Kay Tremolo - lfo ticking

[SprinkleSpraycan]

i have this circuit on a breadboard right now. its really great but there is an audible lfo ticking. after poking at it for a week i cant figure out how eliminate it. is there a way?

[ElectricDruid]

I don't know, but the usual suspects would be a good place to start: Make sure that the ground paths for the LFO and the audio parts of the circuit are *completely* separate, and only meet where the power comes in.

In this case, that means T4, the Speed pot, and the LFO LED should all have a ground that is totally separate from the rest of the circuit.

The +V power is separated already by that 1K2 resistor, but the same principles apply. Ideally, the LFO's +V power input should be a separate wire to keep any current it draws away from the audio side of the circuit. Since this is not an op-amp-based circuit, you don't get the advantage of the power supply rejection ratio (PSRR) that you get with op-amps. That makes this circuit more fussy, although simpler.

I can't see clearly whether the Das Musikding PCB layout does any of this, but if it doesn't, maybe it ticks too!

[antonis]

In case of Tom's suggestions don't work, try to place the LED between R12 and T4 Collector..
(it will work 180^o out of present phase but I presume you don't mind..)

[duck_arse]

that circuit shows no supply bypass caps whatsoever. at least one might help.

[SprinkleSpraycan]

that circuit shows no supply bypass caps whatsoever. at least one might help.

I did do that. A 100uf and 100nf. It made the ticking softer. Any improvement is good.

[SprinkleSpraycan]

In case of Tom's suggestions don't work, try to place the LED between R12 and T4 Collector..
(it will work 180^o out of present phase but I presume you don't mind..)

I'll try all this today. Cool tip about the led.

[SprinkleSpraycan]

Success! Thanks guys.