---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 05/21/08: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:46 AM - Coil Suppression Techniques. (Eric M. Jones) 2. 12:50 PM - Re: Coil Suppression Techniques. (sam@fr8dog.net) 3. 02:24 PM - Re: Coil Suppression Techniques (John Cleary) 4. 02:37 PM - Re: Coil Suppression Techniques. () 5. 03:51 PM - Re: Coil Suppression Techniques. (Robert L. Nuckolls, III) 6. 04:53 PM - Re: Coil Suppression Techniques (With Corrected Link) (Robert L. Nuckolls, III) 7. 05:05 PM - Re: Coil Suppression Techniques. (Eric M. Jones) 8. 10:31 PM - Re: Re: Coil Suppression Techniques. (sam@fr8dog.net) ________________________________ Message 1 _____________________________________ Time: 07:46:35 AM PST US Subject: AeroElectric-List: Coil Suppression Techniques. From: "Eric M. Jones" I have this weird Deja Vu feeling that we have covered this subject before. And I will save you the trouble Bob....I know you'll never agree, and you'll retort with a long quasi-techno piece and then stumble TO EXACTLY THE WRONG CONCLUSION. Coil suppression and relay contact arcing have been well studied: See: http://relays.tycoelectronics.com/appnotes/ Basically (ESPECIALLY with contactors) Do not use diodes for coil suppression unless you're hoping for greatly reduced relay/contactor life, so you can get stuck in a remote area and have an adventure. I know people like this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit! Here's what sane people have figured out: Mechanical relays and contactors depend upon magnetism generated by an electric current running through a wire coil. When the current stops, the magnetic field collapses. But the relay does not know the difference between a wire coil moving in a magnetic field (as in a generator) or a magnetic field moving in a wire coil (as in a collapsing magnetic field). Thus a large voltage1000V to 1500V typicallyis induced in the coil. This current goes the same direction the original current didso it slows the contact openingallowing arcing, chatter, bouncing, contact welding and even re-closure! Yikes! The common palliative is a diode AND zener in series, or better yet, a bidirectional zener across the coil. They call these Transils, Surmetics, Transorbs, TranZorbs, TransGuards, Mosorbs; the list is endless. (Over-paid executives dream up these names.) They are generic P6KE18CA bidirectional zeners. Jeeeeeze........ -------- 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=184184#184184 Attachments: http://forums.matronics.com//files/snapjack_101.pdf http://forums.matronics.com//files/snapjack_182.pdf ________________________________ Message 2 _____________________________________ Time: 12:50:34 PM PST US From: "sam@fr8dog.net" Subject: Re: AeroElectric-List: Coil Suppression Techniques. So Eric, do I just order a P6KE18CA, from Radio Shack, or do I need a specific Voltage rating for my relays on my 12v homebuilt? Sam ---- "Eric M. Jones" wrote: ============ I have this weird Deja Vu feeling that we have covered this subject before. And I will save you the trouble Bob....I know you'll never agree, and you'll retort with a long quasi-techno piece and then stumble TO EXACTLY THE WRONG CONCLUSION. Coil suppression and relay contact arcing have been well studied: See: http://relays.tycoelectronics.com/appnotes/ Basically (ESPECIALLY with contactors) Do not use diodes for coil suppression unless you're hoping for greatly reduced relay/contactor life, so you can get stuck in a remote area and have an adventure. I know people like this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit! Here's what sane people have figured out: Mechanical relays and contactors depend upon magnetism generated by an electric current running through a wire coil. When the current stops, the magnetic field collapses. But the relay does not know the difference between a wire coil moving in a magnetic field (as in a generator) or a magnetic field moving in a wire coil (as in a collapsing magnetic field). Thus a large voltage1000V to 1500V typicallyis induced in the coil. This current goes the same direction the original current didso it slows the contact openingallowing arcing, chatter, bouncing, contact welding and even re-closure! Yikes! The common palliative is a diode AND zener in series, or better yet, a bidirectional zener across the coil. They call these Transils, Surmetics, Transorbs, TranZorbs, TransGuards, Mosorbs; the list is endless. (Over-paid executives dream up these names.) They are generic P6KE18CA bidirectional zeners. Jeeeeeze........ -------- 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=184184#184184 Attachments: http://forums.matronics.com//files/snapjack_101.pdf http://forums.matronics.com//files/snapjack_182.pdf ________________________________ Message 3 _____________________________________ Time: 02:24:57 PM PST US From: "John Cleary" Subject: RE: AeroElectric-List: Coil Suppression Techniques Eric, Thank you for this contribution. I am planning to use a relay to switch power to my avionics/endurance busses. Normal loads at switch on/turn off would be in the order of 10 amps at 12 volts. What relay would you recommend and would you draw a simple diagram for a non electrical person showing how and where to wire the P6KE18CA bidirectional zener? Thanks once again, John -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of sam@fr8dog.net Sent: Thursday, 22 May 2008 5:43 AM Subject: Re: AeroElectric-List: Coil Suppression Techniques - use generic P6KE18CA bidirectional zener So Eric, do I just order a P6KE18CA, from Radio Shack, or do I need a specific Voltage rating for my relays on my 12v homebuilt? Sam ---- "Eric M. Jones" wrote: ============ I have this weird Deja Vu feeling that we have covered this subject before. And I will save you the trouble Bob....I know you'll never agree, and you'll retort with a long quasi-techno piece and then stumble TO EXACTLY THE WRONG CONCLUSION. Coil suppression and relay contact arcing have been well studied: See: http://relays.tycoelectronics.com/appnotes/ Basically (ESPECIALLY with contactors) Do not use diodes for coil suppression unless you're hoping for greatly reduced relay/contactor life, so you can get stuck in a remote area and have an adventure. I know people like this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit! Here's what sane people have figured out: Mechanical relays and contactors depend upon magnetism generated by an electric current running through a wire coil. When the current stops, the magnetic field collapses. But the relay does not know the difference between a wire coil moving in a magnetic field (as in a generator) or a magnetic field moving in a wire coil (as in a collapsing magnetic field). Thus a large voltage1000V to 1500V typicallyis induced in the coil. This current goes the same direction the original current didso it slows the contact openingallowing arcing, chatter, bouncing, contact welding and even re-closure! Yikes! The common palliative is a diode AND zener in series, or better yet, a bidirectional zener across the coil. They call these Transils, Surmetics, Transorbs, TranZorbs, TransGuards, Mosorbs; the list is endless. (Over-paid executives dream up these names.) They are generic P6KE18CA bidirectional zeners. Jeeeeeze........ -------- 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=184184#184184 Attachments: http://forums.matronics.com//files/snapjack_101.pdf http://forums.matronics.com//files/snapjack_182.pdf Checked by AVG. Checked by AVG. ________________________________ Message 4 _____________________________________ Time: 02:37:03 PM PST US Subject: RE: AeroElectric-List: Coil Suppression Techniques. From: So are we saying that people who market and sell relays bragging about 240,000 life clicks are full of mumbo jumbo? I know Radio Shack is. Should we buy a 40A relay to run a 30 A load and prolong the life of the switch? Jeeze, they're only a $1 more. Are we worried about something that will only be used for the life of the airplane? Ok, in reality I only turn the headlight on say, 100 times / year. That's probably 30 times more than average. At that rate I'll be long dead before I achieve 240k clicks. Radio Shack sells a lot of diodes to people who assume they provide feedback suppression. My BMW has an awful lot of Bosch relays that have never worn out. What are they doing to ensure long life? I crank up the headlights, horn etc in my car 10 X more than anything I do in the airplane. At $6 a piece I can carry a few into the backwoods. -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of sam@fr8dog.net Sent: Wednesday, May 21, 2008 3:43 PM Subject: Re: AeroElectric-List: Coil Suppression Techniques. --> So Eric, do I just order a P6KE18CA, from Radio Shack, or do I need a specific Voltage rating for my relays on my 12v homebuilt? Sam ---- "Eric M. Jones" wrote: ============ --> I have this weird Deja Vu feeling that we have covered this subject before. And I will save you the trouble Bob....I know you'll never agree, and you'll retort with a long quasi-techno piece and then stumble TO EXACTLY THE WRONG CONCLUSION. Coil suppression and relay contact arcing have been well studied: See: http://relays.tycoelectronics.com/appnotes/ Basically (ESPECIALLY with contactors) Do not use diodes for coil suppression unless you're hoping for greatly reduced relay/contactor life, so you can get stuck in a remote area and have an