---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 06/21/11: 20 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:54 AM - Southbridge Airport Tornado Damage. (Eric M. Jones) 2. 09:44 AM - PTT buzz (Dan Billingsley) 3. 12:01 PM - IvoProp current limiter -revisit (Mike Welch) 4. 12:28 PM - Re: IvoProp current limiter -revisit (Robert L. Nuckolls, III) 5. 01:23 PM - Re: PTT buzz (Dan Billingsley) 6. 01:49 PM - Re: PTT buzz (Robert L. Nuckolls, III) 7. 03:05 PM - push to test circuit for differing loads (pmnewlon) 8. 04:06 PM - Re: push to test circuit for differing loads (Jeff Luckey) 9. 05:33 PM - Re: PTT buzz (Dan Billingsley) 10. 06:15 PM - IvoProp current limiter -revisit (Dennis & Anne Glaeser) 11. 06:59 PM - Re: IvoProp current limiter -revisit (Mike Welch) 12. 07:06 PM - Re: PTT buzz (Robert L. Nuckolls, III) 13. 07:24 PM - Re: IvoProp current limiter -revisit (Robert L. Nuckolls, III) 14. 07:45 PM - Re: IvoProp current limiter -revisit (Deems Herring) 15. 07:55 PM - Re: push to test circuit for differing loads (Robert L. Nuckolls, III) 16. 08:21 PM - Re: IvoProp current limiter -revisit (Mike Welch) 17. 08:32 PM - Re: push to test circuit for differing loads (Vern Little) 18. 09:15 PM - Re: IvoProp current limiter -revisit (Robert L. Nuckolls, III) 19. 09:15 PM - Re: IvoProp current limiter -revisit (Robert L. Nuckolls, III) 20. 10:00 PM - Re: push to test circuit for differing loads (Jeff Luckey) ________________________________ Message 1 _____________________________________ Time: 05:54:33 AM PST US Subject: AeroElectric-List: Southbridge Airport Tornado Damage. From: "Eric M. Jones" I finally went up to the airport and spoke to Jim Latour, the manager. The tornado destroyed 15 airplanes, not including an almost completed and not-insured RV that just went into the new hangar...now totally destroyed. There had been a lot of cleanup in the week since the twister. I live a couple miles from 3BO, and there was hardly a breath of wind. Hummingbirds were happy at the feeder. Great sadness. The path of destruction was very narrow. A block away from the path was unaffected. In the path, oak trees two feet in diameter were broken like match-sticks....shredded by a billion HP weed-whacker. See attached. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones@charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=343630#343630 Attachments: http://forums.matronics.com//files/p1000226_741.jpg http://forums.matronics.com//files/p1000228_595.jpg http://forums.matronics.com//files/p1000233_134.jpg http://forums.matronics.com//files/p1000238_209.jpg ________________________________ Message 2 _____________________________________ Time: 09:44:46 AM PST US From: Dan Billingsley Subject: AeroElectric-List: PTT buzz I just finished wiring the Ray Allen G205 stick in conjunction w/ Garmin SL40 radio and the intercom PM1000 (PS Engineering). Turning it all on and headphone jacks connected...I talk into mic and hear loud and clear. When I key the PTT, I immediately get a pulsating buzz. I release, it goes away. Could this be a ground loop? don't know...never heard this b-4. Thanks, Dan B ________________________________ Message 3 _____________________________________ Time: 12:01:30 PM PST US From: Mike Welch Subject: AeroElectric-List: IvoProp current limiter -revisit Bob N=2C Quite a while back I built and installed the IvoProp current limiter circ uit you desgned. By all account=2C it appears to work=2C with one significant exception=3B i t cuts out very quickly when cycling in either direction. In other words=2C the blades barely move at all. Yes=2C the LEDs light up=2C and all other aspects of the circuit appear t o function properly. The only weakness is the extreme shortage of blade movement. I know the ob vious=2C question is=3B do we know if the blades are free to mover properly? As far as I kno w=2C yes=2C they used to work just fine=2C prior to the installation of the current limiter circuit. Bob=2C is it possible to "vary" the circuit's current limitation. Exampl e....if the present resistors that control the circuit's current to "top out" at such and such amps=2C wo uld it be reasonable to redesign the circuit to allow for 'differing" overloads. Do you get what I 'm trying to say? By watching the entire system (circuit=2C prop blades/motor=2C etc)=2C th e circuit appears to operate as it was designed=2C except that it appears to cut out at 1=2C may be 2 