Yes, I agree. Perhaps an RC snubber would be good. It all depends on the timing requirements of the application. If the 1N4007, with its junction capacity (that actually increases as it becomes more reversed biased) does not switch (is held off) until the transient cycle has ended, it will do nothing to capture the transient. In this application, a 12 volt relay can generate a very large spike. It can also destroy the switching transistor if the cycle hits right. The snubber would slow the rise time dPhi/dt. Rich :-) ----- Original Message ----- From: "David VanHorn" To: "Microcontroller discussion list - Public." Sent: Monday, February 06, 2006 7:51 PM Subject: Re: [EE] Transient Suppression - was Re: [ee] 3904 base resistor > > >> >> I suspect that "slow" diodes (eg 1N400x series) might even produce less >> EMI.... the slowness being evident as an equivalent capacitance that >> suppresses dv/dt. I also could be totally wrong here :-) An RC snubber >> would >> be a better idea. > > > Reminds me of a shipment of russian relays we got in once. > They had series R/C supressors across the coils. > Molded in red plastic. > > (red supressors on russian relays.. am I the ONLY guy that finds this > funny?) > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist