I have a circuit where I'm switching the primary of an audio transformer using relay NO/NC contacts. A partial schematic is shown.
![]()
https://i.stack.imgur.com/711Hq.jpg
The problem is that I'm getting inductive kick whenever the contacts close to switch off the input. This can be seen in the scope image below and is audible as a "pop" at the output.
![]()
https://i.stack.imgur.com/R70Tg.jpg
I have the high pass on the secondary and impedances right where I want them, with a corner frequency at 99.6kHz and slight underdamped peak at about 56kHz. That gives a relatively flat response up through 20kHz. Part of the issue is also that the input should be able to handle 3Vrms, and the spikes are not that high (generally 2-4V). I've read that a snubber circuit is commonly used for this, but not sure where to start. If treated as a low pass filter(an article for you to comprehend filter: http://www.apogeeweb.net/article/35.html), the large 220uF cap as part of the snubber would need a tiny resistor to pass audio frequencies, and I think would throw off the impedances.
Would appreciate any useful input.
I have a circuit where I'm switching the primary of an audio transformer using relay NO/NC contacts. A partial schematic is shown.
![]()
https://i.stack.imgur.com/711Hq.jpg
The problem is that I'm getting inductive kick whenever the contacts close to switch off the input. This can be seen in the scope image below and is audible as a "pop" at the output.
I have the high pass on the secondary and impedances right where I want them, with a corner frequency at 99.6kHz and slight underdamped peak at about 56kHz. That gives a relatively flat response up through 20kHz. Part of the issue is also that the input should be able to handle 3Vrms, and the spikes are not that high (generally 2-4V). I've read that a snubber circuit is commonly used for this, but not sure where to start. If treated as a low pass filter(an article for you to comprehend filter: http://www.apogeeweb.net/article/35.html), the large 220uF cap as part of the snubber would need a tiny resistor to pass audio frequencies, and I think would throw off the impedances.
Would appreciate any useful input.