Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber?
Any of the 1N400x series work well for this purpose. I've slowly learned the lesson that as a very small kit provider that it's often cheaper to use the same part in multiple kits even though it may be over-rated for some applications because the increased volume reduces the price, fewer stock keeping concerns, etc. Hence, my standard power diode for designs (reverse voltage protection, relay snubbing, etc.) is the 1N4007. And, there's no theory that I'm aware of predicting a 1N4007 diode has a slow turn-on time. What there seems to be the case is that because these diodes have a slow turn-off time (predicted by theory and confirmed in practice), hams have confused the two and reached the incorrect conclusion that slow turn-off = slow turn-on. Quite different physics are at work in these two conditions. Jack Bill Coleman wrote: On Apr 8, 2009, at 2:22 PM, Jack Smith wrote: The Cliff's Notes version is that the turn-on (note I said turn-on, not turn-off) time of a 1N4007 diode is sufficiently fast to be a very effective relay snubber. Interesting! It's always true that experiment trumps theory. Curious, though, that you would promote using a 1N4007 as a snubber for a 12 volt relay. It would make more sense to use a 1N4001, which has virtually identical characteristics as the 1N4007, except for the reverse breakdown voltage. The 1N4001, with a reverse breakdown of 50 volts, it will withstand the relay energizing voltage of 12 volts. The 1N4001 can be purchased for about a penny each in bulk. The 1N4007 is about four times more expensive. That's a three cent difference. And, you know, hams are cheap. grin Bill Coleman, AA4LR, PP-ASELMail: aa...@arrl.net Web: http://boringhamradiopart.blogspot.com Quote: Not within a thousand years will man ever fly! -- Wilbur Wright, 1901 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber?
I've used nothing but 1n4007's for years now for relay snubbers. They work just great. I don't bother with the slightly cheaper 1n4001's and that sort. You can get the 1N4007's cheap enough and use one type diode for everything. Some of the manufacturers don't put any identifcation on the diodes other than the cathode stripe which makes identifying the difference a pain in the butt. 73, Sandy W5TVW - Original Message - From: Bill Coleman aa...@arrl.net To: Jack Smith jack.sm...@cliftonlaboratories.com Cc: 'Elecraft' elecraft@mailman.qth.net Sent: Tuesday, May 12, 2009 9:54 PM Subject: Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber? On Apr 8, 2009, at 2:22 PM, Jack Smith wrote: The Cliff's Notes version is that the turn-on (note I said turn-on, not turn-off) time of a 1N4007 diode is sufficiently fast to be a very effective relay snubber. Interesting! It's always true that experiment trumps theory. Curious, though, that you would promote using a 1N4007 as a snubber for a 12 volt relay. It would make more sense to use a 1N4001, which has virtually identical characteristics as the 1N4007, except for the reverse breakdown voltage. The 1N4001, with a reverse breakdown of 50 volts, it will withstand the relay energizing voltage of 12 volts. The 1N4001 can be purchased for about a penny each in bulk. The 1N4007 is about four times more expensive. That's a three cent difference. And, you know, hams are cheap. grin Bill Coleman, AA4LR, PP-ASELMail: aa...@arrl.net Web: http://boringhamradiopart.blogspot.com Quote: Not within a thousand years will man ever fly! -- Wilbur Wright, 1901 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.329 / Virus Database: 270.12.27/2112 - Release Date: 05/13/09 07:04:00 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber?
On Apr 8, 2009, at 2:22 PM, Jack Smith wrote: The Cliff's Notes version is that the turn-on (note I said turn-on, not turn-off) time of a 1N4007 diode is sufficiently fast to be a very effective relay snubber. Interesting! It's always true that experiment trumps theory. Curious, though, that you would promote using a 1N4007 as a snubber for a 12 volt relay. It would make more sense to use a 1N4001, which has virtually identical characteristics as the 1N4007, except for the reverse breakdown voltage. The 1N4001, with a reverse breakdown of 50 volts, it will withstand the relay energizing voltage of 12 volts. The 1N4001 can be purchased for about a penny each in bulk. The 1N4007 is about four times more expensive. That's a three cent difference. And, you know, hams are cheap. grin Bill Coleman, AA4LR, PP-ASELMail: aa...@arrl.net Web: http://boringhamradiopart.blogspot.com Quote: Not within a thousand years will man ever fly! -- Wilbur Wright, 1901 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber?
I have used 1N4007 diodes for this purpose and had no trouble! The last relay I took care of was the keying relays in the old Navy TCS-12 transmitter I have. If you get across the key contacts when you are sending, the collapsing relay coil fields will give you quite a belt! Diode installed and no more problems! 73, Sandy W5TVW - Original Message - From: Jack Smith jack.sm...@cliftonlaboratories.com To: 'Elecraft' elecraft@mailman.qth.net Sent: Wednesday, April 08, 2009 1:22 PM Subject: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber? To answer, I hope definitively, the question is a 1N4007 power diode too slow to be used as a relay coil snubber, I've updated my December 2007 diode turn-on time measurements with data taken this morning showing the effectiveness of (a) no snubber; (b) 1N4148 snubber and (c) 1N4007 snubber with a typical small relay switched by a 2N7000 MOSFET transistor. I've also looked at the how much the relay release time lengthens when a snubber is added. (Of course, the specifics are dependent upon the particular relay but the concepts are similar.) The details are at http://www.cliftonlaboratories.com/diode_turn-on_time.htm The Cliff's Notes version is that the turn-on (note I said turn-on, not turn-off) time of a 1N4007 diode is sufficiently fast to be a very effective relay snubber. The data also shows that a diode or MOV or other technique should be used to control inductive field decay voltages. Jack K8ZOA www.cliftonlaboratories.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.285 / Virus Database: 270.11.47/2047 - Release Date: 04/08/09 05:53:00 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber?
To answer, I hope definitively, the question is a 1N4007 power diode too slow to be used as a relay coil snubber, Just curious -- over the years, I've seen references to the main purpose of the snubber diode being used; (1) to decrease the action time of the relay, since the decaying flux of the relay coil tends to keep the contacts engaged (NO), or disengaged (NC) longer than necessary after voltage is removed from the coil; and (2) to primarily protect a solid-state switching device (e.g., an open NPN collector) from damage, also being caused by the snap of the decaying flux of the relay coil. I realize both uses of the diode are valid, but it seems that unless there's an extremely high flux developed by coil, the primary purpose of the diode is for relay speed, rather than switching device protection. Paul, W9AC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber?
The quick test I did today used a common 2N7000 MOSFET to switch a physically small relay typical of those used in ham gear. I think this is a reasonably common arrangement and I've used it in the past myself. The turn-off voltage exceeds the 2N7000's maximum permitted source-drain voltage of 60 volts. What happens is that the 2N7000 breaks down at 70-75 volts and acts like a Zener diode. I'll leave it to the designer to decide whether it's a good thing or a bad thing to have the 2N7000 break down with every diode switch cycle. I don't recall seeing a caution in the 2N7000 data sheet recommending that the device not be operated in a mode that causes it to break down but it seems to me that it isn't a good idea for a reliable design. The relay coil resistance will limit the peak current through the 2N7000 when in break down mode, but it still leaves me uncomfortable. Jack Paul Christensen wrote: To answer, I hope definitively, the question is a 1N4007 power diode too slow to be used as a relay coil snubber, Just curious -- over the years, I've seen references to the main purpose of the snubber diode being used; (1) to decrease the action time of the relay, since the decaying flux of the relay coil tends to keep the contacts engaged (NO), or disengaged (NC) longer than necessary after voltage is removed from the coil; and (2) to primarily protect a solid-state switching device (e.g., an open NPN collector) from damage, also being caused by the snap of the decaying flux of the relay coil. I realize both uses of the diode are valid, but it seems that unless there's an extremely high flux developed by coil, the primary purpose of the diode is for relay speed, rather than switching device protection. Paul, W9AC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber?
