---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 06/22/14: 19 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:23 AM - Re: LED Ghosting (donjohnston) 2. 05:47 AM - Re: LED Ghosting (user9253) 3. 06:14 AM - Re: Question about Electrically dependent engine and power based (user9253) 4. 06:32 AM - Re: How to decide if a heat sink is required for a Rect Bridge (Sprocket) 5. 06:51 AM - Re: Z14 question about adding in external power Piper style jack (user9253) 6. 06:58 AM - Re: LED Ghosting (donjohnston) 7. 07:07 AM - Re: Re: LED Ghosting (Richard Girard) 8. 07:28 AM - Re: Re: LED Ghosting (Eric Page) 9. 08:07 AM - Re: LED Ghosting (donjohnston) 10. 09:05 AM - Re: Re: LED Ghosting (Robert L. Nuckolls, III) 11. 09:14 AM - Re: Re: LED Ghosting (Robert L. Nuckolls, III) 12. 12:09 PM - Re: LED Ghosting (donjohnston) 13. 03:13 PM - Re: How to decide if a heat sink is required for a Rect Bridge (Jeffrey W. Skiba) 14. 03:43 PM - Re: Re: LED Ghosting (Robert L. Nuckolls, III) 15. 04:49 PM - Re: LED Ghosting (donjohnston) 16. 06:48 PM - Re: How to decide if a heat sink is required for a Rect Bridge (Robert L. Nuckolls, III) 17. 06:49 PM - Re: Re: LED Ghosting (Robert L. Nuckolls, III) 18. 07:47 PM - Re: LED Ghosting (donjohnston) 19. 09:09 PM - Re: How to decide if a heat sink is required for a Rect Bridge (Jeffrey W. Skiba) ________________________________ Message 1 _____________________________________ Time: 05:23:41 AM PST US Subject: AeroElectric-List: Re: LED Ghosting From: "donjohnston" Here's (what I think is) the correct circuit. Still not sure I can integrate this into the existing PCB though. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425262#425262 Attachments: http://forums.matronics.com//files/led_circuit_3_102.pdf ________________________________ Message 2 _____________________________________ Time: 05:47:26 AM PST US Subject: AeroElectric-List: Re: LED Ghosting From: "user9253" Your LED circuit 3.pdf looks correct to me. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425266#425266 ________________________________ Message 3 _____________________________________ Time: 06:14:33 AM PST US Subject: AeroElectric-List: Re: Question about Electrically dependent engine and power based From: "user9253" There is more than one way to wire an electrically dependent engine. The important thing is that no single failure will stop the engine. The designer must look at each component and ask, "If this part fails, what will happen and what is the backup plan." Connecting directly to the battery eliminates some failure points, but still leaves the battery connections. If you want to get engine power from a different location than the battery bus, that is OK as long as there is a plan B in case something fails. Plan B should preferably include automatic (diodes) switching to another source or to another path from a single source. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425268#425268 ________________________________ Message 4 _____________________________________ Time: 06:32:09 AM PST US From: Sprocket Subject: Re: AeroElectric-List: How to decide if a heat sink is required for a Rect Bridge It looks like you will only dissipate about 5 watts continuous power, which i s well within the capability of the device. However, when you mount it, put about a 3x3 piece of .063 aluminum underneath as a heat spreader to protect the composite surface. Use a tiny amount of thermal grease between the cas e and heat spreader. Vern ========================== ========================== Sent from my iThing. It is responsible for all gramma and typo terrors. > On Jun 21, 2014, at 10:25 PM, "Jeffrey W. Skiba" wrote: > > Okay I have these Rect Bridge > GBPC Series > Digikey gbpc3502a > > 35 amp version > > > I plan I using them to connect a device from two different dc batteries > To run a load of about 6 amps continuous > This is a composite airframe so no place to bolt directly to metal > > 1) Is a heat sink required ? > 2) Would it be a good idea if one is not required > 3) How do we tell how big of a heat sink we need ? > > > Would a digikey part number hs114 work properly ? > How can we tell ? > > Thanks > Jeff. > =C2=C2=B7=BA~=B0=C3=AD=C2=B2,=C3=9E=C3=99=C3=8A%=C2=A2=C2=BD 4=C3=93M4}=C2=A7=1Er=B9=C2=AB=B0=C3=C3=A7{=07(=C2=BA=C2=B8=C5 =BE=C2=AD8^=01=C3=C3=A8=12W=C5=93=C2=B6=C2=B8=C5=93.