So I spent some time this weekend playing with an LM567 IC, which is a Tone Decoder, basically used to modulate incoming signal, so (pls forgive me if this is nonsense) I'm assuming it is generally used as some kind of modulator for microprocessors and whatnot to decode signals on a frequency spectrum. It's super cool and can make some wild sounds, but there's a constant hum coming out of it at the chip's modulation frequency, and I'm wondering if there's some kind of analog way to filter that out. I've come up with a few extravagant solutions that involve using a second chip & dual gang pot to keep the frequency sweeps of both chips, then send the one w no guitar input to an inverting op amp and basically use phase cancellation to kill it, but that would complicate my switching options greatly & also I worry that'd kill the effect by cancelling out the modulation pitch.
I'm also wondering if this might be a problem with breadboarding certain ICs. I've had a lot of trouble getting certain designs to sound nice and noise-free on breadboards. Mainly when I use things like an NE555, PT2399, or the LM567 in this case. In fact, I had a 555 hooked up on the same breadboard and the oscillation pitch would carry over into the output audio just from sharing the same power and ground rails. Once I disconnected power it stopped. Is this normal for some/all breadboards or just the cumulative result of proximity of long exposed leads experiencing dynamic electromagnetic moments and all that good stuff? And is there a way to get rid of it?