adventure. I know people like this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit! Here's what sane people have figured out: Mechanical relays and contactors depend upon magnetism generated by an electric current running through a wire coil. When the current stops, the magnetic field collapses. But the relay does not know the difference between a wire coil moving in a magnetic field (as in a generator) or a magnetic field moving in a wire coil (as in a collapsing magnetic field). Thus a large voltage1000V to 1500V typicallyis induced in the coil. This current goes the same direction the original current didso it slows the contact openingallowing arcing, chatter, bouncing, contact welding and even re-closure! Yikes! The common palliative is a diode AND zener in series, or better yet, a bidirectional zener across the coil. They call these Transils, Surmetics, Transorbs, TranZorbs, TransGuards, Mosorbs; the list is endless. (Over-paid executives dream up these names.) They are generic P6KE18CA bidirectional zeners. Jeeeeeze........ -------- 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=184184#184184 Attachments: http://forums.matronics.com//files/snapjack_101.pdf http://forums.matronics.com//files/snapjack_182.pdf ________________________________ Message 5 _____________________________________ Time: 03:51:31 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Coil Suppression Techniques. At 07:42 AM 5/21/2008 -0700, you wrote: > >I have this weird Deja Vu feeling that we have covered this subject >before. And I will save you the trouble Bob....I know you'll never agree, >and you'll retort with a long quasi-techno piece and then stumble TO >EXACTLY THE WRONG CONCLUSION. > >Coil suppression and relay contact arcing have been well studied: See: >http://relays.tycoelectronics.com/appnotes/ > >Basically (ESPECIALLY with contactors) Do not use diodes for coil >suppression unless you're hoping for greatly reduced relay/contactor life, >so you can get stuck in a remote area and have an adventure. I know people >like this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit! You've cited that document before. And I've read it several times both before you cited it and after you cited it. Kindly point out to me where the authors offer DATA supporting an assertion that the plain vanilla diode coil suppression has a profound effect on relay life. They correctly asserted and I confirmed that diodes do indeed extend the time from switch opening until energized contacts begin to move. This is opening delay. They went on to extrapolate that opening delay translates directly into slower contact spreading velocity and extrapolated further that this translated to increased contact wear. I did the experiments and published the results that argue against their extrapolations. If you have some data to the contrary, please share it with us. Just because you've read some words under the letter head and over the signatures of persons in high places does not make their words golden unless they're supported by data from and understanding of repeatable experiments. >Here's what sane people have figured out: . . . are you suggesting I am less than sane?? >Mechanical relays and contactors depend upon magnetism generated by an >electric current running through a wire coil. When the current stops, the >magnetic field collapses. But the relay does not know the difference >between a wire coil moving in a magnetic field (as in a generator) or a >magnetic field moving in a wire coil (as in a collapsing magnetic field). >Thus a large voltage1000V to 1500V typicallyis induced in the coil. >This current goes the same direction the original current didso it >slows the contact openingallowing arcing, chatter, bouncing, contact >welding and even re-closure! Yikes! Go to your workbench, measure it, document it and share it with us. Show me where my data and interpretation of my data is wrong. The important feature of relay and contactor operation that you're overlooking is the extreme relationship between magnetic force and air-gap. Air is an exceedingly poor conductor of magnetic lines of force. So while a diode does indeed slow the rate of drop in coil current (hence increased delay) once the armature comes unstuck from its seated condition, the effect of increasing air-gap is many times more influential than rate of decay in coil current. Went back to the workbench to look at the S704-1 in more detail. Here's the test setup: http://aeroelectric.com/Pictures/Schematics/Relay_Test_Setup.pdf Relay response with no coil suppression looks like this: http://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_without_Diode.jpg where we see the high voltage spike on the coil trace and a 