I think this is the thread I'm looking for... I'm putting several DIY effect boards (Compressor, Delay, Chorus, Crunch, Heavy Distortion) into the shell of a dead Pod XT Live... My plan is to keep the momentary switches that are already built into the XT Live and use those to control the bypassing of the effect pedals...
So what I'm trying to construct is a circuit where the audio input enters the circuit... and depending on the toggle state, it's routed to either the effect pedal or directly to the output of the circuit... If the toggle is "closed", then the signal going to the output should also be from the effect pedal, not the input state...
I'm pretty sure I can do this with two SPDT relays (and a couple 2n3904s to keep the mA's off the Arduino pins)..
Relay 1: Arduino Pin x -> Coil, Common -> audio Input, NO ->Relay 2 NO, NC -> Effect In
Relay 2: Arduino Pin y -> Coil, Common -> audio Output, NO -> Relay 1 NO, NC -> Effect Out
So... if I wanted to use a DPDT relay... would that be...
Arduino Pin x -> Coil, Com1 -> audio Input, NO1 -> NO2, NC1 ->Effect In Com2->Audio Output, N02>N01, NC2>-Effect Out?
Well, it turns out that the relays aren't going to cut it. Two problems with relays:
The mechanical switch translates to an audible pop in the amp.
The audio signal is too weak to overcome the natural resistance between COM and NO.
In short, my first attempt (thankfully I hadn't bought a bunch of relays yet) failed utterly. All that was produced by my amplifier was a great deal of humming a very loud POP every time I switched the relay.
So... it's off to semiconductors... I found some great chips like the NLAS3799 (with very low resistances) but they're surface mount only... If I were designing a commercial circuit, it would be my option, but I'm building this switch array on a vero stripboard...
Does anybody know of a good IC that acts like a DPDT relay but in DIP form?
Thanks! This is close, and I could probably use this chip (though at $5.00 a pop at Mouser and back ordered 7 weeks... this particular solution would probably break the bank).
The Max4526 flip flops connections between 1/2 and X/Y... That's fine, at least on the output end of the circuit, because you just put dry signal on 1, wet signal on 2, and path to the rest of the effect chain on Y...
I suppose it could work on the input side as well... input goes in 1, Y goes to pin 1 of the output Max4526 and X goes to the effect to get processed... output of the effect goes to pin 2 of the output Max4526...
I was hoping for a one chip per effect idea like the NLS3799...
Input -> Com1, NO1 -> NO2, NC1 -> effect for processing
Effect out ->NC2, NO2 -> NO1 (Implied), Com2-> rest of effect chain...
I suppose I could leave the input switch off entirely, send the input signal to both pin 1 of the Max4526 and to the effect, effect out to pin 2, and Y to the effect chain, but won't that cause some signal loss if I split the signal like that?