---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 06/08/07: 20 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:36 AM - Re: Runaway trim (Greg Campbell) 2. 06:33 AM - Re: Runaway trim () 3. 07:41 AM - Re: Annunciator HELP! (Robert L. Nuckolls, III) 4. 07:49 AM - Re: Annunciator HELP! (Robert L. Nuckolls, III) 5. 09:54 AM - Re: Annunciator HELP! (Richard Tasker) 6. 10:07 AM - Re: Annunciator HELP! (john@ballofshame.com) 7. 11:28 AM - Re: Annunciator HELP! (Ron Quillin) 8. 12:12 PM - Re: Annunciator HELP! (Robert L. Nuckolls, III) 9. 12:40 PM - Re: Annunciator HELP! (Fiveonepw@aol.com) 10. 01:04 PM - Re: Annunciator HELP! (Fiveonepw@aol.com) 11. 01:17 PM - Re: Annunciator HELP! (Fiveonepw@aol.com) 12. 01:38 PM - Re: Annunciator HELP! (Richard Tasker) 13. 02:03 PM - Re: Annunciator HELP! (john@ballofshame.com) 14. 02:50 PM - Re: Annunciator HELP! (The Kuffels) 15. 04:19 PM - Re: Annunciator HELP! (Richard Tasker) 16. 04:19 PM - Re: Runaway trim (marcausman) 17. 06:10 PM - Re: Annunciator HELP! (Fiveonepw@aol.com) 18. 06:28 PM - FET vs. NPN (was HELP!) (Fiveonepw@aol.com) 19. 08:59 PM - Re: FET vs. NPN (was HELP!) (Richard E. Tasker) 20. 09:35 PM - Re: FET vs. NPN (was HELP!) (Fiveonepw@aol.com) ________________________________ Message 1 _____________________________________ Time: 05:36:27 AM PST US From: "Greg Campbell" Subject: Re: AeroElectric-List: Runaway trim I still advocate a simple DPDT switch of the ON-OFF-(ON) variety as the best "last resort" trim disconnect and reverser. Most trim systems boil down to this: Power -> Trim Controls -> 2 wires -> Trim Motor The fancier the controls - the more likely the problems. Especially if the fancy controls involve a lot of relays, etc.. Disconnecting a runaway trim system "quickly" is essential if all you can do is "stop" the runaway condition. But... if it's likely that you could "reverse" the runaway condition and then stop it it at a neutral trim setting - then even speed is of less concern. My contention is that you can do both: 1)quickly STOP, and 2) optionally REVERSE the runaway trim condition. All you have to do is add a DPDT ON-OFF-(ON) switch between the "Controls" and the Trim Motor. Power -> Controls -> Trim Disconnect & Reverser Switch -> 2 wires -> Trim Motor. With the handle in the: ON position - your normal trim controls command the trim motor OFF position - nothing goes to the trim motor (ON) position - the reverse signal gets sent to the trim motor. It's simple, it's testable, it's reversible. About the only thing it can't fix is a jammed trim motor. It borders on foolproof - but you don't want to underestimate the ability of fools. Yes - it adds to the "parts count", but it's only 1 part - and it's failure modes are pretty benign. If anybody sees any problems with my logic - I'd appreciate hearing about it. I've been flying it happily for 2+ years now. Greg ________________________________ Message 2 _____________________________________ Time: 06:33:37 AM PST US From: Subject: Re: AeroElectric-List: Runaway trim That was my solution as well Greg. Agree with you 100%. Bob McC >From: "Greg Campbell" >To: "aeroelectric-list@matronics.com" >Subject: Re: AeroElectric-List: Runaway trim >Date: Fri, 8 Jun 2007 08:33:21 -0400 > >I still advocate a simple DPDT switch of the ON-OFF-(ON) variety >as the best "last resort" trim disconnect and reverser. > >Most trim systems boil down to this: >Power -> Trim Controls -> 2 wires -> Trim Motor > >The fancier the controls - the more likely the problems. >Especially if the fancy controls involve a lot of relays, etc.. > >Disconnecting a runaway trim system "quickly" is essential if >all you can do is "stop" the runaway condition. > >But... if it's likely that you could "reverse" the runaway condition >and then stop it it at a neutral trim setting - then even speed is of less >concern. > > >My contention is that you can do both: 1)quickly STOP, and 2) optionally >REVERSE >the runaway trim condition. All you have to do is add a DPDT ON-OFF-(ON) >switch >between the "Controls" and the Trim Motor. >Power -> Controls -> Trim Disconnect & Reverser Switch -> 2 wires -> Trim >Motor. > >With the handle in the: >ON position - your normal trim controls command the trim motor >OFF position - nothing goes to the trim motor >(ON) position - the reverse signal gets sent to the trim motor. > >It's simple, it's testable, it's reversible. About the only thing it can't >fix is a jammed trim motor. >It borders on foolproof - but you don't want to underestimate the ability >of >fools. > >Yes - it adds to the "parts count", but it's only 1 part - and it's failure >modes are pretty benign. >If anybody sees any problems with my logic - I'd appreciate hearing about >it. I've been flying it >happily for 2+ years now. > >Greg ________________________________ Message 3 _____________________________________ Time: 07:41:01 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Annunciator HELP! At 12:10 AM 6/8/2007 -0400, you wrote: >This post is for the techno-weenies- all others delete NOW! > >Goal: Illuminate an annunciator light when TruTrak servos are OFF using >NKK LB series illuminated pushbutton: > >http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=360&M=LB25RKW01-5C-JC-RO > >This device is a DPDT PB with LED lamp, built-in resistor for the >LED. (Reason for using PB instead of simple lamp is provide built-in PTT >function with N.O. contacts. LED has its own +&- contacts on back of switch) > >Consultation with TruTrak reveals that the torque line (pin6) to either >servo can be used to sense when power is applied to the servo, thereby >providing the necessary input. They sent a drawing showing a 10K resistor >tied to this pin gating on a darlington transistor to provide the switch >(ground path) for a lamp. Good, but I need the light OFF when power is on >this pin. Please don't ask why, this is what I want to happen. > >I begged the list for guidance some time ago and Bob very generously >supplied sketches (THANKS!) for how to achieve this using a IRF510 MOSFET >to either (1) turn the lamp ON as TruTrak indicated, or (2) turn the lamp >OFF by connecting the MOSFET between a 470 ohm resistor supplying the LED >and ground, which I understand would essentially remove voltage from the >LED by shorting its supply voltage to ground. With 13 volts supplied, >this would be about 30mA through the MOSFET when it is gated on, probably >not resulting in a new-clee-ur event. Problem is, I assume Bob is >referring to the resistor normally used to control LED current and since >in the LB series switches this resistor is built into the LED, connecting >the MOSFET to the LED supply voltage would essentially result in a dead >short (minus MOSFET internal resistance) to ground. I'd surmise Mr. >MOSFET would melt? See if this helps: http://www.aeroelectric.com/Pictures/Schematics/FiveOnOnePW.jpg Bob . . . ________________________________ Message 4 _____________________________________ Time: 07:49:44 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Annunciator HELP! At 12:10 AM 6/8/2007 -0400, you wrote: >This post is for the techno-weenies- all others delete NOW! > >Goal: Illuminate an annunciator light when TruTrak servos are OFF using >NKK LB series illuminated pushbutton: > >http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=360&M=LB25RKW01-5C-JC-RO > >This device is a DPDT PB with LED lamp, built-in resistor for the >LED. (Reason for using PB instead of simple lamp is provide built-in PTT >function with N.O. contacts. LED has its own +&- contacts on back of switch) > >Consultation with TruTrak reveals that the torque line (pin6) to either >servo can be used to sense when power is applied to the servo, thereby >providing the necessary input. They sent a drawing showing a 10K resistor >tied to this pin gating on a darlington transistor to provide the switch >(ground path) for a lamp. Good, but I need the light OFF when power is on >this pin. Please don't ask why, this is what I want to happen. > >I begged the list for guidance some time ago and Bob very generously >supplied sketches (THANKS!) for how to achieve this using a IRF510 MOSFET >to either (1) turn the lamp ON as TruTrak indicated, or (2) turn the lamp >OFF by connecting the MOSFET between a 470 ohm resistor supplying the LED >and ground, which I understand would essentially remove voltage from the >LED by shorting its supply voltage to ground. With 13 volts supplied, >this would be about 30mA through the MOSFET when it is gated on, probably >not resulting in a new-clee-ur event. Problem is, I assume Bob is >referring to the resistor normally used to control LED current and since >in the LB series switches this resistor is built into the LED, connecting >the MOSFET to the LED supply voltage would essentially result in a dead >short (minus MOSFET internal resistance) to ground. I'd surmise Mr. >MOSFET would melt? See if this helps: http://www.aeroelectric.com/Pictures/Schematics/FiveOnOnePW.jpg Try the same technique as suggested before except the external resistor needs to be fairly low resistance and handle a bit of power . . . like just under 1 watt. The added resistance will make the internal LED a tad dimmer but I suspect not so much that it would be unsatisfactory. This is simpler than a relay and easier to fabricate. You can put all the stuff on a "perf board" from Radio Shack. They probably have all the parts too. Bob . . . ________________________________ Message 5 _____________________________________ Time: 09:54:05 AM PST US From: Richard Tasker Subject: Re: AeroElectric-List: Annunciator HELP! No offense to Bob or his design, but using a 1W resistor to dissipate 1W is not a recipe for a long and reliable life for the resistor. When we design electronics circuits we always de-rate components significantly, which Bob also normally does. I would suggest the attached circuit (I hope it attaches), all components of which are readily available at Radio Shack or a number of other component houses. While it uses a couple additional parts, they are cheap and easy to use. This circuit will do what you want and not dissipate much of anything in either state. Respectfully, Dick Tasker Robert L. Nuckolls, III wrote: > > > At 12:10 AM 6/8/2007 -0400, you wrote: > >> This post is for the techno-weenies- all others delete NOW! >> >> Goal: Illuminate an annunciator light when TruTrak servos are OFF >> using NKK LB series illuminated pushbutton: >> >> http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=360&M=LB25RKW01-5C-JC-RO >> >> >> This device is a DPDT PB with LED lamp, built-in resistor for the >> LED. (Reason for using PB instead of simple lamp is provide built-in >> PTT function with N.O. contacts. LED has its own +&- contacts on >> back of switch) >> >> Consultation with TruTrak reveals that the torque line (pin6) to >> either servo can be used to sense when power is applied to the servo, >> thereby providing the necessary input. They sent a drawing showing a >> 10K resistor tied to this pin gating on a darlington transistor to >> provide the switch (ground path) for a lamp. Good, but I need the >> light OFF when power is on this pin. Please don't ask why, this is >> what I want to happen. >> >> I begged the list for guidance some time ago and Bob very generously >> supplied sketches (THANKS!) for how to achieve this using a IRF510 >> MOSFET to either (1) turn the lamp ON as TruTrak indicated, or (2) >> turn the lamp OFF by connecting the MOSFET between a 470 ohm resistor >> supplying the LED and ground, which I understand would essentially >> remove voltage from the LED by shorting its supply voltage to >> ground. With 13 volts supplied, this would be about 30mA through the >> MOSFET when it is gated on, probably not resulting in a new-clee-ur >> event. Problem is, I assume Bob is referring to the resistor >> normally used to control LED current and since in the LB series >> switches this resistor is built into the LED, connecting the MOSFET >> to the LED supply voltage would essentially result in a dead short >> (minus MOSFET internal resistance) to ground. I'd surmise Mr. MOSFET >> would melt? > > > See if this helps: > > http://www.aeroelectric.com/Pictures/Schematics/FiveOnOnePW.jpg > > Try the same technique as suggested before except the external > resistor needs to be fairly low resistance and handle a bit of > power . . . like just under 1 watt. The added resistance will > make the internal LED a tad dimmer but I suspect not so much that > it would be unsatisfactory. This is simpler than a relay and > easier to fabricate. You can put all the stuff on a "perf board" > from Radio Shack. They probably have all the parts too. > > Bob . . . > > ________________________________ Message 6 _____________________________________ Time: 10:07:42 AM PST US Subject: Re: AeroElectric-List: Annunciator HELP! From: john@ballofshame.com