---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 01/18/18: 17 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:43 AM - Re: diode on starter contactor (Alec Myers) 2. 07:38 AM - Re: diode on starter contactor (Eric Page) 3. 09:27 AM - Re: diode on starter contactor (Bernie Willis) 4. 09:50 AM - Re: diode on starter contactor (Alec Myers) 5. 09:58 AM - Re: diode on starter contactor (Bernie Willis) 6. 10:09 AM - Re: diode on starter contactor (Robert L. Nuckolls, III) 7. 10:13 AM - Re: diode on starter contactor (Robert L. Nuckolls, III) 8. 10:42 AM - Re: diode on starter contactor (Charlie England) 9. 12:17 PM - diode on starter contactor (Paul Millner) 10. 12:20 PM - Re: diode on starter contactor (Robert L. Nuckolls, III) 11. 01:40 PM - Re: diode on starter contactor (Eric Jones) 12. 01:56 PM - Re: diode on starter contactor (Alec Myers) 13. 01:56 PM - Re: diode on starter contactor (Ken Ryan) 14. 02:01 PM - Re: diode on starter contactor (Robert L. Nuckolls, III) 15. 02:39 PM - Re: diode on starter contactor (Alec Myers) 16. 04:50 PM - Re: diode on starter contactor (user9253) 17. 05:09 PM - Re: diode on starter contactor (Sebastien) ________________________________ Message 1 _____________________________________ Time: 05:43:06 AM PST US From: Alec Myers Subject: Re: AeroElectric-List: diode on starter contactor Inductors (a solenoid coil is a good example of a large inductor) resist sudden changes in current flowing through them. When you energize the solenoid the current through the coil grows slowly to its maximum value. When you break the circuit with the switch you are forcing a sudden change in current, which causes a massive voltage spike. In the microseconds after the switch contact breaks the gap at the switch contacts is narrow enough, and the voltage rise at the inductor is big enough, to cause arcing and contact damage in the switch. The diode allows the current in the coil to continue to flow after the switch contact is broken by completing the circuit from the ground terminal of the coil back to the now-disconnected other terminal. (A diagram should make this clearer). No sudden change in current means no sudden voltage rise and no possibility of arcing. The energy to drive the continuing current flow through the coil after the battery power has been removed from the solenoid terminal comes from the energy stored in the magnetic field. As the field collapses the current drops to zero. On Jan 18, 2018, at 1:59 AM, Bill Bear wrote: Bernie, As I understand it, when the solenoid is deenergized, a voltage surge peak passes through the circuit which ages the solenoid contacts. The diode prevents the passage of the surge current and lengthens the life of the solenoid contacts. The diode band end is connected to the positive side of the solenoid contractor and the other side of the diode is connected to ground at the solenoid. Bill > On Jan 17, 2018, at 20:49, Bernie wrote: > > Im trying to follow the diode and the starter sol. discussion. I missed the reason for the diode. > > Thanks > Bernie > > Sent from my iPhone > > On Jan 17, 2018, at 4:38 PM, Ken Ryan wrote: > >> Thanks everyone. >> >> >> On Wed, Jan 17, 2018 at 3:35 PM, Alec Myers wrote: >> Use the mounting bolt then, with a ring terminal under the bolt head. >> >> On Jan 17, 2018, at 19:18, Ken Ryan wrote: >> >>> Alec, like I said in my original post, there is no ground terminal. Ground is accomplished through the metal case. >>> >>> On Wed, Jan 17, 2018 at 3:10 PM, Alec Myers wrote: >>> >>> Wire it across the coil, so from non ground terminal to ground terminal, so its reverse polarized when the coil is energized. Then when power is removed, the magnetic field collapses driving current through the diode and avoiding a large back emf. >>> >>> If you put it the wrong way round, dont worry, it will just disappear. >>> >>> >>> >>> On Jan 17, 2018, at 18:56, Ken Ryan wrote: >>> >>> My starter contactor's coil gets its ground through the contactor's metal case. Given that, does it make any sense to use a diode? If so, how would that diode be implemented and how would it remain effective when the case itself is the ground path? >>> >>> Ken >>> >>> >>> ============ >>> - >>> Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List >>> ========== >>> FORUMS - >>> eferrer" target="_blank">http://forums.matronics.com >>> ========== >>> WIKI - >>> errer" target="_blank">http://wiki.matronics.com >>> ========== >>> b Site - >>> -Matt Dralle, List Admin. >>> rel="noreferrer" target="_blank">http://www.matronics.com/contribution >>> ========== >>> >>> >>> >>> >> ________________________________ Message 2 _____________________________________ Time: 07:38:34 AM PST US