Adding a LFO to a Pedal

[Rqtten]

Hello everybody,

I recently built a guitar synth, which is cool on its own, but since I have space for other Pots, I'd like to add a LFO, that can control either a filter or the volume of the Output signal(preferred switchable).
I'm asking myself if this is possible without a LDR/LED coupling.
And if I wanted to add a tap tempo switch with a NO Footswitch, is it necessary to add a designated tap tempo IC, or is there a circuit with basic parts (like Opamps, common Transistors etc.) which will work?

[bartimaeus]

it's basically impossible for us to guess how the lfo could control the filter or volume when we don't know how those are designed.

you should probably just get an electric druid tap tempo lfo. has everything you want in a single chip, and it'll be easier to implement and almost certainly more versatile than building a separate lfo (at least compared to the standard stompbox lfos that run on (9v).

[strungout]

https://www.diystompboxes.com/smfforum/index.php?topic=124767.0

there's another link in there about LFO adding to stompboxes.

[Rqtten]

Thanks for the Replies, I'm going to look at it.
I haven't added a filter yet, it's just a Synth with switchable octave, and mixing of waveforms.
I'm going to try to add just a op amp LFO with a transistor which switches a LP on, and go from there.

[Marcos - Munky]

But that synth does have a schematic/layout, right?

[ElectricDruid]

I'll have a little toot on my own trumpet and mention the StompLFO here. It'll provide the tap tempo feature you want (or you can sync it to pulses from a drum machine, sequencer, whatever) and it provides an LFO output. There are eight waveforms. More details here:

https://electricdruid.net/electric-druid-chips-the-next-generation/
https://electricdruid.net/product/stomplfo/

How you actually connect it up to the Filter and VCA depend on the details of those circuits, which you haven't given us yet...