dpresley58

Hi, I'm trying to figure out a circuit that would sequentially "scroll" through one of three audio inputs, and the logic is kicking my keister. Is there a cookbook approach to this, or possibly a chip that already does this? Thanks in advance.

I see what you're saying... Not particularly married to the switching situation - the positive could be used just as easily, since it only really amounts to breaking the battery leads with a switch. I'll look into the emitter-follower. And thanks...

What would be a good method of doing this while keeping component count down? A decent-sized cap (100uf) with a pull-down resistor to ground on the way from the switch to the board?

Thanks. The schematic is under Topic 9 of this link. http://runoffgroove.com/fetzervalve.html Although the author used pots for dialing in the source and drain resistors, I've calc'd resistors for the individual transistors. He shows a small breadboard jig for measuring these values. Since my application is stereo, I had to find 2 trannies that were more or less matched. I'm using the J201, by the way.

I've built a small transistor-based preamp and powered it with a standard 9v battery. Its using a SPST switch to which the ground is hooked to turn it on. The problem is that there is a substantial thump when the switch is thrown, and I'm looking for a solution with a small component count that would slowly ramp the power to the circuit in hopes that approach would eliminate the pop. Is there a simple approach to this?