+-=12f=C2=A2=9D Z+=C2=BAe,z=C3=98^1=C2=ABk=C2=A2x=C5=93=C2=B0=C2=B8=C2=AC=C2=B4W=C5=A1=C2=B6 =C3=C3=9E=C2=B0=C3'=C2=AF=C5-=06=C2=AD=C2=A2=C2=BBhn=C2=BA0=C2=B1=C3=AB azf=C2=A7=C3=88=C2=B8=C2=AC=C2=B6=C3=ABb=93+bz=C3=8B.r=16=C2=AC.+-R=7F =C3=92=C2=B9=C2=BB=1C=C2=AE*m=C5-=B0=C3=C2=AD=C3=88b=C2=BD=C3=A4=C5 =BEj=C2=B7!=0E=C5=92'=93-=C2=9D=C3=AC6=C2=B2=06=C2=BA0=C2=B1=C3 -=C2=A1j=C3=91@@=C3=B8h=C2=B6=B9!j=C2=B7=C5=A1=C2=9D=C3=99=C2=AEr=19 =C2=AEr=19=C2=A8=C2=AD=C3=C2=A1=C2=AD=C3=A7=C3=A1=C2=B6=C3=9A=7F=C3=0C 0=84=A2=C2=ABk=C2=A2x=C5=93=C2=B1=C3=8A&=C3=BC=C3'=C2=AF=C5-=06=C2=AD =C2=A2=C2=B0=1E=C2=AE=C2=81%y=C3=8Bk=B0=C3=82=C3=A2=C2=B2=C3=98m=C2=B6 =C5=B8=C3=C3=83=0C&j=C3=9A=C3=A8=C5=BE',r=B0=C25=C2=AB=C3=A2=C2=81 =C2=ABh=C2=AC=07=C2=AB I^r=C3=9A=C3=A2p=C2=B8=C2=AC=C2=B7=C3=B6=C5=92=014N4 =82=AC=99X@E9=15=0CI&=C2z =C3=9Ej=C3=97(=C5=BE=C3=97=C2=A7=C2=B5=C2 =A9l=C2=A1=C2=AB=C3=9A=C5-V=BA=A2=C3=AB=C3=A2j=C3=98^Y=C3=C3 =85=C2=A2=C2=BB=C2=C2=B1=C2=A8ky=C3=B8m=C2=B6=C5=B8=C3~=C5-=C3=AE=C5 =A1=C3=89=C5=A1=C2=B6=C2=BA'=B0=C3=8B=1C=C2=A2hm=C2=B6=C5=B8=C3~=C5 -=C3=AE=C5=A1=C3=89=C5=A1=C2=B6=C2=BA'=B0=C3=8B=1C=C2=A2o=C3=9A.+- =B0=C3=AD=C2=AE&=C3=AE=C2=B6*'Y=C3=C3=92=C5-=C3=97=9C =C2=A9=C3=A4=C3=8A=B9=C5=B8=C2=A2=C2=BC=C2=A8=C2=BA=C2=B8=1E=C2=9D=C3 =C3=A8=C2=BA=C3=8B.=C2=C5=A1+=C2=B4=C3=86=C2=AD=C2=B4:=C3=9A=93W =B9=C5-=C3=8B@vh=C2=A7j=1A=C3=9E~=1Bm=C2=A7=C3=C3=B0=C3=83 =C5 =A1=C2=B6=C2=BA'=B0=C3=8B=1C=C2=A2o=C3=9C=C2=A2{k=B0=C2=BB=C2=AD =C5-=B0=C3=A1=C2=B6=C3=9A=7F=C3=0C0=84=A2=C2=ABk=C2=A2x=C5=93=C2 =B1=C3=8A&=C3=BD=C3=8A'=C2=B6=C2=B8=BA=C2=BA=C3=98=C2=A8=C5=B8=C3=B6=C2 o=C3=B7=C3=A8=C5=BE=C3=9F=C3=A9=C2=AD=C3=AF=C3=9B=C2=A1=C3=9C=C2 -=C3=99=C2=A5 ________________________________ Message 5 _____________________________________ Time: 06:51:28 AM PST US Subject: AeroElectric-List: Re: Z14 question about adding in external power Piper style jack From: "user9253" Looking at figure Z-31B, Piper Style Ground Power Jack, there is no indication that the Ground PWR Contactor is energized. Once that contactor is energized during a jump start, it will hold through its contacts. If the pilot neglects to open the circuit breaker (or is not aware of the need), the ground PWR contactor coil will discharge the battery, similar to forgetting to shutting off the master. I suggest that an indicator light be connected across the contactor coil of the ground PWR contactor. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425270#425270 ________________________________ Message 6 _____________________________________ Time: 06:58:24 AM PST US Subject: AeroElectric-List: Re: LED Ghosting From: "donjohnston" Definite improvement! Probably usable. There's a small range where the MOSFET controlled LEDs go out before the others. But it's such a small range that I doubt it's an issue. Now I have to see if it's a doable mod to the PCB. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425273#425273 ________________________________ Message 7 _____________________________________ Time: 07:07:02 AM PST US Subject: Re: AeroElectric-List: Re: LED Ghosting From: Richard Girard Paul, IMHO the variance in brightness would be a distraction the pilot would not need to deal with when any of the warning LED's started lighting. Even if you know that brightness is not an issue the difference would draw the eye and the thinking away from the real problem. For that reason I would want uniform brightness, but as I said, it's just my opinion. Rick Girard do not archive On Thu, Jun 19, 2014 at 3:15 PM, Fisher Paul A. wrote: > FisherPaulA@johndeere.com> > > I'm confused by this thread. Back to the original issue - why is it > important that all of the LEDs in the annunciator panel have the same > brightness? Don't you just need to know if any particular one is on or > off? Aren't they used to indicate a problem? I would hope that during most > flights they would all be off. And if more than one of them was on, I > certainly wouldn't be worried about one being brighter or dimmer than > another - I'd be busy looking for a place to land! > > I do appreciate the electronics discussion about the physics of getting > them to the same brightness. I just don't understand why that is important > in this use case. > > Paul A. Fisher > RV7A N18PF > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com [mailto: > owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. > Nuckolls, III > Sent: Thursday, June 19, 2014 2:01 PM > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: Re: LED Ghosting > > --> > > At 12:47 PM 6/19/2014, you wrote: > > Resistors can make the oil pressure LED the same brightness as the others > under one set of conditions. But when the conditions change (reduced > dimmer voltage) the brightness of all LEDs will no longer be the same. > > > Quite true. Stings of led's driven in parallel from a common dimmer > will vistually track each other only when all the strings are > identical. From a pure physics perspective, LED light output is > proportional to the current in the device . . . for values at or > below the device's rated operating point. > > The only way for all LEDs to have the same brightness under all conditions > is if each circuit has the same components. A relay can be used to switch > the oil pressure LED to make that circuit the same as the other LEDs that > use mechanical contacts. Here are possible relays to use: > http://tinyurl.com/pt9yd6v or http://tinyurl.com/o3g77dc or > http://tinyurl.com/q28mku6 > > The quest for intensity tracking between the various > indicators is purely a matter of average current through the > devices. Suppose the annunciator panel featured in the > start of this thread had two LEDs in some slots, and > single LEDs in others. It's entirely possible that they > could be made to appear identical at some level of illumination > by juggling their series resistors . . . but a bit > of pencil whipping of the numbers will show that as > supply voltage is reduced, the current through a series > string of 2 LEDs will fall off faster than for a single > LED. > > The use of a relay to energize an LED string to > emulate the performance of an oil pressure > switch isn't the issue. For all practical > purposes, hard contacts and transistors produce > the same behavior when turned ON for any given > level of 'balanced' illumination. The variances > of configuration don't come into play until the > illumination is adjusted to some new value. > > This is why duty cycle switched dimming works so well > for mixed configurations of LED illumination. When you duty-cycle > switch the LED, peak light output remains constant while > the eye integrates a reduced average energy into a perceived > level of brightness that will be more uniform across mixed > configurations. > > I wrote the spec for a mix illumination dimmer control > for the Gates Piaggio GP-180 program where the design > goal was to dim 5v incandescent, 28v incandescent and > and 115vac electro-luminescent from a single knob. > > Nobody stood up and offered a proposal for that > spec (about 1985). With micro-controllers and lookup > table driven power supplies, it could be done today > but not easily back then. > > Joe is right, unless the constellation of illumination > sources have the same configuration, they will not > track each other well with simple adjustment of applied > voltage. > > > Bob . . . > > -- Zulu Delta Mk IIIC Thanks, Homer GBYM It isn't necessary to have relatives in Kansas City in order to be unhappy. - Groucho Marx ________________________________ Message 8 _____________________________________ Time: 07:28:14 AM PST US Subject: Re: AeroElectric-List: Re: LED Ghosting From: Eric Page Don, New diagram looked perfect. Glad to hear it works acceptably well. Hope you can bodge it into your PCB for a permanent solution! Eric On Jun 22, 2014, at 8:57 AM, "donjohnston" wrote: > Definite improvement! Probably usable. There's a small range where the MOSFET controlled LEDs go out before the others. But it's such a small range that I doubt it's an issue. > > Now I have to see if it's a doable mod to the PCB. do not archive ________________________________ Message 9 _____________________________________ Time: 08:07:01 AM PST US Subject: AeroElectric-List: Re: LED Ghosting From: "donjohnston" edpav8r(at)yahoo.com wrote: > Don, > > New diagram looked perfect. Glad to hear it works acceptably well. Hope you can bodge it into your PCB for a permanent solution! > > Eric Thanks. Looks like I may be able to mod the board (I wish it didn't cost so much to get these small one-off boards made :( ). I was worried that I was going to run into the same problem with the LR3C voltage regulator low voltage warning. But B&C apparently did it right. A 1.5K resistor across the LEDs eliminates the ghosting but doesn't dim the LEDs when on. WooHoo! :D -Don Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425280#425280 ________________________________ Message 10 ____________________________________ Time: 09:05:42 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: LED Ghosting Your voltage measurements confirmed that the annunciator output from your engine analyzer is decidedly not capable of driving an incandescent bulb . . . in fact, it appears that this particular output is not well thought out. Have you had any contact with the factory about this? What brand and model analyzer are we talking about. Are the installation manuals available on line? >Thanks. Looks like I may be able to mod the board (I wish it didn't >cost so much to get these small one-off boards made :( ). Emacs! This is the best alternative for 'buffering' the output port as it was handed to you. The size of the resistor still leaves some risk for 'ghosting'; there might be sufficient leakage in their output to produce a source-gate voltage that is greater than the threshold voltage on the FET . . . typically on the order of 2-3 volts. A resistor on the order of 470 ohms is suggested. >I was worried that I was going to run into the same problem with the >LR3C voltage regulator low voltage warning. But B&C apparently did >it right. A 1.5K resistor across the LEDs eliminates the ghosting >but doesn't dim the LEDs when on. WooHoo! :D That incandescent lamp driver was designed by yours truly about 30 years ago for some devices being offered to Cessna and Beech . . . it got folded into the B&C products when I did their early designs. But nobody was driving LEDs back then. Turn-off resistors had to be added to accomodate the conversion. The FET buffer is the obvious 'fix' in this instance but should not have been necessary. Bob . . . ________________________________ Message 11 ____________________________________ Time: 09:14:43 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: LED Ghosting At 08:57 AM 6/22/2014, you wrote: > >Definite improvement! Probably usable. There's a small range where >the MOSFET controlled LEDs go out before the others. The Perhelion dimmer is linear as opposed to