Subject: AeroElectric-List: Re: diode on starter contactor From: "Eric Page" Heres a really excellent video by a guy named Alan Wolke (an applications engineer at Tektronix) that explains back-EMF in inductive circuits and the function of snubber or flyback diodes. https://www.youtube.com/watch?v=c6I7Ycbv8B8 As you watch this, keep in mind that Alan is using a small signal relay with a relatively tiny coil that operates on a few tens of milliamps. Then consider the typical starter solenoid: it should be obvious that the potential (pardon the pun) for large voltage spikes is amplified by the physical size of its coil and large current that it consumes in operation. Eric Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477413#477413 ________________________________ Message 3 _____________________________________ Time: 09:27:39 AM PST US From: Bernie Willis Subject: Re: AeroElectric-List: diode on starter contactor I really appreciate the discussion on the theory. Also found this issue discussed in Aero Connection. I have an old Bonanza that occasionally produces a chattering sound when the master/battery switch in turned on. Now I suspect it is the master solenoid contacts showing signs of failure. A new solenoid is in order but the diode protection seems in order also. A little research shows diodes available in many voltage, capacitance and temperature rating, anything from .07 to $300. What are the parameters of an appropriate diode to protect a 12 volt master or starter solenoid? Bernie > On Jan 18, 2018, at 4:41 AM, Alec Myers wrote: > > > Inductors (a solenoid coil is a good example of a large inductor) resist sudden changes in current flowing through them. When you energize the solenoid the current through the coil grows slowly to its maximum value. When you break the circuit with the switch you are forcing a sudden change in current, which causes a massive voltage spike. In the microseconds after the switch contact breaks the gap at the switch contacts is narrow enough, and the voltage rise at the inductor is big enough, to cause arcing and contact damage in the switch. > > The diode allows the current in the coil to continue to flow after the switch contact is broken by completing the circuit from the ground terminal of the coil back to the now-disconnected other terminal. (A diagram should make this clearer). No sudden change in current means no sudden voltage rise and no possibility of arcing. > > The energy to drive the continuing current flow through the coil after the battery power has been removed from the solenoid terminal comes from the energy stored in the magnetic field. As the field collapses the current drops to zero. > > On Jan 18, 2018, at 1:59 AM, Bill Bear wrote: > > Bernie, > > As I understand it, when the solenoid is deenergized, a voltage surge peak passes through the circuit which ages the solenoid contacts. The diode prevents the passage of the surge current and lengthens the life of the solenoid contacts. The diode band end is connected to the positive side of the solenoid contractor and the other side of the diode is connected to ground at the solenoid. > > Bill > > >> On Jan 17, 2018, at 20:49, Bernie wrote: >> >> Im trying to follow the diode and the starter sol. discussion. I missed the reason for the diode. >> >> Thanks >> Bernie >> >> Sent from my iPhone >> >> On Jan 17, 2018, at 4:38 PM, Ken Ryan wrote: >> >>> Thanks everyone. >>> >>> >>> On Wed, Jan 17, 2018 at 3:35 PM, Alec Myers wrote: >>> Use the mounting bolt then, with a ring terminal under the bolt head. >>> >>> On Jan 17, 2018, at 19:18, Ken Ryan wrote: >>> >>>> Alec, like I said in my original post, there is no ground terminal. Ground is accomplished through the metal case. >>>> >>>> On Wed, Jan 17, 2018 at 3:10 PM, Alec Myers wrote: >>>> >>>> Wire it across the coil, so from non ground terminal to ground terminal, so its reverse polarized when the coil is energized. Then when power is removed, the magnetic field collapses driving current through the diode and avoiding a large back emf. >>>> >>>> If you put it the wrong way round, dont worry, it will just disappear. >>>> >>>> >>>> >>>> On Jan 17, 2018, at 18:56, Ken Ryan wrote: >>>> >>>> My starter contactor's coil gets its ground through the contactor's metal case. Given that, does it make any sense to use a diode? If so, how would that diode be implemented and how would it remain effective when the case itself is the ground path? >>>> >>>> Ken >>>> >>>> >>>> ============ >>>> - >>>> Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List >>>> ========== >>>> FORUMS - >>>> eferrer" target="_blank">http://forums.matronics.com >>>> ========== >>>> WIKI - >>>> errer" target="_blank">http://wiki.matronics.com >>>> ========== >>>> b Site - >>>> -Matt Dralle, List Admin. >>>> rel="noreferrer" target="_blank">http://www.matronics.com/contribution >>>> ========== >>>> >>>> >>>> >>>> >>> > > > > > > ________________________________ Message 4 _____________________________________ Time: 09:50:46 AM PST US From: Alec Myers Subject: Re: AeroElectric-List: diode on starter contactor A ten cent 1N4001 is just fine. Voltage refers to a safe reverse voltage limit before avalanche breakdown: the coil diode is only reverse biased to 12V. A 1N4001 is rated to 50V. Current rating: somewhat irrelevant, since theres no sustained current load. A 1N4001 is good for up to 1A continuous, and 30A surge. Neither limit will be close to met in this application. Capacitance: refers to the junction capacitance when reverse biased. Irrelevant in this application. Physical package: anything big enough to solder easily will have enough thermal mass to absorb what little energy is stored in the coil magnetic field. On Jan 18, 2018, at 12:26 PM, Bernie Willis wrote: I really appreciate the discussion on the theory. Also found this issue discussed in Aero Connection. I have an old Bonanza that occasionally produces a chattering sound when the master/battery switch in turned on. Now I suspect it is the master solenoid contacts showing signs of failure. A new solenoid is in order but the diode protection seems in order also. A little research shows diodes available in many voltage, capacitance and temperature rating, anything from .07 to $300. What are the parameters of an appropriate diode to protect a 12 volt master or starter solenoid? Bernie > On Jan 18, 2018, at 4:41 AM, Alec Myers wrote: > > > Inductors (a solenoid coil is a good example of a large inductor) resist sudden changes in current flowing through them. When you energize the solenoid the current through the coil grows slowly to its maximum value. When you break the circuit with the switch you are forcing a sudden change in current, which causes a massive voltage spike. In the microseconds after the switch contact breaks the gap at the switch contacts is narrow enough, and the voltage rise at the inductor is big enough, to cause arcing and contact damage in the switch. > > The diode allows the current in the coil to continue to flow after the switch contact is broken by completing the circuit from the ground terminal of the coil back to the now-disconnected other terminal. (A diagram should make this clearer). No sudden change in current means no sudden voltage rise and no possibility of arcing. > > The energy to drive the continuing current flow through the coil after the battery power has been removed from the solenoid terminal comes from the energy stored in the magnetic field. As the field collapses the current drops to zero. > > On Jan 18, 2018, at 1:59 AM, Bill Bear wrote: > > Bernie, > > As I understand it, when the solenoid is deenergized, a voltage surge peak passes through the circuit which ages the solenoid contacts. The diode prevents the passage of the surge current and lengthens the life of the solenoid contacts. The diode band end is connected to the positive side of the solenoid contractor and the other side of the diode is connected to ground at the solenoid. > > Bill > > >> On Jan 17, 2018, at 20:49, Bernie wrote: >> >> Im trying to follow the diode and the starter sol. discussion. I missed the reason for the diode. >> >> Thanks >> Bernie >> >> Sent from my iPhone >> >> On Jan 17, 2018, at 4:38 PM, Ken Ryan wrote: >> >>> Thanks everyone. >>> >>> >>> On Wed, Jan 17, 2018 at 3:35 PM, Alec Myers wrote: >>> Use the mounting bolt then, with a ring terminal under the bolt head. >>> >>> On Jan 17, 2018, at 19:18, Ken Ryan wrote: >>> >>>> Alec, like I said in my original post, there is no ground terminal. Ground is accomplished through the metal case. >>>> >>>> On Wed, Jan 17, 2018 at 3:10 PM, Alec Myers wrote: >>>> >>>> Wire it across the coil, so from non ground terminal to ground terminal, so its reverse polarized when the coil is energized. Then when power is removed, the magnetic field collapses driving current through the diode and avoiding a large back emf. >>>> >>>> If you put it the wrong way round, dont worry, it will just disappear. >>>> >>>> >>>> >>>> On Jan 17, 2018, at 18:56, Ken Ryan wrote: >>>> >>>> My starter contactor's coil gets its ground through the contactor's metal case. Given that, does it make any sense to use a diode? If so, how would that diode be implemented and how would it remain effective when the case itself is the ground path? >>>> >>>> Ken >>>> >>>> >>>> ============ >>>> - >>>> Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List >>>> ========== >>>> FORUMS - >>>> eferrer" target="_blank">http://forums.matronics.com >>>> ========== >>>> WIKI - >>>> errer" target="_blank">http://wiki.matronics.com >>>> ========== >>>> b Site - >>>> -Matt Dralle, List Admin. >>>> rel="noreferrer" target="_blank">http://www.matronics.com/contribution >>>> ========== >>>> >>>> >>>> >>>> >>> > > > > > > ________________________________ Message 5 _____________________________________ Time: 09:58:26 AM PST US From: Bernie Willis Subject: Re: AeroElectric-List: diode on starter contactor Alec, That was a quick reply! Now I can proceed. Thanks, Bernie > On Jan 18, 2018, at 8:49 AM, Alec Myers wrote: > > > A ten cent 1N4001 is just fine. > > Voltage refers to a safe reverse voltage limit before avalanche breakdown: the coil diode is only reverse biased to 12V. A 1N4001 is rated to 50V. > Current rating: somewhat irrelevant, since theres no sustained current load. A 1N4001 is good for up to 1A continuous, and 30A surge. Neither limit will be close to met in this application. > Capacitance: refers to the junction capacitance when reverse biased. Irrelevant in this application. > Physical package: anything big enough to solder easily will have enough thermal mass to absorb what little energy is stored in the coil magnetic field. > > > > > > On Jan 18, 2018, at 12:26 PM, Bernie Willis wrote: > > > I really appreciate the discussion on the theory. Also found this issue discussed in Aero Connection. I have an old Bonanza that occasionally produces a chattering sound when the master/battery switch in turned on. Now I suspect it is the master solenoid contacts showing signs of failure. A new solenoid is in order but the diode protection seems in order also. A little research shows diodes available in many voltage, capacitance and temperature rating, anything from .07 to $300. What are the parameters of an appropriate diode to protect a 12 volt master or starter solenoid? > > Bernie > >> On Jan 18, 2018, at 4:41 AM, Alec Myers wrote: >> >> >> Inductors (a solenoid coil is a good example of a large inductor) resist sudden changes in current flowing through them. When you energize the solenoid the current through the coil grows slowly to its maximum value. When you break the circuit with the switch you are forcing a sudden change in current, which causes a massive voltage spike. In the microseconds after the switch contact breaks the gap at the switch contacts is narrow enough, and the voltage rise at the inductor is big enough, to cause arcing and contact damage in the switch. >> >> The diode allows the current in the coil to continue to flow after the switch contact is broken by completing the circuit from the ground terminal of the coil back to the now-disconnected other terminal. (A diagram should make this clearer). No sudden change in current means no sudden voltage rise and no possibility of arcing. >> >> The energy to drive the continuing current flow through the coil after the battery power has been removed from the solenoid terminal comes from the energy stored in the magnetic field. As the field collapses the current drops to zero. >> >> On Jan 18, 2018, at 1:59 AM, Bill Bear wrote: >> >> Bernie, >> >> As I understand it, when the solenoid is deenergized, a voltage surge peak passes through the circuit which ages the solenoid contacts. The diode prevents the passage of the surge current and lengthens the life of the solenoid contacts. The diode band end is connected to the positive side of the solenoid contractor and the other side of the diode is connected to ground at the solenoid. >> >> Bill >> >> >>> On Jan 17, 2018, at 20:49, Bernie wrote: >>> >>> Im trying to follow the diode and the starter sol. discussion. I missed the reason for the diode. >>> >>> Thanks >>> Bernie >>> >>> Sent from my iPhone >>> >>> On Jan 17, 2018, at 4:38 PM, Ken Ryan wrote: >>> >>>> Thanks everyone. >>>> >>>> >>>> On Wed, Jan 17, 2018 at 3:35 PM, Alec Myers wrote: >>>> Use the mounting bolt then, with a ring terminal under the bolt head. >>>> >>>> On Jan 17, 2018, at 19:18, Ken Ryan wrote: >>>> >>>>> Alec, like I said in my original post, there is no ground terminal. Ground is accomplished through the metal case. >>>>> >>>>> On Wed, Jan 17, 2018 at 3:10 PM, Alec Myers wrote: >>>>> >>>>> Wire it across the coil, so from non ground terminal to ground terminal, so its reverse polarized when the coil is energized. Then when power is removed, the magnetic field collapses driving current through the diode and avoiding a large back emf. >>>>> >>>>> If you put it the wrong way round, dont worry, it will just disappear. >>>>> >>>>> >>>>> >>>>> On Jan 17, 2018, at 18:56, Ken Ryan wrote: >>>>> >>>>> My starter contactor's coil gets its ground