amps. I have to run off to Minneapolis for a few days=2C but when I get back=2C I'll hook up a highly accurate ammeter in the present arrangement=2C and see exactly how m uch current shuts it off. Any ideas=2C or suggestions are highly appreciated. Thanks=2C Mike Welch ________________________________ Message 4 _____________________________________ Time: 12:28:19 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: IvoProp current limiter -revisit At 02:56 PM 6/21/2011, you wrote: >Bob N, > > Quite a while back I built and installed the IvoProp current > limiter circuit you desgned. >By all account, it appears to work, with one significant exception; >it cuts out very quickly >when cycling in either direction. In other words, the blades barely >move at all. Okay, just so folks know what we're talking about here's a recap of the circuit and design goals for the system Mike has crafted: ----------------------- http://aeroelectric.com/Pictures/Schematics/IVO-Prop_Pitch_Controller.pdf Design goals: Provide absolute current limit on the order of 9A: Q114 is a power FET that saturates with bias through R104, R105 and D109 when power is applied through "M" connections that sense motor power. Voltage drop across R117/R118 is monitored through R116 causing Q115 to turn on when drop across the R117/118 exceeds Vbe of Q115. This is approx .6 volts. When Q115 turns on, it starves Q114 of gate drive and causes it to become a constant current generator with calibration set by the combination of R117/R118. Any time the constant current loop is active, LED D109 will be illuminated. D109 will flash each time the prop pitch motor is energized and the system becomes an active inrush current limiter. Limit the duration of the current limit mode to 100-200 mS whereupon the system goes open circuit and removes power from the motor: At any time the current limiter is active, Q115 collector current through R105 will turn on Q103 causing the collector to pull up to the supply rail. This causes C112 to charge through R106 until zener D110 conducts at about 8V. This event will occur approximately 120 mS after onset of current limit. When D110 conducts, it pulls the base of Q115 more positive causing the Q115/Q103 pair to "latch up" not unlike an SCR. When the latching event occurs, the collector of Q115 pulls to a few millivolts above ground depriving Q114 of all gate drive. Normal operation: D109 will flash each time the motor control switch is closed due to motor inrush current being electronically limited. D109 will also flash a bit longer (about 120 mS) when the prop pitch motor reaches the mechanical stop and the current limit is invoked. As long as the prop pitch motor is powered D108 will be illuminated. When the prop pitch system reaches a mechanical limit and the control switch is NOT relaxed, D019 flashes for about 120 mS and D108 goes dark. Releasing the motor control switch removes power from the latching loop and discharges C112 through R119, R104, BC junction Q103, and R106. The system spends so little time in I-limit mode that Q114 does not require a heat-sink. D109 and D108 staying on together indicates a malfunction and the motor control switch needs to be released within a second or so to avoid over-heat damage to Q114. -------------------- > Yes, the LEDs light up, and all other aspects of the circuit > appear to function properly. >The only weakness is the extreme shortage of blade movement. I know >the obvious, question >is; do we know if the blades are free to mover properly? As far as >I know, yes, they >used to work just fine, prior to the installation of the current >limiter circuit. The green LED should be illuminated when the pitch motor is being commanded and the system is NOT in a current limited mode. If the motor hits the stop and current spikes, the current limit mode kicks in. The green LED should dim or go dark . . . the amber LED should illuminate saying that current limiting operation is in effect. One should release the switch quickly after the amber LED comes on. > By watching the entire system (circuit, prop blades/motor, etc), > the circuit appears to >operate as it was designed, except that it appears to cut out at 1, >maybe 2 amps. Had you tested this before? With the values selected for R117 and R118, current limit should be on the order of 10 amps. If your 'stalled' current is 2A, then the current limit is kicking in MUCH to low. > I have to run