Hi, I have used the diode snubber in all designs of relay control from small reed to large contactors. I usually check the series resistance of the relay and the non solid state device activation and measure the voltage kick. I then use ohms law to determine the peak current that would occur against the relay resistance and size the diode accordingly. Most of the time the 1N4000 series are well suited for small relay applications. When in doubt, measure the relay parameters.. Mel, K6KBE --- On Wed, 4/8/09, Jack Smith jack.sm...@cliftonlaboratories.com wrote: From: Jack Smith jack.sm...@cliftonlaboratories.com Subject: Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber? To: Paul Christensen w...@arrl.net Cc: 'Elecraft' elecraft@mailman.qth.net Date: Wednesday, April 8, 2009, 2:43 PM The quick test I did today used a common 2N7000 MOSFET to switch a physically small relay typical of those used in ham gear. I think this is a reasonably common arrangement and I've used it in the past myself. The turn-off voltage exceeds the 2N7000's maximum permitted source-drain voltage of 60 volts. What happens is that the 2N7000 breaks down at 70-75 volts and acts like a Zener diode. I'll leave it to the designer to decide whether it's a good thing or a bad thing to have the 2N7000 break down with every diode switch cycle. I don't recall seeing a caution in the 2N7000 data sheet recommending that the device not be operated in a mode that causes it to break down but it seems to me that it isn't a good idea for a reliable design. The relay coil resistance will limit the peak current through the 2N7000 when in break down mode, but it still leaves me uncomfortable. Jack Paul Christensen wrote: To answer, I hope definitively, the question is a 1N4007 power diode too slow to be used as a relay coil snubber, Just curious -- over the years, I've seen references to the main purpose of the snubber diode being used; (1) to decrease the action time of the relay, since the decaying flux of the relay coil tends to keep the contacts engaged (NO), or disengaged (NC) longer than necessary after voltage is removed from the coil; and (2) to primarily protect a solid-state switching device (e.g., an open NPN collector) from damage, also being caused by the snap of the decaying flux of the relay coil. I realize both uses of the diode are valid, but it seems that unless there's an extremely high flux developed by coil, the primary purpose of the diode is for relay speed, rather than switching device protection. Paul, W9AC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber? [END of Thread]
Let's end this thread for now. I think we've pretty much beaten it to death. ;-) 73, Eric WA6HHQ Elecraft List Moderator __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber?
The flux can be very considerable! As the flux collapses it can induce a very high voltage transient across the coil far exceeding the voltage produced to energize the relay. There is a certain amount of energy stored there in many instances. The 'back EMF pulse can wreak havoc with solid state gear and shock the hell out of someone who happens to be across the circuit when the field collapses! Seems like I was havinga discussion of neon tubes (NE-2?) across relay coils in the old ARC-27 UHF aircraft transceiver (a true boat anchor piece of gear!). These were probably primarily to limit the pulse to whatever the ionization potential of the NE-2 is. (probably around 60-65 volts?) Silicon diodes didn't exist in those days or they probably would have been used instead. 73, Sandy W5TVW - Original Message - From: Paul Christensen w...@arrl.net To: 'Elecraft' elecraft@mailman.qth.net Sent: Wednesday, April 08, 2009 4:11 PM Subject: Re: [Elecraft] Can a 1N4007 Be an Effective Relay Snubber? To answer, I hope definitively, the question is a 1N4007 power diode too slow to be used as a relay coil snubber, Just curious -- over the years, I've seen references to the main purpose of the snubber diode being used; (1) to decrease the action time of the relay, since the decaying flux of the relay coil tends to keep the contacts engaged (NO), or disengaged (NC) longer than necessary after voltage is removed from the coil; and (2) to primarily protect a solid-state switching device (e.g., an open NPN collector) from damage, also being caused by the snap of the decaying flux of the relay coil. I realize both uses of the diode are valid, but it seems that unless there's an extremely high flux developed by coil, the primary purpose of the diode is for relay speed, rather than switching device protection. Paul, W9AC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.285 / Virus Database: 270.11.47/2047 - Release Date: 04/08/09 05:53:00 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