through the contactor's metal case. Given that, does it make any sense to use a diode? If so, how would that diode be implemented and how would it remain effective when the case itself is the ground path? >>>>> >>>>> Ken >>>>> >>>>> >>>>> ============ >>>>> - >>>>> Electric-List" rel="noreferrer" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List >>>>> ========== >>>>> FORUMS - >>>>> eferrer" target="_blank">http://forums.matronics.com >>>>> ========== >>>>> WIKI - >>>>> errer" target="_blank">http://wiki.matronics.com >>>>> ========== >>>>> b Site - >>>>> -Matt Dralle, List Admin. >>>>> rel="noreferrer" target="_blank">http://www.matronics.com/contribution >>>>> ========== >>>>> >>>>> >>>>> >>>>> >>>> >> >> >> >> >> >> > > > > > > > > > > ________________________________ Message 6 _____________________________________ Time: 10:09:37 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: diode on starter contactor At 11:49 PM 1/17/2018, you wrote: >I=99m trying to follow the diode and the starter >sol. discussion. I missed the reason for the diode. We've had several discussions on spike-suppression diodes on relays and contactors over the years. One of the first was prompted by a snafu over an airworthiness directive against the ACS/Gerdes off-left-right-on-start key switches. Seems the inductive spike fire generated by relatively high coil current of some starter contactors was eating up the start contact in the key switch. Here's one example of a OEM aircafter's response to the AD. https://goo.gl/1XvDtj This was the CORRECT way to install the diode . . . the AD also called for refurbishment of the start switch contacts within the keyswitch. Here's background on the physics for proper placement of the diode. https://goo.gl/WUS1Ya The problem would get potentially worse when lightweight starters started showing up. Still more stress on the switch was a function of a two-stage engagement scenario which impressed a much larger engagement inrush current compared to legacy starter contactors. Here's the background. https://goo.gl/opeqsM Later in the discussions, there was consternation about how 'inadvised' configuration of spike suppression would cause the contactor's points to open more slowly and exacerbate contact wear. The assertion was predicated on an article published by Potter-Brumfield https://goo.gl/iCrqch The author asserts that a diode connected right across the contactor/relay coil results in significantly slower contact opening velocity. This prompted a trip to the workbench to explore the physics: https://goo.gl/KNTr8y For our purposes, the diode was demonstrated to effect a DELAY in contact first opening . . . but once the contacts started to move, the AIR GAP in the magnetic circuit had a much more profound effect on opening velocity than did the slower decay of current in the contactor coil. The short answer is that adding a plain-jane diode across the coil of any relay or contactor in the airplane will not noticeably affect service life of that device. The diode improves service life of the SWITCH THAT CONTROLS THE CONTACTOR. Further, contactor coils do not propagate spikes onto the system looking for vulnerable solid state electronics to fry. Bob . . . ________________________________ Message 7 _____________________________________ Time: 10:13:37 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: diode on starter contactor At 11:49 AM 1/18/2018, you wrote: > >A ten cent 1N4001 is just fine. > >Voltage refers to a safe reverse voltage limit >before avalanche breakdown: the coil diode is >only reverse biased to 12V. A 1N4001 is rated to 50V. >Current rating: somewhat irrelevant, since >there=99s no sustained current load. A 1N4001 is >good for up to 1A continuous, and 30A surge. >Neither limit will be close to met in this application. Absolutely correct. My personal favorites are the 1N5400 series devices, NOT for their electrical ratings but for mechanical robustness. Example: https://goo.gl/2CGXgf Bob . . . ________________________________ Message 8 _____________________________________ Time: 10:42:08 AM PST US Subject: Re: AeroElectric-List: diode on starter contactor From: Charlie England On 1/18/2018 12:13 PM, Robert L. Nuckolls, III wrote: > At 11:49 AM 1/18/2018, you wrote: >> >> A ten cent 1N4001 is just fine. >> >> Voltage refers to a safe reverse voltage limit before avalanche >> breakdown: the coil diode is only reverse biased to 12V. A 1N4001 is >> rated to 50V. >> Current rating: somewhat irrelevant, since theres no sustained >> current load. A 1N4001 is good for up to 1A continuous, and 30A >> surge. Neither limit will be close to met in this application. > > Absolutely correct. My personal favorites > are the 1N5400 series devices, NOT for their > electrical ratings but for mechanical > robustness. Example: > > https://goo.gl/2CGXgf > > > Bob . . . > And, while I haven't priced the 5400 series, the 4000 series prices used to be virtually identical from 4001 to 4007 (1KV rating). Not that you'd need it for this application, but when I repaired electrons for a living, we just stocked the 07s because they work for everything at that current rating. