circuit like you are suggesting won't really work. You would have to use a zener nd two resistors to make something that would work and you would be throwing away a significant amount of power, since what you would be doing is constructing a simple shunt regulator. Basically you would use the zener and a resistor to create a shunt regulated voltage source and then string the LEDs and an additional resistor across the zener. A better way to accomplish what you want to do would be to use a three terminal regulator such as the LM317 and hook it up as a current sink in series with the LEDs. This requires nothing more than a single resistor and the LM317 and what happens is that the regulator operates to keep the same current through the LEDs regardless what the external power does - keeping the LEDs the same brightness as the voltage varies from 12.4 (or less) to 13.8. You can hook the power source to the regulator and then the regulator to the LEDs and then to ground or you can hook the power source to the LEDs and then to the regulator and then to ground - make no difference as long as they are connected in series. Download the datasheet from: http://www.national.com/pf/LM/LM317L.html (about 1/4 down the page) and then look at the bottom of page 17 of the datasheet for a current regulator. You do not need the pot, just a fixed resistor works fine calculated per the accompanying formula (Vref is 1.25V). So to get 20 mA you would use I=1.25/R, or R = 1.25/.02 or 62.5 ohms (or the closest standard resistor value). The part is available from Digikey or Mouser or any number of other electronics supply houses. Or you can just use a resistor and live with the slight change in brightness. Any questions, ask :-) . Dick Tasker Dennis Johnson wrote: >--> AeroElectric-List message posted by: "Dennis Johnson" > >I'm making LED instrument floodlights and LED lights for an annunciator panel. I expect the system voltage to vary between about 13.8 volts when the engine and alternator are running, down to about 12.4 volts running just off a lightly loaded battery. > >When connecting the LEDs in a series string of three, the resistance required to get the voltage to the recommended level for the LEDs at the 13.8 system voltage is different than when the system voltage is 12.4. Although it doesn't make a huge difference in the amount of light that comes out of the LEDs, it is noticeable. > >I'm wondering (which often gets me into trouble) if I couldn't use zener diodes instead of resistors to solve the problem of the light output varying with system voltage. For example, if I have an array of three LEDs, each with a Vf of 1.7 volts, could I use a 5.1 volt zener diode instead of resistors? > >I don't have any experience with zener diodes, but the catalogs make it sound like they produce a stable voltage output when operated within their amperage limitations, sort of like a cheap power supply. Digikey sells them for only a little more than resistors, so cost isn't an issue. Admittedly, the varying light output isn't a huge problem, but if it's just as easy and cheap to use zeners, why use resistors? > >Thanks, >Dennis Johnson >Lancair Legacy #257, wiring in (slow) progress > > > > > > > > > -- Please Note: No trees were destroyed in the sending of this message. We do concede, however, that a significant number of electrons may have been temporarily inconvenienced. -- ________________________________ Message 22 ____________________________________ Time: 06:34:11 PM PST US From: "Dennis Johnson" Subject: AeroElectric-List: Followup to Zener/LED Question --> AeroElectric-List message posted by: "Dennis Johnson" I've already received a few excellent responses to my question about using zener diodes to regulate power to an LED light. Thanks so much for your very thoughtful answers. It's obvious that my understanding of LEDs is flawed. I have a couple of basic questions to get me back on track and that will allow me to fully understand your replies: Assume an LED with a Vf of 2.1 volts and 20 mA rating: 1. If I hook the LED to a power supply fixed at 2.1 volts but with an unlimited capacity to supply current, what would happen to the LED? 2. If I hook up the LED to a power supply set to 48 volts or so but with the current limited to 20 mA, what would happen to the LED? I have a handful of miscellaneous LEDs and I'd try the experiment myself if I had a power supply. It's a great day when I can learn something new, particularly if it's useful! Thanks, Dennis Johnson Lancair Legacy --- currently revising my instrument panel LED lighting plan ________________________________ Message 23 ____________________________________ Time: 06:56:36 PM PST US Subject: RE: AeroElectric-List: Followup to Zener/LED Question From: "Dan