Giving an op-amp +5v/-15V

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Ferniff
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State Variable Filter
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Post by Ferniff »

Hello all, I'm messing around with an Alembic filter made from another user here. Everytime I make my own charge pump, it creates a lot of noise. So I just buy a voltage converter off Amazon. The first one gave me +/- 15v which was fine but I wanted to lower the headroom. I just got another variable converter that I can bring down to +5 volts but instead of -5v it gives me -15v. It stays -15v no matter how I adjust it.

Would this have a negative impact or any?

Voltage converter I bought; there is a review that mentions the same issue I'm having. I'm just looking for something that can give me a clean +/- 5-9volts.

I can't seem to paste the amazon link, but this is what it's called:
Boost Buck Voltage Converter, DC-DC 5V-24V to +/-3V-30V Step UP Down Power Supply Module Adjustable 20W Positive Negative Dual Output Voltage Charging Converter for Amplifier
https://tinyurl.com/mr3aekef

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bmxguitarsbmx
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Post by bmxguitarsbmx »

That converter is 20W. Probably a little overkill. I have used the XL6007 modules with pedals reliably, and they are not only smaller, but cheaper. What you want to do is get one that is maybe +/-12V, then use lm7909 and lm7809 get get a nice clean, low noise +/- 9V to run your circuit.


I don't even always do that. I always add a reservoir cap to the input and two on the output as well. Then, depending on the current draw of the circuit, just do a RC filter. Especially if it is op-amp based (op-amps usually have the ability to reject the power supply noise), this can be fine. Using regulators is the professional thing to do though.

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Ferniff
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Post by Ferniff »

bmxguitarsbmx wrote: 28 Jun 2024, 20:22 That converter is 20W. Probably a little overkill. I have used the XL6007 modules with pedals reliably, and they are not only smaller, but cheaper. What you want to do is get one that is maybe +/-12V, then use lm7909 and lm7809 get get a nice clean, low noise +/- 9V to run your circuit.


I don't even always do that. I always add a reservoir cap to the input and two on the output as well. Then, depending on the current draw of the circuit, just do a RC filter. Especially if it is op-amp based (op-amps usually have the ability to reject the power supply noise), this can be fine. Using regulators is the professional thing to do though.
Thank you.

I've been using it for a while and haven't had any issues, so I guess +5/-15v is alright for a state variable filter. Every time I've tried to make my own charge pump, it just introduces a lot of noise.

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