off to Minneapolis for a few days, but when I get > back, I'll hook up a >highly accurate ammeter in the present arrangement, and see exactly >how much current >shuts it off. Good lick. But be cautious about this measurement. The TIME that the Q114 can stand to run at 10A (140 watts) is limited by the size of heat-sink it enjoys. Normal operations will have you releasing the switch within a second or so of having the amber light come on so when things are working right, a large heat-sink is not needed. Experimental measurements are another matter. Be quick. > Bob, is it possible to "vary" the circuit's current > limitation. Example....if the present resistors >that control the circuit's current to "top out" at such and such >amps, would it be reasonable to >redesign the circuit to allow for 'differing" overloads. Do you get >what I'm trying to say? Yes but . . . this does not appear to be the root cause of symptoms you're observing. Bob . . . ________________________________ Message 5 _____________________________________ Time: 01:23:49 PM PST US From: Dan Billingsley Subject: Re: AeroElectric-List: PTT buzz I think I found the ghost...When I first heard it it sounded like AC cycling (the noise was very consistant). AFter going thru this symptom with a few folks...Garmin techs saying they never heard of it b-4... I was scratching my head and looked up. The antenna was hovering between two floursent lights in the garage...it WAS AC! Dan --- On Tue, 6/21/11, Dan Billingsley wrote: > From: Dan Billingsley > Subject: AeroElectric-List: PTT buzz > To: aeroelectric-list@matronics.com > Date: Tuesday, June 21, 2011, 10:40 AM > --> AeroElectric-List message > posted by: Dan Billingsley > > I just finished wiring the Ray Allen G205 stick in > conjunction w/ Garmin SL40 radio and the intercom PM1000 (PS > Engineering). Turning it all on and headphone jacks > connected...I talk into mic and hear loud and clear. When I > key the PTT, I immediately get a pulsating buzz. I release, > it goes away. > Could this be a ground loop? don't know...never heard this > b-4. > Thanks, > Dan B > > AeroElectric-List Email Forum - > FAQ, > - MATRONICS WEB FORUMS - > List Contribution Web Site - > -Matt > Dralle, List Admin. > > > > ________________________________ Message 6 _____________________________________ Time: 01:49:38 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: PTT buzz At 04:18 PM 6/21/2011, you wrote: > > >I think I found the ghost...When I first heard it it sounded like AC >cycling (the noise was very consistant). AFter going thru this >symptom with a few folks...Garmin techs saying they never heard of it b-4... >I was scratching my head and looked up. The antenna was >hovering between two floursent lights in the garage...it WAS AC! >Dan Hmmmm . . . good hypothesis. If you turn off the lights does the buzz go away? Bob . . . ________________________________ Message 7 _____________________________________ Time: 03:05:46 PM PST US Subject: AeroElectric-List: push to test circuit for differing loads From: "pmnewlon" I posted on VAF yesterday and got a partial answer to my question there, which caused me to have more questions so I thought I better get to the right place! I have seven annunciator LEDs on my panel; as it turns out all but one switch the positive side of the LED but one switches the ground. I understand how to arrange diodes in a push to test circuit if all the LEDs are switched the same way but cannot find an example of a circuit where there is a mixture of ground and positive switching with a single push to test button. The response to my post on VAF suggested a double pole push button but I have not found a suitably small DPST (ON) device. I'd really like to make the circuit with a small SPST (ON) pushbutton but am short on the circuit knowledge. Does anyone have a reference diagram of such a circuit that I could 'borrow'? Thanks! Phil Read this topic online here: http://forums.matronics.com/viewtopic.php?p=343682#343682 ________________________________ Message 8 _____________________________________ Time: 04:06:23 PM PST US From: "Jeff Luckey" Subject: RE: AeroElectric-List: push to test circuit for differing loads Phil, Just off the top of my head (and without having seen a schematic of your particular setup) I'd say that what you're asking for is not possible. In a single pole you could handle the ground legs of the test circuit (with proper isolation