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 9 _____________________________________ Time: 12:17:46 PM PST US Subject: AeroElectric-List: diode on starter contactor From: Paul Millner >> when the solenoid is de-energized, a voltage surge peak passes through the circuit which ages the solenoid contacts. The diode prevents the passage of the surge current and lengthens the life of the solenoid contacts. For an abundance of clarity, the diode across the coil terminals does NOT protect the solenoid's contacts. It protects instead the switch contacts of whatever switch controls that solenoid coil: the starter switch for the starter contactor; the master switch contacts for the master contactor. Paul ________________________________ Message 10 ____________________________________ Time: 12:20:12 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: diode on starter contactor >> Bob . . . >And, while I haven't priced the 5400 series, the 4000 series prices >used to be virtually identical from 4001 to 4007 (1KV rating). Not >that you'd need it for this application, but when I repaired >electrons for a living, we just stocked the 07s because they work >for everything at that current rating. Astute observation. I've not confirmed this with a real diode-maker person but . . . I was working at a nuclear fuels manufacturing company in Apollo, PA where a colleague asserted that variously rated diodes were all made on the same line. They were screened for breakdown voltage looking first for devices that would function as 1000 volt devices. When the order for 007 parts was 'filled', the next screen was for the lower voltage part with the lowest breakdown would be marked 000. Over the years, production variability went down to the point where virtually all parts would make the cut for 1kV parts. But rather than upset the legacy apple-cart, they continued to market the lower voltage part numbers . . . which were in fact 1 kV devices. Somewhere around here I've got a 2 kV power supply. It would be interesting to see just how far one can push the modern LV parts . . . but that ain't happ'ng soon . . . Bob . . . ________________________________ Message 11 ____________________________________ Time: 01:40:07 PM PST US Subject: Re: AeroElectric-List: diode on starter contactor From: Eric Jones This subject has been discussed here for years. My opinion and what I have suggested for years is that the current best practice is to use bidirectional zener diodes. Regular diodes are problematic. See attached. You can use what I suggest or slightly heavier ones for better mechanical properties. (I am currently shipping the 5KE20CA parts). Eric M. Jones -Bought a 177RG Cardinal. ________________________________ Message 12 ____________________________________ Time: 01:56:37 PM PST US From: Alec Myers Subject: Re: AeroElectric-List: diode on starter contactor Eric, I see great marketing (FUD) in that document but no actual information. What do you believe to be the problem with a regular diode? On Jan 18, 2018, at 4:38 PM, Eric Jones wrote: This subject has been discussed here for years. My opinion and what I have suggested for years is that the current best practice is to use bidirectional zener diodes. Regular diodes are problematic. See attached. You can use what I suggest or slightly heavier ones for better mechanical properties. (I am currently shipping the 5KE20CA parts). Eric M. Jones -Bought a 177RG Cardinal. ________________________________ Message 13 ____________________________________ Time: 01:56:42 PM PST US From: Ken Ryan Subject: Re: AeroElectric-List: diode on starter contactor Eric, is it okay to solder a wire to your snapjacks? On Thu, Jan 18, 2018 at 12:38 PM, Eric Jones wrote: > This subject has been discussed here for years. > > My opinion and what I have suggested for years is that the current best > practice is to use bidirectional zener diodes. Regular diodes are > problematic. See attached. > > You can use what I suggest or slightly heavier ones for better mechanical > properties. (I am currently shipping the 5KE20CA parts). > > Eric M. Jones > > -Bought a 177RG Cardinal. > > ________________________________ Message 14 ____________________________________ Time: 02:01:40 