2.5 mS dropout delay. WITH a coil suppression diode, we get relay response like this: http://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_with_Diode.jpg Dropout Delay is increased to 12.5 mS or about 5x longer than with the diode. This was the feature pointed out in the article you cited . . . where the authors extrapolated this into a commensurate slowing in contact spreading velocity (longer fires). However, when we take the diode off and look at transition time . . . http://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_NoSuppression.jpg From the time the contacts FIRST open until they first contact the opposite side is 0.6 mS. Let's put the diode back on and we get . . . http://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_Diode_Suppression.jpg Hmmm . . . transition increases to 0.75 mS, about a 25% increase NOT A 500% INCREASE. Let's go back an look at the traces I took where we were observing the arc in a spreading set of contacts with no diode . . . http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif Here I could see about 0.21 mS of "fire" as compared with . . . http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif about 0.23 mS arcing when the diode was in place. Hmmm, there was an increase but not a very big one. In both cases, observed arcing times were about 1/3 the total transition time. Now let us consider another feature of relays and contactors that REALLY drives service life issues. Take a look at: http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_with_Diode.jpg Where we see that after the first time the contacts touch, really get with the high-tempo hat-dance for perhaps several dozen closure and re-opening events. This means that for every operation of the switch on the panel, the contacts are getting 5-25 times more activity than the single switching event might suggest. Now look at: http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_without_Diode.jpg Well fooey . . . even with the diode off the contacts do the cat-on-a-hot-tin-roof routine. Let us further consider that when folks like those Tyco engineers evaluate service life, they're working in the laboratory test environment and evaluating products where service life is measured in the tens of thousands of operations . . . 50,000 typical. 250,000 is not unusual. Let us suppose that their paper was based on real statistical studies of dozens of relays with various coil suppression techniques and yes, there was an observable increase in mean operations between failures from 45,744 to 49,666 by "optimizing" the coil suppression. Hmmm . . . 10% . . . that IS significant to Tyco and probabably most of their customers. They didn't speak to this kind of study in the paper you cited and I'd like to believe they've done their homework. Let us assume their undocumented assertions WERE correct on the scale I suggested. How does this affect the OBAM aircraft builder who's switches, relays and contactors probably won't see 5,000 operations over the lifetime of the airplane? Further, environmental stresses will be root cause for most replacements of such devices in personally owned, non-revenue generating light aircraft, not electrical stresses. In any case, the 5x increase in drop-out delay DOES NOT extrapolate into a proportionate drop in contact life. >The common palliative is a diode AND zener in series, or better yet, a >bidirectional zener across the coil. They call these Transils, >Surmetics, Transorbs, TranZorbs, TransGuards, Mosorbs; the >list is endless. (Over-paid executives dream up these names.) They are >generic P6KE18CA bidirectional zeners. > >Jeeeeeze........ Eric, Of all the contributors to this list I expect more of you. We had some substantive discussions on the inner technical workings of various products and ideas in Plymouth a couple of years ago. You struck me as one who appreciates understanding and having a handle on the simple-ideas that go into your recipes for success. Please don't wave anyone's documents in the air as justification for an extrapolation of my infirmities. Let's not make this about you or me. May I suggest we explore, understand and then explain the physics. Make my day. Show me were I'm wrong. Bob . . . ________________________________ Message 6 _____________________________________ Time: 04:53:49 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: Coil Suppression Techniques (With Corrected Link) At 05:47 PM 5/21/2008 -0500, you wrote: At 07:42 AM 5/21/2008 -0700, you wrote: I have this weird Deja Vu feeling that we have covered this subject before. And I will save you the trouble Bob....I know you'll never agree, and you'll retort with a long quasi-techno piece and then stumble TO EXACTLY THE