diodes as you mentioned) or the high-side circuit, but not both. But I have another suggestion: You could add a small 2-pole relay to manage the LED test circuitry and control its coil w/ your SPST pushbutton. There are all kinds of cheap, circuit board mountable, smaller-than-a-sugar-cube relays that could do the job (I don't have part numbers available to me at the moment). -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of pmnewlon Sent: Tuesday, June 21, 2011 15:02 Subject: AeroElectric-List: push to test circuit for differing loads I posted on VAF yesterday and got a partial answer to my question there, which caused me to have more questions so I thought I better get to the right place! I have seven annunciator LEDs on my panel; as it turns out all but one switch the positive side of the LED but one switches the ground. I understand how to arrange diodes in a push to test circuit if all the LEDs are switched the same way but cannot find an example of a circuit where there is a mixture of ground and positive switching with a single push to test button. The response to my post on VAF suggested a double pole push button but I have not found a suitably small DPST (ON) device. I'd really like to make the circuit with a small SPST (ON) pushbutton but am short on the circuit knowledge. Does anyone have a reference diagram of such a circuit that I could 'borrow'? Thanks! Phil Read this topic online here: http://forums.matronics.com/viewtopic.php?p=343682#343682 ________________________________ Message 9 _____________________________________ Time: 05:33:59 PM PST US From: Dan Billingsley Subject: Re: AeroElectric-List: PTT buzz I didn't turn the lights off but I was able to roll the plane out from under the lights a ways. When I did that, the noise became less prominent. I will need to wait until I have an extra hand to roll the plane all the way out of the garage (The slope + gravity= plane in street). One of the guys I talked to today had a good point about when I key the mic inside the closed space I have quite a bit RF dancing back and forth in there. Would it be reasonable to say it could be some feedback interference as well? Dan --- On Tue, 6/21/11, Robert L. Nuckolls, III wrote: > From: Robert L. Nuckolls, III > Subject: Re: AeroElectric-List: PTT buzz > To: aeroelectric-list@matronics.com > Date: Tuesday, June 21, 2011, 2:45 PM > --> AeroElectric-List message > posted by: "Robert L. Nuckolls, III" > > At 04:18 PM 6/21/2011, you wrote: > Billingsley > > > > I think I found the ghost...When I first heard it it > sounded like AC cycling (the noise was very consistant). > AFter going thru this symptom with a few folks...Garmin > techs saying they never heard of it b-4... > > I was scratching my head and looked up. The antenna > was hovering between two floursent lights in the > garage...it WAS AC! > > Dan > > Hmmmm . . . good hypothesis. If you turn > off the lights > does the buzz go away? > > > Bob . . . > > AeroElectric-List Email Forum - > FAQ, > - MATRONICS WEB FORUMS - > List Contribution Web Site - > -Matt > Dralle, List Admin. > > > > ________________________________ Message 10 ____________________________________ Time: 06:15:56 PM PST US From: "Dennis & Anne Glaeser" Subject: AeroElectric-List: IvoProp current limiter -revisit Bob and Mike, I have been using Bob's circuit on my IVO and it works flawlessly. It's a simple and foolproof way to protect the gear train that drives the blade pitch mechanism. When I finished the circuit, Bob asked if I had access to an oscilloscope in order to verify it's operation. One of my EAA chapter members has one and we captured the traces per Bob's specs. Perhaps Mike could do the same thing and that might provide a clue as to what is (or isn't) happening. Bob's description says that when the current limit is reached, D108 (amber LED) flashed for 120 ms and D109 (green LED) goes dark. In my implementation, the amber LED stays lit as long as I hold the switch (the motor stops) - the green LED does go dark. I don't know if that is significant, but thought I'd mention it. When the motor is running, the green LED is on, but the amber LED is off (except for the flash at startup). If there is anything I can do to help, just let me know. Dennis Glaeser ________________________________ Message 11 ____________________________________ Time: 06:59:58 PM PST US From: Mike Welch Subject: RE: AeroElectric-List: IvoProp current