Beadle" --> AeroElectric-List message posted by: "Dan Beadle" Basically, you want a current limiter in the circuit. That is what the resistor does. So your 48V/20ma example probably work (depending upon the current spec of the LED). But if you hook to 2.1V supply, you may get no output if the Vf is > 2.1V (high tolerance) or high current, light, and maybe the magic smoke, if the Vf is < 2.1V -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Dennis Johnson Sent: Sunday, March 05, 2006 6:31 PM Subject: AeroElectric-List: Followup to Zener/LED Question --> AeroElectric-List message posted by: "Dennis Johnson" I've already received a few excellent responses to my question about using zener diodes to regulate power to an LED light. Thanks so much for your very thoughtful answers. It's obvious that my understanding of LEDs is flawed. I have a couple of basic questions to get me back on track and that will allow me to fully understand your replies: Assume an LED with a Vf of 2.1 volts and 20 mA rating: 1. If I hook the LED to a power supply fixed at 2.1 volts but with an unlimited capacity to supply current, what would happen to the LED? 2. If I hook up the LED to a power supply set to 48 volts or so but with the current limited to 20 mA, what would happen to the LED? I have a handful of miscellaneous LEDs and I'd try the experiment myself if I had a power supply. It's a great day when I can learn something new, particularly if it's useful! Thanks, Dennis Johnson Lancair Legacy --- currently revising my instrument panel LED lighting plan ________________________________ Message 24 ____________________________________ Time: 07:29:23 PM PST US From: "Richard E. Tasker" Subject: Re: AeroElectric-List: Followup to Zener/LED Question --> AeroElectric-List message posted by: "Richard E. Tasker" Dennis Johnson wrote: >--> AeroElectric-List message posted by: "Dennis Johnson" > >I've already received a few excellent responses to my question about using zener diodes to regulate power to an LED light. Thanks so much for your very thoughtful answers. It's obvious that my understanding of LEDs is flawed. I have a couple of basic questions to get me back on track and that will allow me to fully understand your replies: > >Assume an LED with a Vf of 2.1 volts and 20 mA rating: > >1. If I hook the LED to a power supply fixed at 2.1 volts but with an unlimited capacity to supply current, what would happen to the LED? > > Well, it depends on whether the power supply is exactly the 2.1 volts of the zener Vf. If it is exactly the 2.1 volts then the zener will light up with the 20 mA brightness. If it is a little higher (2.2V) it will light up much brighter since it will draw much more current. A little higher still and - Toast! If you plot voltage on the X axis and current on the Y axis, a resistor would be a straight line pointing up and to the right. A zener would be "L" shaped with a little bit of rounding at the apex of the "L"- very little current until it reaches the zener voltage and then the current would rise very fast for just a little more voltage. An LED is similar except the apex is a little more rounded than the zener. Zeners and LEDs MUST have something to limit the current or they will overheat and die when the voltage rises a little above the Vf or zener voltage. >2. If I hook up the LED to a power supply set to 48 volts or so but with the current limited to 20 mA, what would happen to the LED? > > It would light to whatever brightness that 20 mA creates. If you use a resistor, the brightness would change if you varied the 48 volts. If you used an active current limiter such as I described earlier, the brightness would stay constant. If you plotted the active limiter as above, you would get a straight horizontal line from about 3V to 38V (the maximum voltage limit of the LM317). Below 3V or so you would get essentially no current. The only drawback to the active current limiter is that it doesn't allow the LED to change brightness if you wanted to dim it with a normal dimmer. You have to use one of the digital dimmers (pulse width controlled) to dim it. >I have a handful of miscellaneous LEDs and I'd try the experiment myself if I had a power supply. > >It's a great day when I can learn something new, particularly if it's useful! > >Thanks, >Dennis Johnson >Lancair Legacy --- currently revising my instrument panel LED lighting plan > -- Please Note: No trees were destroyed in the sending of this message. We do concede, however, that a significant number of electrons may have been temporarily inconvenienced. -- ________________________________ Message 25 ____________________________________ Time: 07:38:42 PM PST US From: "Richard E. Tasker" Subject: Re: AeroElectric-List: Followup to Zener/LED Question --> AeroElectric-List message posted by: "Richard E. Tasker" Ooops! Actually, in my previous post it would be a backwards "L" shape. Dennis Johnson wrote: >--> AeroElectric-List message posted by: "Dennis Johnson" > >I've already received a few excellent responses to my question about using zener diodes to regulate power to an LED light. Thanks so much for your very thoughtful answers. It's obvious that my understanding of LEDs is flawed. I have a couple of basic questions to get me back on track and that will allow me to fully understand your replies: > >Assume an LED with a Vf of 2.1 volts and 20 mA rating: > >1. If I hook the LED to a power supply fixed at 2.1 volts but with an unlimited capacity to supply current, what would happen to the LED? > >2. If I hook up the LED to a power supply set to 48 volts or so but with the current limited to 20 mA, what would happen to the LED? > >I have a handful of miscellaneous LEDs and I'd try the experiment myself if I had a power supply. > >It's a great day when I can learn something new, particularly if it's useful! > >Thanks, >Dennis Johnson >Lancair Legacy --- currently revising my instrument panel LED lighting plan > -- Please Note: No trees were destroyed in the sending of this message. We do concede, however, that a significant number of electrons may have been temporarily inconvenienced. -- ________________________________ Message 26 ____________________________________ Time: 08:02:27 PM PST US From: Charlie Kuss Subject: Re: AeroElectric-List: Heated Pitot test --> AeroElectric-List message posted by: Charlie Kuss Randy, There are two heating elements in the Piper style heated pitot tube. One is a 70 watt unit, the other is 100 watts. I've seen the wires of both heating elements crimped together before. Cut the wires apart, so that you can insure that BOTH elements work. Check for continuity between both wires of each element. I believe my pitot elements ohm out at about 3 ohms. An infinite reading will be that the element being tested is bad. Connect each elements 2 wires to a 12 volt battery (check one element at a time) using 16 or 14 AWG wire. The Pitot should start to warm up in your hand within 30 to 60 seconds. Do not apply power for a period of time longer than is needed to verify that each element works. If you have a bad element, they can be replaced. A number of outfits will charge you a hefty price for these parts. RV-9A builder Peter Laurence tracked down the "source" for these units. They are available for a reasonable price from HotWatt. See Peter's email to me below for more info. Charlie Kuss Charlie, Here is the info. Heaters are made by Hotwatt Http://www.hotwatt.com/cartridg.htm Hotwatt part #s For Pitot: 13A7025 70 W 12V Static 13A7026 100W 14V Piper part #s 464-356 for the 70W 12V 464-357 for the 100W 14V These are called cartridge heaters. They are 3"X 3/16" and 4"X 3/16" Check the ceramic plug where the wire enters the cartridge. If there's any movement of the wire, it should be replaced. Peter Laurence >--> AeroElectric-List message posted by: "Brinker" > > I bought a used 12v heated pitot removed from a Piper Seminole off >of ebay claimed to be servicable and tested. I have never hooked up one of >these. It has two terminals to hook up wires. But accually has 2 wires now >soldered to one terminal and one wire soldered to the second terminal but >appears a second wire was at one time soldered to the second terminal. > The only verifiable markings are a "p" and an "s" I believe designate >which tube is the pitot and static ports. But no marking for positive or >negitive. > I will not be installing this for a while since I have a ways to go >on building my plane but wish to at least test it before storing it for >later. > >Randy > > ________________________________ Message 27 ____________________________________ Time: 08:02:27 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Backup battery - Lightspeed EI --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 02:06 PM 3/5/2006 -0800, you wrote: >--> AeroElectric-List message posted by: Brian Lloyd > >Robert L. Nuckolls, III wrote: > > >> battery at 8 Amp discharge. Is this a typo or am I missing understanding > >> something? I see the 1217,3n8 notation in the web address which I assume > >> means a 12 volt,17AH battery? > > > > Good catch. I need to fix that. Both graphs were on the same > > Panasonic LC-RD1217 battery . . . > > > > http://www.aeroelectric.com/Reference_Docs/Battery/Panasonic/lc-rd1217p.pdf > > > > The 18 a.h. reference is a typo. > >Is this a gelled electrolyte battery or an AGM battery? My guess from >looking at the voltage sag is that it is a gel-cell. Gel cells are almost non-existent in the wild. If you have a real gel-cell it will probably say so