WRONG CONCLUSION. Coil suppression and relay contact arcing have been well studied: See: http://relays.tycoelectronics.com/appnotes/ Basically (ESPECIALLY with contactors) Do not use diodes for coil suppression unless you're hoping for greatly reduced relay/contactor life, so you can get stuck in a remote area and have an adventure. I know people like this but they usually don't build airplanes. Gotta'-Have-Drama-Dammit! You've cited that document before. And I've read it several times both before you cited it and after you cited it. Kindly point out to me where the authors offer DATA supporting an assertion that the plain vanilla diode coil suppression has a profound effect on relay life. They correctly asserted and I confirmed that diodes do indeed extend the time from switch opening until energized contacts begin to move. This is opening delay. They went on to extrapolate that opening delay translates directly into slower contact spreading velocity and extrapolated further that this translated to increased contact wear. I did the experiments and published the results that argue against their extrapolations. If you have some data to the contrary, please share it with us. Just because you've read some words under the letter head and over the signatures of persons in high places does not make their words golden unless they're supported by data from and understanding of repeatable experiments. Here's what sane people have figured out: . . . are you suggesting I am less than sane?? Mechanical relays and contactors depend upon magnetism generated by an electric current running through a wire coil. When the current stops, the magnetic field collapses. But the relay does not know the difference between a wire coil moving in a magnetic field (as in a generator) or a magnetic field moving in a wire coil (as in a collapsing magnetic field). Thus a large voltage1000V to 1500V typicallyis induced in the coil. This current goes the same direction the original current didso it slows the contact openingallowing arcing, chatter, bouncing, contact welding and even re-closure! Yikes! Go to your workbench, measure it, document it and share it with us. Show me where my data and interpretation of my data is wrong. The important feature of relay and contactor operation that you're overlooking is the extreme relationship between magnetic force and air-gap. Air is an exceedingly poor conductor of magnetic lines of force. So while a diode does indeed slow the rate of drop in coil current (hence increased delay) once the armature comes unstuck from its seated condition, the effect of increasing air-gap is many times more influential than rate of decay in coil current. Went back to the workbench to look at the S704-1 in more detail. Here's the test setup: http://aeroelectric.com/Pictures/Schematics/Relay_Test_Setup.pdf Relay response with no coil suppression looks like this: http://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_without_Diode.jpg where we see the high voltage spike on the coil trace and a 2.5 mS dropout delay. WITH a coil suppression diode, we get relay response like this: http://www.aeroelectric.com/Pictures/Curves/S704-1_Drop-Out_Delay_with_Diode.jpg Dropout Delay is increased to 12.5 mS or about 5x longer than with the diode. This was the feature pointed out in the article you cited . . . where the authors extrapolated this into a commensurate slowing in contact spreading velocity (longer fires). However, when we take the diode off and look at transition time . . . http://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_NoSuppression.jpg From the time the contacts FIRST open until they first contact the opposite side is 0.6 mS. Let's put the diode back on and we get . . . http://www.aeroelectric.com/Pictures/Curves/S704-1_D-E_Transition_Diode_Suppression.jpg Hmmm . . . transition increases to 0.75 mS, about a 25% increase NOT A 500% INCREASE. Let's go back an look at the traces I took where we were observing the arc in a spreading set of contacts with no diode . . . http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeNoDiode.gif Here I could see about 0.21 mS of "fire" as compared with . . . (Here's the right trace) http://www.aeroelectric.com/Pictures/Curves/704-1OpeningTimeWithDiode.gif about 0.23 mS arcing when the diode was in place. Hmmm, there was an increase but not a very big one. In both cases, observed arcing times were about 1/3 the total transition time. Now let us consider another feature of relays and contactors that REALLY drives service life issues. Take a look at: http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_with_Diode.jpg Where we see that after the first time the contacts touch, really get with the high-tempo hat-dance for perhaps several dozen closure and re-opening events. This means that for every operation of the switch on the panel, the contacts are getting 5-25 times more activity than the single switching event might suggest. Now look at: http://www.aeroelectric.com/Pictures/Curves/S704-1_Contact_Bounce_without_Diode.jpg Well fooey . . . even with the diode off the contacts do the cat-on-a-hot-tin-roof routine. Let us further consider that when folks like those Tyco engineers evaluate service life, they're working in the laboratory test environment and evaluating products where service life is measured in the tens of thousands of operations . . . 