limiter -revisit Bob=2C Thank you for the highly informative description of the circuit. I know to keep the toggle switch testing very brief=2C however=2C I did mount the FET on a 1 1 /2" X 2" piece of aluminum for a heat sink. The heat sink=2C and complete circuit is cont ained in a neat plastic box. After I get back from my mini-vacation=2C I'll do my best to test the cir cuit...carefully. I also verify the correct LEDs are lighting as you described. Thanks a bunch=2C I'll get back ya early next week. Mike Welch PS. Do they have fish in Minnesota? ________________________________ Message 12 ____________________________________ Time: 07:06:54 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: PTT buzz At 08:29 PM 6/21/2011, you wrote: > > >I didn't turn the lights off but I was able to roll the plane out >from under the lights a ways. When I did that, the noise became less >prominent. I will need to wait until I have an extra hand to roll >the plane all the way out of the garage (The slope + gravity= plane >in street). One of the guys I talked to today had a good point about >when I key the mic inside the closed space I have quite a bit RF >dancing back and forth in there. Would it be reasonable to say it >could be some feedback interference as well? Possible . . . but low risk. The lighting interference hypothesis is much stronger given that the noise changed when you moved. Modern fluorescent lamps not only generate noise from the cacophony of molecular noise in the gas filled tube, they feature electronic ballasts also renowned for their ability to 'sing' at a constellation of frequencies. I'm betting on the lights. Bob . . . ________________________________ Message 13 ____________________________________ Time: 07:24:22 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: IvoProp current limiter -revisit At 09:12 PM 6/21/2011, you wrote: >Bob and Mike, > >I have been using Bob=92s circuit on my IVO and it >works flawlessly. It=92s a simple and foolproof >way to protect the gear train that drives the blade pitch mechanism. > >When I finished the circuit, Bob asked if I had >access to an oscilloscope in order to verify >it=92s operation. One of my EAA chapter members >has one and we captured the traces per Bob=92s >specs. Perhaps Mike could do the same thing and >that might provide a clue as to what is (or isn=92t) happening. > >Bob=92s description says that when the current >limit is reached, D108 (amber LED) flashed for >120 ms and D109 (green LED) goes dark. In my >implementation, the amber LED stays lit as long >as I hold the switch (the motor stops) ' the >green LED does go dark. I don=92t know if that is >significant, but thought I=92d mention it. You bet. I'd forgotten how that thing was supposed to work. Q103/Q115 form a time-delayed latching switch that switches ON as soon as C112 charges up enough to cause D110 to go into conduction. Once the latch triggers, Q115 is held on 'saturated' until power is removed. > When the motor is running, the green LED is > on, but the amber LED is off (except for the flash at startup). So the amber LED flashes at start up indicating that the current limiter did its job while the motor spins up. When the system hits mechanical stops, the led will light again when current limit becomes active. A few milliseconds later, the latch trips and the motor current goes to zero. Green led goes dark. Amber LED stays lit. So my earlier admonition about being quick on the switch to avoid overheating Q114 is all wet. The time-delayed shut-down latch protects Q114. > >If there is anything I can do to help, just let me know. You just did. Thanks! If there's enough interest in this device, it could be packaged up nicely in a box like this: Emacs! Since you guys did all the development and proof of concept work, it would only take a couple hours to package it up and add it to the product line. We could also make this a DIY project and sell the ECB, case and connector hardware. Bob . . . ________________________________ Message 14 ____________________________________ Time: 07:45:05 PM PST US From: Deems Herring Subject: RE: AeroElectric-List: IvoProp current limiter -revisit I will take 2 Deems If there's enough interest in this device=2C it could be packaged up nicely in a box like this: Since you guys did all the development and proof of concept work=2C it would only take a couple hours to package it up and add it to the product