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: diode on starter contactor At 03:38 PM 1/18/2018, you wrote: >This subject has been discussed here for years. > >My opinion and what I have suggested for years is that the current >best practice is to use bidirectional zener diodes. Regular diodes >are problematic. See attached. Emacs! Can you demonstrate this? "Excessive" is non-quantified. Was my bench top study flawed in some way? Bob . . . ________________________________ Message 15 ____________________________________ Time: 02:39:40 PM PST US From: Alec Myers Subject: Re: AeroElectric-List: diode on starter contactor Im trying to work out why a diode has *any* significant effect on release time compared to a tranzorb or similar, and if it did, why you might care. Also, why should it have any effect on relay life reduction ? My skeptical self needs help to get beyond merely more expensive therefore must be better. On Jan 18, 2018, at 5:01 PM, Robert L. Nuckolls, III wrote: At 03:38 PM 1/18/2018, you wrote: > This subject has been discussed here for years. > > My opinion and what I have suggested for years is that the current best practice is to use bidirectional zener diodes. Regular diodes are problematic. See attached. Can you demonstrate this? "Excessive" is non-quantified. Was my bench top study flawed in some way? Bob . . . ________________________________ Message 16 ____________________________________ Time: 04:50:50 PM PST US Subject: AeroElectric-List: Re: diode on starter contactor From: "user9253" A capacitor opposes any change in voltage. An inductor (coil) opposes any change in current. When the switch is closed (Figure 1), positive current flows from left to right through the coil. The diode does not conduct because positive current can not flow against the arrow. _ When the switch is opened (Figure 2), the coil opposes any change and tries to maintain the current. The coil is no longer a load. The coil is now a source, like a battery. Induced current still flows in the same direction through the coil from left to right. But the polarity has changed because because the coil is now a source, not a load. The diode now conducts because positive on the right side flows with the arrow. Current always tries to return to the source, the coil in this case. It takes the path of least resistance, which is through the diode, not across the open switch contacts. The induced voltage is limited to the forward voltage drop across the diode. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477433#477433 Attachments: http://forums.matronics.com//files/inductor__213.jpg ________________________________ Message 17 ____________________________________ Time: 05:09:37 PM PST US From: Sebastien Subject: Re: AeroElectric-List: diode on starter contactor Last year I put a lighter AGM battery in my aircraft and moved it to the firewall along with the master contactor and made some new diodes for the contactors (one was broken). Saved about 4 pounds in wiring alone! Only problem afterwards was that if the battery was even slightly down sometimes the starter would turn a split second and then nothing. Repeated attempts usually ended up with the starter eventually running fine until the engine started. Putting a voltmeter on the starter confirmed that the problem was a lack of power to the starter, not the starter itself. I had a battery problem later on and replaced the battery, no change. Thinking I had messed up the starter contactor while tightening nuts on it I swapped it out, no change. At this point I started to suspect my diode so I disconnected it: Problem gone! I suspect I installed it backwards. Going to make the new one with clear shrinkwrap tubing so it can't happen again. On Thu, Jan 18, 2018 at 2:37 PM, Alec Myers wrote: > > I=99m trying to work out why a diode has *any* significant effect o n release > time compared to a tranzorb or similar, and if it did, why you might care .. > Also, why should it have any effect on relay life reduction ? > > My skeptical self needs help to get beyond merely =9Cmore expensive > therefore must be better=9D. > > > On Jan 18, 2018, at 5:01 PM, Robert L. Nuckolls, III < > nuckolls.bob@aeroelectric.com> wrote: > > At 03:38 PM 1/18/2018, you wrote: > > This subject has been discussed here for years. > > > > My opinion and what I have suggested for years is that the current best > practice is to use bidirectional zener diodes. Regular diodes are > problematic. See attached. > > > > Can you demonstrate this? "Excessive" is non-quantified. > Was my bench top study flawed in some way? > > > Bob . . . > > =========== =========== =========== =========== =========== > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.