Hello. I hope this is the right section to post this question about my project.
I'm working to the renovation of a a tube amp and needed to have internally two relay (one for switch between 2 different master volume, the other to insert the lead channel) with 2 commands (on the front panel / by a footswitch).
Unfortunately the only available voltage is the 6,3Vac of the heaters, but I cannot use it continously.
The other issue is that the Zettler relay (a bistable latching single coil) need +/- in one sense to switch in one sense, and -/+ (reverse) to switch in the other sense.
The solution I found, also looking to a different post on this websites is the following (attached the layout of the whole project, the specific part I'm talking about is at the bottom of the layout):
1) Converting the 6,3Vac to Vdc
2) Sending to the coil the + Vdc (from the front panel or from the footswitch) to switch in one sense, and charging an electrolytic cap connected to the other (-) pole of the coil
3) When the cap is charged the coil doesn't consume nothing more, and the only consume is related to the led
4) When I switch off the + supply the cap inverts the polarity on the coil and the relay switch on the other side
I tested and the single command works good.
My question now is how to manage two of this small circuits with the same supply without one interfere with the other.
I introduced two diodes on the negative line but I'm not sure it's correct.
Your opinion? Thanks
PS Sorry for my orrible english