50,000 typical. 250,000 is not unusual. Let us suppose that their paper was based on real statistical studies of dozens of relays with various coil suppression techniques and yes, there was an observable increase in mean operations between failures from 45,744 to 49,666 by "optimizing" the coil suppression. Hmmm . . . 10% . . . that IS significant to Tyco and probabably most of their customers. They didn't speak to this kind of study in the paper you cited and I'd like to believe they've done their homework. Let us assume their undocumented assertions WERE correct on the scale I suggested. How does this affect the OBAM aircraft builder who's switches, relays and contactors probably won't see 5,000 operations over the lifetime of the airplane? Further, environmental stresses will be root cause for most replacements of such devices in personally owned, non-revenue generating light aircraft, not electrical stresses. In any case, the 5x increase in drop-out delay DOES NOT extrapolate into a proportionate drop in contact life. The common palliative is a diode AND zener in series, or better yet, a bidirectional zener across the coil. They call these Transils, Surmetics, Transorbs, TranZorbs, TransGuards, Mosorbs; the list is endless. (Over-paid executives dream up these names.) They are generic P6KE18CA bidirectional zeners. Jeeeeeze........ Eric, Of all the contributors to this list I expect more of you. We had some substantive discussions on the inner technical workings of various products and ideas in Plymouth a couple of years ago. You struck me as one who appreciates understanding and having a handle on the simple-ideas that go into your recipes for success. Please don't wave anyone's documents in the air as justification for an extrapolation of my infirmities. Let's not make this about you or me. May I suggest we explore, understand and then explain the physics. Make my day. Show me were I'm wrong. Bob . . . -- incoming mail is certified Virus Free. Checked by AVG. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 7 _____________________________________ Time: 05:05:38 PM PST US Subject: AeroElectric-List: Re: Coil Suppression Techniques. From: "Eric M. Jones" Sam, P6KE18CA is 0.6kW 18V contained in the part number. Digikey has them. I wouldn't ever buy airplane parts from Radio Shack. They use fallouts, defects, out of tolerance, rejects, mismarked, etc. The last parts I got from them went right into the trash can. This is another issue Bob and I always disagree on. Or you can buy mine...."SnapJacks". I include free shipping, a handful of Fastons, insulating tubing, etc. But whatever you do, just don't use diodes (especially on CONTACTORS). If you REALLY don't want to use bidirectional zeners, then use the several other recommended methods better than the diode. Eric -------- 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=184277#184277 ________________________________ Message 8 _____________________________________ Time: 10:31:00 PM PST US From: "sam@fr8dog.net" Subject: Re: AeroElectric-List: Re: Coil Suppression Techniques. Should I just use a diode in series with the snapjack, is it that simple? What about sizing the components? Thanks, Sam ---- "Eric M. Jones" wrote: ============ Sam, P6KE18CA is 0.6kW 18V contained in the part number. Digikey has them. I wouldn't ever buy airplane parts from Radio Shack. They use fallouts, defects, out of tolerance, rejects, mismarked, etc. The last parts I got from them went right into the trash can. This is another issue Bob and I always disagree on. Or you can buy mine...."SnapJacks". I include free shipping, a handful of Fastons, insulating tubing, etc. But whatever you do, just don't use diodes (especially on CONTACTORS). If you REALLY don't want to use bidirectional zeners, then use the several other recommended methods better than the diode. Eric -------- 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=184277#184277 ------------------------------------------------------------------------------------- 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.