in the literature and even on the side of the battery. Gels are a modified flooded battery where enough jello like stuff was added to make the normally liquid stuff stay in place when the battery was inverted. Globe Union were biggies in Gels about 25 years ago, Sonnenschein makes them in Europe. The first spill proof battery B&C sold was the Gates energy jelly-roll cells which were a true AGM, SVLA, RG, Immmobilized Electrolyte, starved electrolyte battery . . . but not a gel-cell. When the Gates product proved unworthy of flight in aircraft, B&C switched to the Sonnenschein gels for a time but those were replaced by the Genesis series (all the above types) and ultimately STD'd onto a bunch of airplanes. Gel-cells are popular for deep cycle applications like electric wheelchairs. They seem to perform better than their dryer cousins. I think B&C still has one gel-cell offering. Some folks like Delmar Benjamin swear by them and he Bill aims to please. The vast majority of lead-acid products are of the SVLA/RG variety and you have to go out of your way to find a gel-cell. Unfortunately, most of the storefronts who stock these modern marvels refer to them as gel-cells and help perpetuate a huge mis-information. Bob . . . < What is so wonderful about scientific truth...is that > < the authority which determines whether there can be > < debate or not does not reside in some fraternity of > < scientists; nor is it divine. The authority rests > < with experiment. > < --Lawrence M. Krauss > ________________________________ Message 28 ____________________________________ Time: 08:42:53 PM PST US From: "Malcolm Thomson" Subject: RE: AeroElectric-List: Zener Diodes and LEDs --> AeroElectric-List message posted by: "Malcolm Thomson" Looks like this is what you need. See http://www.periheliondesign.com/Vregflyer.htm Malcolm. -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Dennis Johnson Sent: Sunday, March 05, 2006 4:49 PM Subject: AeroElectric-List: Zener Diodes and LEDs --> AeroElectric-List message posted by: "Dennis Johnson" --> I'm making LED instrument floodlights and LED lights for an annunciator panel. I expect the system voltage to vary between about 13.8 volts when the engine and alternator are running, down to about 12.4 volts running just off a lightly loaded battery. When connecting the LEDs in a series string of three, the resistance required to get the voltage to the recommended level for the LEDs at the 13.8 system voltage is different than when the system voltage is 12.4. Although it doesn't make a huge difference in the amount of light that comes out of the LEDs, it is noticeable. I'm wondering (which often gets me into trouble) if I couldn't use zener diodes instead of resistors to solve the problem of the light output varying with system voltage. For example, if I have an array of three LEDs, each with a Vf of 1.7 volts, could I use a 5.1 volt zener diode instead of resistors? I don't have any experience with zener diodes, but the catalogs make it sound like they produce a stable voltage output when operated within their amperage limitations, sort of like a cheap power supply. Digikey sells them for only a little more than resistors, so cost isn't an issue. Admittedly, the varying light output isn't a huge problem, but if it's just as easy and cheap to use zeners, why use resistors? Thanks, Dennis Johnson Lancair Legacy #257, wiring in (slow) progress -- -- ________________________________ Message 29 ____________________________________ Time: 08:45:42 PM PST US From: Brian Lloyd Subject: Re: AeroElectric-List: Re: Backup battery - Lightspeed EI --> AeroElectric-List message posted by: Brian Lloyd Robert L. Nuckolls, III wrote: > Gel cells are almost non-existent in the wild. If you have a real > gel-cell it will probably say so in the literature and even on the > side of the battery. Gels are a modified flooded battery where > enough jello like stuff was added to make the normally liquid > stuff stay in place when the battery was inverted. Gel-cells are rather common in the boating community. They are clearly delineated as such. > Globe Union were biggies in Gels about 25 years ago, Sonnenschein > makes them in Europe. The first spill proof battery B&C sold was > the Gates energy jelly-roll cells which were a true AGM, SVLA, > RG, Immmobilized Electrolyte, starved electrolyte battery . . . but > not a gel-cell. When the Gates product proved unworthy of flight > in aircraft, B&C switched to the Sonnenschein gels for a time but > those were replaced by the Genesis series (all the above types) > and ultimately STD'd onto a bunch of airplanes. No argument there. > Gel-cells are popular for deep cycle applications like electric > wheelchairs. They seem to perform better than their dryer > cousins. I think B&C still has one gel-cell offering. Some folks > like Delmar Benjamin swear by them and he Bill aims to please. I happen to like gels myself as their acceptable absorption charge voltage range overlaps with the acceptable float charge voltage range. You can get away with a single-voltage charging system (like an aircraft's alternator). Also, gels seem to tolerate extended partial discharge better than AGMs. This makes them more attractive in power systems where the battery does not get completely recharged every time. But their higher internal resistance makes them poor starting batteries unless they are oversized for the task. > The vast majority of lead-acid products are of the SVLA/RG Gel-cells are RG (recombinant gas) batteries also. I am not familiar with the term SVLA tho. RG - recombinant gas VRLA - valve-regulated lead-acid AGM - absorbed glass-mat GELA - gelled-electrolyte lead-acid BTW, VRLA or RG can refer to *either* GELA or AGM batteries. I am attaching a really good treatise on VRLA batteries from Deka-Penn. Clearly they are trying to sell their own product and it is a bit simplistic in some areas but their stuff on charging and discharging is really good. The best thing about it is that it addresses the differences in operation of GELA and AGM batteries. > variety and you have to go out of your way to find a gel-cell. I disagree. I have no trouble finding gel-cells and use them where I think they will perform better. They have higher internal resistance than do AGMs but they are less prone to failure on overcharge than are AGMs. They also tolerate partial or complete discharge better than AGMs. > Unfortunately, most of the storefronts who stock these modern > marvels refer to them as gel-cells and help perpetuate a huge > mis-information. Bob, I know the difference. I read the manufacturer's literature so I know what I am buying. I don't trust what stores tell me because, frankly, I usually know more about the topic than does the store. GELA batteries are common enough that I would not pretend to know what is inside the case unless the lit clearly states one way or another. -- Brian Lloyd 361 Catterline Way brian-yak at lloyd dot com Folsom, CA 95630 +1.916.367.2131 (voice) +1.270.912.0788 (fax) I fly because it releases my mind from the tyranny of petty things . . . - Antoine de Saint-Exupery ________________________________ Message 30 ____________________________________ Time: 09:02:57 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Backup battery - Lightspeed EI --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 02:01 PM 3/5/2006 -0800, you wrote: >--> AeroElectric-List message posted by: Brian Lloyd > > >J. Mcculley wrote: > > --> AeroElectric-List message posted by: "J. Mcculley" > > > > > Bob, > > > > Also, I don't want to be a nit-picker but the legend on the graph of > > your shop discharge test cited below indicates that the black line is a > > 17AH battery at 3 Amp discharge versus the red line being an 18AH > > battery at 8 Amp discharge. Is this a typo or am I missing understanding > > something? I see the 1217,3n8 notation in the web address which I assume > > means a 12 volt,17AH battery? > >The curves look correct to me. They are a bit odd in that normally one >plots voltage against time for a given discharge rate (constant current) >but you can always divide the amp-hour scale by amps to get the hours. > >what might be more interesting would be to plot the endpoints (11V or >10.5V, whatever you select for "dead") and the amp-hours delivered for >each discharge rate. That would show you how much energy is available >from your battery at different discharge rates. You could also calculate >Peukert's exponent for your battery so you can figure out its remaining >capacity even at varying discharge rates. Yeah . . . I've had some conversation with the folks at WestMountainRadio about this. Obviously, the ampere-hour is NOT a measure of energy. When I purchased my first battery tester from them, I suggested some enhancements for the next release of their software. We engineers would really like to see constant wattage and constant resistance discharge functions in addition to the standard constant current function. Then too, as you've noted, a volts vs. time and energy vs. time plots would be more meaningful along with an box on the graph that displayed watt-seconds of energy at the endpoint. He seemed receptive. I'll write again and see where that might set on his stove's burners. I'd REALLY like to recommend his tool to others in the battery business but most would like some features besides the arcane and poorly-descriptive ampere-hour display. He's 100% of the way there with hardware, what he needs now is a really cool GUI. Bob . . .