Watts speaker relay

[wattsabundant]

If I understand the proposal, the R/C network is in parallel with the speaker. Assuming the speaker is largely an inductive load, the added snubber would effectively appear as a net resistive load back on the amplifier during normal operation. I must be missing something as I don't see the benefits of the snubber.

 

[gene french]

Yep, did not make the weekend get away in Israel.

glad you made it back...that part of the world worries me..

 

[mlucitt]

If I understand the proposal, the R/C network is in parallel with the speaker. Assuming the speaker is largely an inductive load, the added snubber would effectively appear as a net resistive load back on the amplifier during normal operation. I must be missing something as I don't see the benefits of the snubber.

The snubber is an attempt to reduce contact arcing in the event of a amplifier failure when DC voltage has caused the relay to open the contacts.
The capacitor charges, reducing the arc, and resistor bleeds off the capacitor.

I may try it and see if the Snubber has any effect on the load of the amplifier.

 

[GeorgeP]

Hi George here: I powered up one 700W Relay board at 100V, then put the inputs to a variable supply to have a look. I measured +10V and -7V to trip off relays. I was not happy with that. I decided to try to use the UPC 1237 chip, powered by a separate regulator. That will result in a much lower DC offset trip point. I'm in the process of doing it now...See attached schematic and PCB (not yet tested or released)... If it works out good on the bench test breadboard, I'll get a board made using the same size board and mounting technique. I already designed it, and if good, I'll tweak it, order 3 boards to start. Its more complicated this way, but I want to detect the lower DC offset point and set the frequency and delays independently.

OK...Here is an updated drawing that will be better, and has a\measured voltages on it. This worked well in my 700 W series 1 amplifier.