I found a great very simple LFO on schematic from a phaser of 1981, I tried it on 2 designs with great success, here is a link
https://www.freestompboxes.org/download/file.php?id=37873&mode=view
I added a depth pot adding a B1K before the led with
1 transitor emitter
2 led
3 ground
I, as well...