Why not use 2 transistors to invert the signal instead? -John www.ballofshame.com > > > At 12:10 AM 6/8/2007 -0400, you wrote: > >>This post is for the techno-weenies- all others delete NOW! >> >>Goal: Illuminate an annunciator light when TruTrak servos are OFF using >>NKK LB series illuminated pushbutton: >> >>http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=360&M=LB25RKW01-5C-JC-RO >> >>This device is a DPDT PB with LED lamp, built-in resistor for the >>LED. (Reason for using PB instead of simple lamp is provide built-in PTT >>function with N.O. contacts. LED has its own +&- contacts on back of >> switch) >> >>Consultation with TruTrak reveals that the torque line (pin6) to either >>servo can be used to sense when power is applied to the servo, thereby >>providing the necessary input. They sent a drawing showing a 10K >> resistor >>tied to this pin gating on a darlington transistor to provide the switch >>(ground path) for a lamp. Good, but I need the light OFF when power is >> on >>this pin. Please don't ask why, this is what I want to happen. >> >>I begged the list for guidance some time ago and Bob very generously >>supplied sketches (THANKS!) for how to achieve this using a IRF510 MOSFET >>to either (1) turn the lamp ON as TruTrak indicated, or (2) turn the lamp >>OFF by connecting the MOSFET between a 470 ohm resistor supplying the LED >>and ground, which I understand would essentially remove voltage from the >>LED by shorting its supply voltage to ground. With 13 volts supplied, >>this would be about 30mA through the MOSFET when it is gated on, probably >>not resulting in a new-clee-ur event. Problem is, I assume Bob is >>referring to the resistor normally used to control LED current and since >>in the LB series switches this resistor is built into the LED, connecting >>the MOSFET to the LED supply voltage would essentially result in a dead >>short (minus MOSFET internal resistance) to ground. I'd surmise Mr. >>MOSFET would melt? > > See if this helps: > > http://www.aeroelectric.com/Pictures/Schematics/FiveOnOnePW.jpg > > Try the same technique as suggested before except the external > resistor needs to be fairly low resistance and handle a bit of > power . . . like just under 1 watt. The added resistance will > make the internal LED a tad dimmer but I suspect not so much that > it would be unsatisfactory. This is simpler than a relay and > easier to fabricate. You can put all the stuff on a "perf board" > from Radio Shack. They probably have all the parts too. > > Bob . . . > > ________________________________ Message 7 _____________________________________ Time: 11:28:36 AM PST US Subject: Re: AeroElectric-List: Annunciator HELP! From: Ron Quillin At 09:51 6/8/2007, you wrote: >No offense to Bob or his design, but using a 1W resistor to >dissipate 1W is not a recipe for a long and reliable life for the >resistor. When we design electronics circuits we always de-rate >components significantly, which Bob also normally does. Here's a link to an Ohmite pdf used for selecting and derating resistors. http://ohmite.com/cgi-bin/showpage.cgi?product=appnotes_res_select.pdf&kw=resistor_selection__pdf_version_only_ The chart suggests no altitude derating below 5000 ft, increasing to ~.84 at FL250. Other derating factors and a good old-fashioned nomograph is even included. That one watt device really won't be happy with ~14 volts across it. Ron Q. ________________________________ Message 8 _____________________________________ Time: 12:12:49 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Annunciator HELP! At 12:51 PM 6/8/2007 -0400, you wrote: >No offense to Bob or his design, but using a 1W resistor to dissipate 1W >is not a recipe for a long and reliable life for the resistor. When we >design electronics circuits we always de-rate components significantly, >which Bob also normally does. > >I would suggest the attached circuit (I hope it attaches), all components >of which are readily available at Radio Shack or a number of other >component houses. While it uses a couple additional parts, they are cheap >and easy to use. This circuit will do what you want and not dissipate >much of anything in either state. > >Respectfully, > >Dick Tasker That works too. The 220 ohm was running a bit warm. 270 would be better. Bob . . . ________________________________ Message 9 _____________________________________ Time: 12:40:21 PM PST US From: Fiveonepw@aol.com Subject: Re: AeroElectric-List: Annunciator HELP! In a message dated 6/8/2007 9:44:21 AM Central Daylight Time, nuckollsr@cox.net writes: See if this helps: http://www.aeroelectric.com/Pictures/Schematics/FiveOnOnePW.jpg >>> Helps?! Now I have no excuse to not get this puppy done- Bless yore punkin' heart, Bob- once again the muddy waters become crystaline! VERY much appreciate the assist! Mark do not archive ************************************** See what's free at http://www.aol.com. ________________________________ Message 10 ____________________________________ Time: 01:04:45 PM PST US From: Fiveonepw@aol.com Subject: Re: AeroElectric-List: Annunciator HELP! In a message dated 6/8/2007 9:52:21 AM Central Daylight Time, nuckollsr@cox.net writes: The added resistance will make the internal LED a tad dimmer Probably not a problem, but if necessary NKK offers internal LEDs w/o the resistor, but was hoping to keep all annunciator PBs the same. Power to these lamps is via a PWM dimmer... _http://fdatasystems.com/LC_40.htm_ (http://fdatasystems.com/LC_40.htm) ...which they claim is "low frequency" without giving actual freq. My reading indicates MOSFETs operate well even at high freqs, so I suspect not a problem. Would this affect operation in any way i.e. extra heat? With MOSFET on and dimmer at full power, current should be about 64 mA or about .9watts (if my bad math is close)- should I heatsink this thing or can I just screw it to a support rib behind the panel (with a dab of h/s compound) with short wires (pigtail) soldered to legs, covered in heatshrink to insulate them? Thanks again! Mark ************************************** See what's free at http://www.aol.com. ________________________________ Message 11 ____________________________________ Time: 01:17:46 PM PST US From: Fiveonepw@aol.com Subject: Re: AeroElectric-List: Annunciator HELP! In a message dated 6/8/2007 12:10:40 PM Central Daylight Time, john@ballofshame.com writes: Why not use 2 transistors to invert the signal instead? Hi John- As you likely noticed I can't even get my mind around ONE of the stupid things- could you elaborate? Better yet, send me a schematic, part#s etc. - I'm in full learn mode... Appreciate the interest- Mark do not archive ************************************** See what's free at http://www.aol.com. ________________________________ Message 12 ____________________________________ Time: 01:38:54 PM PST US From: Richard Tasker Subject: Re: AeroElectric-List: Annunciator HELP! It runs at approximately 170-180 Hz. Dick Tasker Fiveonepw@aol.com wrote: > In a message dated 6/8/2007 9:52:21 AM Central Daylight Time, > nuckollsr@cox.net writes: > > The added resistance will > make the internal LED a tad dimmer > > Probably not a problem, but if necessary NKK offers internal LEDs w/o > the resistor, but was hoping to keep all annunciator PBs the same. > > Power to these lamps is via a PWM dimmer... > > http://fdatasystems.com/LC_40.htm > > ...which they claim is "low frequency" without giving actual freq. My > reading indicates MOSFETs operate well even at high freqs, so I > suspect not a problem. Would this affect operation in any way i.e. > extra heat? > > With MOSFET on and dimmer at full power, current should be about 64 mA > or about .9watts (if my bad math is close)- should I heatsink this > thing or can I just screw it to a support rib behind the panel (with a > dab of h/s compound) with short wires (pigtail) soldered to legs, > covered in heatshrink to insulate them? > > Thanks again! > Mark > > > ------------------------------------------------------------------------ > See what's free at AOL.com > . > >* > > >* > ________________________________ Message 13 ____________________________________ Time: 02:03:46 PM PST US Subject: Re: AeroElectric-List: Annunciator HELP! From: john@ballofshame.com Actually, there was an e-mail that went out around the same time as mine that actually had a schematic for such thing. I don't have all my e-mail in front of me so I can't point you to it unfortunately but now that I mentioned it you probably know exactly what I'm talking about (my apologies for not being able