duty-cycle switched so yes, at some lower voltage, the gate-turn-on voltage for the FET becomes a significant part of the supply voltage out of the dimmer and LEDs controlled by the FET will go out first. A refinement of the design could consider duty-cycle switched dimming or going to logic-level gate FET with a much lower threshold voltage. This has been an excellent study in the relative chaos that can arise from poorly tested products. We were recently discussing how poorly designed tachometer circuits for sampling ignition signals can add risk affecting engine performance. This "ghosting" problem is a case where less than passing grades on a manufacturer's homework caused a lot of unnecessary work-arounds that are STILL less than ideal. Bob . . . ________________________________ Message 12 ____________________________________ Time: 12:09:19 PM PST US Subject: AeroElectric-List: Re: LED Ghosting From: "donjohnston" nuckolls.bob(at)aeroelect wrote: > Your voltage measurements confirmed that the annunciator > output from your engine analyzer is decidedly not capable > of driving an incandescent bulb . . . in fact, it appears > that this particular output is not well thought out. Have > you had any contact with the factory about this? What > brand and model analyzer are we talking about. Are the > installation manuals available on line? But... It does work with an incandescent bulb... As long as it's wired to 12v and not a dimmer. The Engine Analyzer is a Grand Rapids EIS 6000. Doc's are here: http://grtavionics.com/manualseis.html Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425291#425291 ________________________________ Message 13 ____________________________________ Time: 03:13:20 PM PST US From: "Jeffrey W. Skiba" Subject: RE: AeroElectric-List: How to decide if a heat sink is required for a Rect Bridge SW4gYWRkaXRpb24gdG8gdGhlIGJlbG93OiBob3cgZG8geW91IGtub3cgaWYgeW91IGhhdmUgdG8g aGF2ZSBhIOKAnGhlYXQgc2luaw0KSW5zdWxhdG9y4oCdICAgPz8/IERvIHdlIGhhdmUgdG8gd2l0 aCB0aGlzIHR5cGUgb2YgaW5zdGFsbGF0aW9uID8NCg0KSSBvcmlnaW5hbGx5IHdhcyBnb2luZyB0 byBtb3VudCBlYWNoIG9uZSBvbiBpdOKAmXMgb3duIGhlYXQgc2luayBidXQgbm93IEkgYW0gdGhp bmtpbmcgYWxsIHRocmVlIG9uIHRoZSBzYW1lIGhlYXQgc2luaywgYW0gSSBhc2tpbmcgZm9yIGVs ZWN0cmljYWwgc3BhcmtzID8/DQoNCg0KDQpTdWJqZWN0OiBBZXJvRWxlY3RyaWMtTGlzdDogSG93 IHRvIGRlY2lkZSBpZiBhIGhlYXQgc2luayBpcyByZXF1aXJlZCBmb3IgYSBSZWN0IEJyaWRnZQ0K DQoNCk9rYXkgSSBoYXZlIHRoZXNlIFJlY3QgQnJpZGdlDQoNCkdCUEMgU2VyaWVzPGh0dHA6Ly93 d3cudmlzaGF5LmNvbS9kb2M/OTM1NzU+DQoNCkRpZ2lrZXkgZ2JwYzM1MDJhDQoNCg0KDQozNSBh bXAgdmVyc2lvbg0KDQoNCg0KDQoNCkkgcGxhbiBvbiB1c2luZyB0aGVtIHRvIGNvbm5lY3QgYSBk ZXZpY2UgZnJvbSB0d28gZGlmZmVyZW50IGRjIGJhdHRlcmllcw0KDQpUbyBydW4gYSBsb2FkIG9m IGFib3V0IDYgYW1wcyBjb250aW51b3VzDQoNClRoaXMgaXMgYSBjb21wb3NpdGUgYWlyZnJhbWUg c28gbm8gcGxhY2UgdG8gYm9sdCBkaXJlY3RseSB0byBtZXRhbA0KDQoNCg0KMSkgICAgICBJcyBh IGhlYXQgc2luayByZXF1aXJlZCA/DQoNCjIpICAgICAgV291bGQgaXQgYmUgYSBnb29kIGlkZWEg aWYgb25lIGlzIG5vdCByZXF1aXJlZA0KDQozKSAgICAgIEhvdyBkbyB3ZSB0ZWxsIGhvdyBiaWcg b2YgYSBoZWF0IHNpbmsgd2UgbmVlZCA/DQoNCg0KDQoNCg0KV291bGQgYSBkaWdpa2V5IHBhcnQg bnVtYmVyIGhzMTE0ICB3b3JrIHByb3Blcmx5ID8NCg0KSG93IGNhbiB3ZSB0ZWxsID8NCg0KDQoN ClRoYW5rcw0KDQpKZWZmLg0K ________________________________ Message 14 ____________________________________ Time: 03:43:40 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: LED Ghosting At 02:08 PM 6/22/2014, you wrote: > > >nuckolls.bob(at)aeroelect wrote: > > Your voltage measurements confirmed that the annunciator > > output from your engine analyzer is decidedly not capable > > of driving an incandescent bulb . . . in fact, it appears > > that this particular output is not well thought out. Have > > you had any contact with the factory about this? What > > brand and model analyzer are we talking about. Are the > > installation manuals available on line? > > >But... It does