line. We could also make this a DIY project and sell the ECB=2C case and connector hardware. Bob . . . ________________________________ Message 15 ____________________________________ Time: 07:55:46 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: push to test circuit for differing loads At 06:01 PM 6/21/2011, you wrote: > >I posted on VAF yesterday and got a partial answer to my question >there, which caused me to have more questions so I thought I better >get to the right place! > >I have seven annunciator LEDs on my panel; as it turns out all but >one switch the positive side of the LED but one switches the >ground. I understand how to arrange diodes in a push to test >circuit if all the LEDs are switched the same way but cannot find an >example of a circuit where there is a mixture of ground and positive >switching with a single push to test button. The response to my >post on VAF suggested a double pole push button but I have not found >a suitably small DPST (ON) device. I'd really like to make the >circuit with a small SPST (ON) pushbutton but am short on the >circuit knowledge. > >Does anyone have a reference diagram of such a circuit that I could 'borrow'? You betcha. Did this in some airplane wayyyyyyy back when. The annunciators were light bulbs instead of leds but the principal is the same. You can get the parts at Radio Shack . . . http://tinyurl.com/3lu334y The transistors operate saturated so given the intermittent duty service, will not require heat-sinks. Wire 'em up and truck on. You could probably get it to work fine with physically smaller transistors but these TO-200 devices are robust and easy to mount to a piece of perf-board. Bob . . . ________________________________ Message 16 ____________________________________ Time: 08:21:15 PM PST US From: Mike Welch Subject: RE: AeroElectric-List: IvoProp current limiter -revisit Thanks for the responses=2C guys. I really wish I had more time to try and figure it out right now=2C but I'll have to wait until next Monday or so=2C after I get b ack. I went out and did a quick cycle or two of the circuit=2C and the LEDs appe ar to turn on and off as Dennis describes. The pitch motor obviously is twisting the prop blades =2C but the whole thing still seems to be working exactly as it should=2C except it only has a one second range=2C from switch on to circuit off=2C maybe at most=2C two seconds! I did see that if I keep switching in the same direction=2C over and over =2C I can get the opposite direction to stay "lit" longer=2C getting it to twist for 3-4 seconds. I e ven kept "pressuring it"=2C and the 10A circuit breaker popped. I reset it=2C and everything still wor ked fine...just briefly. I'll know more after I get back. Thanks=2C Mike W ________________________________ Message 17 ____________________________________ Time: 08:32:11 PM PST US From: "Vern Little" Subject: Re: AeroElectric-List: push to test circuit for differing loads Check out the IL-4A or IL-12A on this site: http://vx-aviation.com/page_2.html The datasheet has the schematic for what you want if you feel like building your own. Thx, Vern Little Vx Aviation From: Robert L. Nuckolls, III Sent: Tuesday, June 21, 2011 7:52 PM Subject: Re: AeroElectric-List: push to test circuit for differing loads At 06:01 PM 6/21/2011, you wrote: I posted on VAF yesterday and got a partial answer to my question there, which caused me to have more questions so I thought I better get to the right place! I have seven annunciator LEDs on my panel; as it turns out all but one switch the positive side of the LED but one switches the ground. I understand how to arrange diodes in a push to test circuit if all the LEDs are switched the same way but cannot find an example of a circuit where there is a mixture of ground and positive switching with a single push to test button. The response to my post on VAF suggested a double pole push button but I have not found a suitably small DPST (ON) device. I'd really like to make the circuit with a small SPST (ON) pushbutton but am short on the circuit knowledge. Does anyone have a reference diagram of such a circuit that I could 'borrow'? You betcha. Did this in some airplane wayyyyyyy back when. The annunciators were light bulbs instead of leds but the principal is the same. You can get the parts at Radio Shack . . . http://tinyurl.com/3lu334y The transistors operate saturated so given the intermittent duty service, will