to credit whoever drew the schematic). The schematic showed regular transitors, I think. Bob had suggested a FET, albeit in a slightly different application. I don't know enough about the problem to really have an educated opinion on which is "better". Maybe those two can duke it out and converge to the optimal solution. -John www.ballofshame.com > > In a message dated 6/8/2007 12:10:40 PM Central Daylight Time, > john@ballofshame.com writes: > > Why not use 2 transistors to invert the signal instead? > > Hi John- As you likely noticed I can't even get my mind around ONE of the > stupid things- could you elaborate? Better yet, send me a schematic, > part#s etc. > - I'm in full learn mode... > > Appreciate the interest- > Mark do not archive > > > ************************************** See what's free at > http://www.aol.com. > ________________________________ Message 14 ____________________________________ Time: 02:50:45 PM PST US From: The Kuffels Subject: Re: AeroElectric-List: Annunciator HELP! Also <> or the several components of Dick Tasker < can't even get my mind around ONE of the stupid things- could you elaborate? Better yet, send me a schematic, part#s etc>> but wouldn't the following work? Change Bob's 220 (or 270) ohm resistor to 5k or maybe even 10k. Insert one identical FET between the resistor and the switch. The junction of the 1st Drain and the replaced resistor goes to the gate of the 2nd FET. The drain of the 2nd FET is connected to lamp power (as is the high end of the replaced resistor), the source goes to the high input of the switch LED. The other end of the switch LED goes to ground as in the original circuit. So when the TruTrak pin 6 is high the 1st FET conducts. The current through the new resistor lowers the voltage to the 2nd FET's gate and turns it off, turning off the lamp. When the pin 6 is low the 1st FET is off. Lamp power high goes through the 5k resistor to the 2nd FET gate and turns it on, turning on the switch LED. This eliminates the dimming of the lamp by running its power through a high wattage resistor. Don't have the facilities to draw and attach a schematic but the change to Bob's drawing is hopefully simple enough to be clear. Tom Kuffel AL7AU ________________________________ Message 15 ____________________________________ Time: 04:19:34 PM PST US From: Richard Tasker Subject: Re: AeroElectric-List: Annunciator HELP! Kinda like this if you like FETs better... Both schematics attached. Dick Tasker The Kuffels wrote: > > > Also <> or the several components of > Dick Tasker < can't even get my mind around ONE of the stupid things- > could you elaborate? Better yet, send me a schematic, part#s etc>> > but wouldn't the following work? > > Change Bob's 220 (or 270) ohm resistor to 5k or maybe even 10k. > Insert one identical FET between the resistor and the switch. The > junction of the 1st Drain and the replaced resistor goes to the gate > of the 2nd FET. The drain of the 2nd FET is connected to lamp power > (as is the high end of the replaced resistor), the source goes to the > high input of the switch LED. The other end of the switch LED goes to > ground as in the original circuit. > > So when the TruTrak pin 6 is high the 1st FET conducts. The current > through the new resistor lowers the voltage to the 2nd FET's gate and > turns it off, turning off the lamp. When the pin 6 is low the 1st FET > is off. Lamp power high goes through the 5k resistor to the 2nd FET > gate and turns it on, turning on the switch LED. This eliminates the > dimming of the lamp by running its power through a high wattage resistor. > > Don't have the facilities to draw and attach a schematic but the > change to Bob's drawing is hopefully simple enough to be clear. > > Tom Kuffel > AL7AU > > ________________________________ Message 16 ____________________________________ Time: 04:19:34 PM PST US Subject: AeroElectric-List: Re: Runaway trim From: "marcausman" john(at)ballofshame.com wrote: > > Another thing to consider which I haven't seen anyone do is a warning tone whenever the trim or flaps are energized. -John > www.ballofshame.com John, you haven't looked hard enough. :o The Vertical Power system shows on the pilot display when either trim or flaps is running, and will have audio tones as well. There are no