Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: luthierwnc on July 10, 2021, 12:59:02 pm
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Hi All,
I'm fiddling with an amp design that can go A/B/Y to two channels from a single input. The internal switches will be typical Dumble-style relays with a dedicated 12 VDC supply. The 'Y' switch takes the cathode of the relay coil to ground across an LED and a resistor to collapse the field. The A/B part I haven't tried before. I was thinking of taking a line from both the back end of the coil and the live 12v hot to the second switch. In the normally-closed position on the footswitch, the coil is unaffected and I light half of a bi-color LED with the necessary dropping resistor. In the normally-open position, the coil collapses going through the other color on the LED.
In the attached illustration I'm showing both the relay and foot switches with the pole in the center position and the throws up and down. Relays often have the pole on the top of the three lugs. I'll etch the board based on which ones I use.
Any thoughts? Thanks for looking, Skip