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Relay bypass power supply issue

Started by helos, February 16, 2018, 05:43:17 AM

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helos

Hello everyone,
I'm trying to develop a bypass system based on a relay (Takamisawa na5w-k), I'm also using a microcontroller activated by an SPST switch, all powered by a 78L05 at 5V...
Basically everything works, except for a really annoying pop noise when the relay changes its state.
The funny thing is that the exact same circuit on the breadboard doesn't do any kind of noise... After many tests I've figured out that the problem resides in the power supply.

It must be said that I use a 82R resistor together with a 100uF cap at the input of the power supply, to filter out some high freq. power noise, now:
- if the input of the 78L05 is connected AFTER the 82R (being so connected to the supply rail of the rest of the effect pedal) there's the pop noise when I press the switch
- if the input of the 78L05 is connected BEFORE the 82R the pop noise is very much reduced but not completely eliminated...

Can you help me with this issue??


madbean

We had a similar problem with our switching system with Function FX. Our setup is slightly different but we found that rather than running the regulator after the DC filtering used for the audio portion, tying it directly to the PS with a 1N4001 in series with the regulator input fixed the problem. Also, you can try incorporating a temporary mute at the circuit output if you haven't done so. And, also check to see if your LED switching on/off is contributing.

helos

Quote from: madbean on February 16, 2018, 07:09:23 AM
We had a similar problem with our switching system with Function FX. Our setup is slightly different but we found that rather than running the regulator after the DC filtering used for the audio portion, tying it directly to the PS with a 1N4001 in series with the regulator input fixed the problem. Also, you can try incorporating a temporary mute at the circuit output if you haven't done so. And, also check to see if your LED switching on/off is contributing.

Thank you very much Bryan