not require heat-sinks. Wire 'em up and truck on. You could probably get it to work fine with physically smaller transistors but these TO-200 devices are robust and easy to mount to a piece of perf-board. Bob . . . ------------------------------------------------------------------------- ------- No virus found in this message. Checked by AVG - www.avg.com ________________________________ Message 18 ____________________________________ Time: 09:15:26 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: IvoProp current limiter -revisit At 11:17 PM 6/21/2011, you wrote: >Thanks for the responses, guys. I really wish I had more time to >try and figure it out >right now, but I'll have to wait until next Monday or so, after I get back. > >I went out and did a quick cycle or two of the circuit, and the LEDs >appear to turn on and off >as Dennis describes. The pitch motor obviously is twisting the prop >blades, but the whole >thing still seems to be working exactly as it should, except it only >has a one second range, >from switch on to circuit off, maybe at most, two seconds! > >I did see that if I keep switching in the same direction, over and >over, I can get the opposite >direction to stay "lit" longer, getting it to twist for 3-4 >seconds. I even kept "pressuring it", >and the 10A circuit breaker popped. I reset it, and everything >still worked fine...just briefly. Okay, if your 10A breaker popped, the motor/gearbox combo is drawing way too much current . . . for reasons as yet unknown. The limiter may well be doing what it was designed to do. Try taking it out of the circuit as described earlier and then measure the current. Bob . . . ________________________________ Message 19 ____________________________________ Time: 09:15:26 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: IvoProp current limiter -revisit At 10:42 PM 6/21/2011, you wrote: >I will take 2 > >Deems noted. thanks. Bob . . . ________________________________ Message 20 ____________________________________ Time: 10:00:57 PM PST US From: "Jeff Luckey" Subject: RE: AeroElectric-List: push to test circuit for differing loads Ok - devil's advocate here. Bob's schematic parts count: 2 transistors, 4 resistors = 6 components - or -- ONE small, 2-amp, DIP DPDT relay. Which way is stronger/better/faster/easier? _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Vern Little Sent: Tuesday, June 21, 2011 20:29 Subject: Re: AeroElectric-List: push to test circuit for differing loads Check out the IL-4A or IL-12A on this site: http://vx-aviation.com/page_2.html The datasheet has the schematic for what you want if you feel like building your own. Thx, Vern Little Vx Aviation From: Robert L. Nuckolls, III Sent: Tuesday, June 21, 2011 7:52 PM Subject: Re: AeroElectric-List: push to test circuit for differing loads At 06:01 PM 6/21/2011, you wrote: I posted on VAF yesterday and got a partial answer to my question there, which caused me to have more questions so I thought I better get to the right place! I have seven annunciator LEDs on my panel; as it turns out all but one switch the positive side of the LED but one switches the ground. I understand how to arrange diodes in a push to test circuit if all the LEDs are switched the same way but cannot find an example of a circuit where there is a mixture of ground and positive switching with a single push to test button. The response to my post on VAF suggested a double pole push button but I have not found a suitably small DPST (ON) device. I'd really like to make the circuit with a small SPST (ON) pushbutton but am short on the circuit knowledge. Does anyone have a reference diagram of such a circuit that I could 'borrow'? You betcha. Did this in some airplane wayyyyyyy back when. The annunciators were light bulbs instead of leds but the principal is the same. You can get the parts at Radio Shack . . . http://tinyurl.com/3lu334y The transistors operate saturated so given the intermittent duty service, will not require heat-sinks. Wire 'em up and truck on. You could probably get it to work fine with physically smaller transistors but these TO-200 devices are robust and easy to mount to a piece of perf-board. Bob . . . href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matro nics.com/Navigator?AeroElectric-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c _____ No virus found in this message. 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