mechanical relays - each flap and trim control circuit uses two solid state switches in series, so that if one fails you don't have a runaway condition. We also stop the motor if opposite trim or flap is commanded - so if the down trim wire shorts for example, you press the up trim button and the motor stops. Hold this for 3 seconds and the trim switch is disconnected. You can then run the trim & flaps from the display (using the soft keys) as a backup. We also suggest putting a mechanical switch in line with the trim motor as an additional disconnect if you so choose. Runaway trim is a very bad condition, and we really wanted to design a system that makes electric trim safe yet easy to wire. Come by and take a look at OSH. -------- Marc Ausman http://www.verticalpower.com RV-7 IO-390 Flying Read this topic online here: http://forums.matronics.com/viewtopic.php?p=117391#117391 ________________________________ Message 17 ____________________________________ Time: 06:10:38 PM PST US From: Fiveonepw@aol.com Subject: Re: AeroElectric-List: Annunciator HELP! In a message dated 6/8/2007 4:07:04 PM Central Daylight Time, john@ballofshame.com writes: Actually, there was an e-mail that went out around the same time as mine that actually had a schematic for such thing. >>> Yeah, it was that Dick Tasker guy- if I understand it correctly, looks like a neat arrangement... Thanks for the interest! Mark do not archive ************************************** See what's free at http://www.aol.com. ________________________________ Message 18 ____________________________________ Time: 06:28:23 PM PST US From: Fiveonepw@aol.com Subject: AeroElectric-List: FET vs. NPN (was HELP!) >>>>Kinda like this if you like FETs better... Both schematics attached. Since we are now knee-deep in this, pros-cons on MOSFET called out in Bob's original design (IRF510- assume this is component compatible to Kuffel suggestion?) and 2N2222 transistor- cost, mounting considerations, efficiency etc? Or not really a big deal as either are good choices? Great stuff- you guys are the best! (xoxoxoxo 8-)) Mark do not archive ************************************** See what's free at http://www.aol.com. ________________________________ Message 19 ____________________________________ Time: 08:59:58 PM PST US From: "Richard E. Tasker" Subject: Re: AeroElectric-List: FET vs. NPN (was HELP!) The two transistor (bipolar or FET) approach is slightly better (in my opinion) than the single transistor approach in that it doesn't draw significant currents except when the LED is on. The single transistor approach is somewhat of a compromise since it has to draw a relatively significant current to keep the LED off. If you had the LED with no built-in series resistor it would be better, but would still be somewhat less desirable. As far as using a bipolar transistor vs a FET, that is pretty much up to user preference. I suppose a slight case could be made for the bipolar transistor being less susceptible to static electricity handling problems, but with a tiny bit of care, that is moot. This is not to say that there are not cases when one or the other is definitely preferable, but for the circuit in question it really makes no practical difference. Dick Tasker Fiveonepw@aol.com wrote: > >>>>Kinda like this if you like FETs better... Both schematics attached. > > Since we are now knee-deep in this, pros-cons on MOSFET called out in > Bob's original design (IRF510- assume this is component compatible to > Kuffel suggestion?) and 2N2222 transistor- cost, mounting > considerations, efficiency etc? > > Or not really a big deal as either are good choices? > > Great stuff- you guys are the best! (xoxoxoxo 8-)) > > Mark do not archive > > > ------------------------------------------------------------------------ > See what's free at AOL.com > . > >* > > >* > -- 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 20 ____________________________________ Time: 09:35:15 PM PST US From: Fiveonepw@aol.com Subject: Re: AeroElectric-List: FET vs. NPN (was HELP!) In a message dated 6/8/2007 11:02:57 PM Central Daylight Time, retasker@optonline.net writes: for the circuit in question it really makes no practical difference. >>> Thanks again as always, sir! 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