work with an incandescent bulb... As long as it's >wired to 12v and not a dimmer. ??? What size of bulb . . . how many milliamps does the bulb draw? The voltages you observed in circuit 2 say that with JUST the two LEDS and their companion resistor attached to the engine analyzer, all measured voltage drops add up to the supply voltage. This means that for that current level, the engine analyzer will pull the lamp port nearly to ground. I believe the resistor was 390 ohms . . . so load on the engine analyzer in case #1 was 8.07/390 = 20.6 milliamps. You added a resistor across the array in case #3 which says that voltage across the 390 ohm resistor dropped to 6.55 volts . . . so indeed, current through the lamps went down to 6.55/390 equals 7.2 millimaps . . . approximately 1/3 that of case #1. Further, you cite 10.7 volts across the 1K resistor for an additional 10.7 milliamps of load on the engine analyzer lamp port . . . for a total of 17.9 milliamps which is less than case #1. Yet you LOST some voltage in the engine analyzer. Total voltage drop in the lamps and resistor is 10.65 volts with a system voltage of 12.37 . . . or 1.72 volts went missing in the engine analyzer's lamp driver. In case #4 we see the same thing happening . . . with the disappearance of about 1.5 volts. The output switching device should not have that much loss . . . I would expect tens of millvolts tops. The voltages say yes, the LEDs are indeed biased up significantly lighter when the anti- ghosting resistor is added. But it's not clear why. >The Engine Analyzer is a Grand Rapids EIS 6000. >Doc's are here: >http://grtavionics.com/manualseis.html > Okay, the warning light output is described thusly: Emacs! The fact that it can 'shut down' automatically implies some kind of protective 'smarts' on this pin. At the same time, the rated switching current is more than adequate to the task of handling either LED or incandescent lamps . . . although the 'ghosting' phenomenon is not understood. Have you talked with GR about this? This still not making sense. Bob . . . ________________________________ Message 15 ____________________________________ Time: 04:49:39 PM PST US Subject: AeroElectric-List: Re: LED Ghosting From: "donjohnston" nuckolls.bob(at)aeroelect wrote: > ??? What size of bulb . . . how many milliamps does the bulb draw? > > The voltages you observed in circuit 2 say that with JUST the two LEDS and their companion resistor attached to the engine analyzer, all measured voltage drops add up to the supply voltage. This means that for that current level, the engine analyzer will pull the lamp port nearly to ground. I believe the resistor was 390 ohms . . . so load on the engine analyzer in case #1 was 8.07/390 = 20.6 milliamps. > > You added a resistor across the array in case #3 which says that voltage across the 390 ohm resistor dropped to 6.55 volts . . . so indeed, current through the lamps went down to 6.55/390 equals 7.2 millimaps . . . approximately 1/3 that of case #1. Further, you cite 10.7 volts across the 1K resistor for an additional 10.7 milliamps of load on the engine analyzer lamp port . . . for a total of 17.9 milliamps which is less than case #1. Yet you LOST some voltage in the engine analyzer. Total voltage drop in the lamps and resistor is 10.65 volts with a system voltage of 12.37 . . . or 1.72 volts went missing in the engine analyzer's lamp driver. In case #4 we see the same thing happening . . . with the disappearance of about 1.5 volts. > > The output switching device should not have that much loss . . . I would expect tens of millvolts tops. The voltages say yes, the LEDs are indeed biased up significantly lighter when the anti-ghosting resistor is added. But it's not clear why. > > Have you talked with GR about this? This still not making sense. > Bob . . . The bulb I used is a bulb that I got from B&C with the LR3C. I hooked it up just to see if it would behave properly (and it did). If you want, I can check the specs on it. I can't speak to or dispute the numbers or calculations that you present as that's not my area of expertise. I can only say with certainty what happens when the switch is thrown. I have spoken to GRT as I mentioned in the original post. They said the alarm output is designed for an incandescent bulb and that to make it work with an LED I would have to put a 1.5K resistor across the LED. Now I didn't explain complex (elaborate, convoluted, bizarre, whatever term you wish to use to describe my annunicator panel) nature of the warning light I had. Only that I was using an LED. They would have assumed that it was a single LED powered by a constant power source. I appreciate all the help and suggestions from everyone. I wish that this would have been a simple fix but it would seem that something is going on inside the engine analyzer that defies explanation. -Don Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425298#425298 ________________________________ Message 16 ____________________________________ Time: 06:48:03 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: How to decide if a heat sink is required for a Rect Bridge At 05:11 PM 6/22/2014, you wrote: In addition to the below: how do you know if you have to have a heat sink Insulator ??? Do we have to with this type of installation ? I originally was going to mount each one on its own heat sink but now I am thinking all three on the same heat sink, am I asking for electrical sparks ?? Why so many? Can you share a sketch of your application? Subject: AeroElectric-List: How to decide if a heat sink is required for a Rect Bridge Okay I have these Rect Bridge GBPC Series Digikey gbpc3502a 35 amp version At 6A continuous in these devices, no heat sinking is necessary I plan on using them to connect a device from two different dc batteries To run a load of about 6 amps continuous This is a composite airframe so no place to bolt directly to metal 1) Is a heat sink required ? 2) Would it be a good idea if one is not required 3) How do we tell how big of a heat sink we need ? Would a digikey part number hs114 work properly ? How can we tell ? If you were really pressing them to their electrical limits, there ARE thermal dissipation studies you can conduct to establish heat-sink sizing. Here is but one of many examples . . . http://tinyurl.com/lkly23x These devices were chosen decades ago for their mechanical conveniences in mounting and attaching wires. The fact that they were electrically ubber-robust wasn't a design goal . . . it just turned out that way. Unless they're mounted in a hot environment, they're good for 6A without additional sinking. Bob . . . ________________________________ Message 17 ____________________________________ Time: 06:49:28 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: LED Ghosting > >I appreciate all the help and suggestions from everyone. I wish that >this would have been a simple fix but it would seem that something >is going on inside the engine analyzer that defies explanation. Actually, it's very explainable . . . given all the facts. Can you give me a name/number at GRT? Bob . . . ________________________________ Message 18 ____________________________________ Time: 07:47:58 PM PST US Subject: AeroElectric-List: Re: LED Ghosting From: "donjohnston" Phone number for GRT is on their contact page. http://www.grtavionics.com/contact.html I don't recall who I spoke to about this. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=425304#425304 ________________________________ Message 19 ____________________________________ Time: 09:09:19 PM PST US From: "Jeffrey W. 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