adding sort of tap tempo to pedals

[hooperharp]

Anybody knows how to make tremolo pedals "start" the cycle at the push of a switch? So that when the effect is on I step on a switch and the lfo starts again at that moment. What would I have to look for with a multimeter?
This would come in handy with an effect like the Repeat Percussion in slow settings, or any tremolo that can get very choppy. Or delays. I guess tap tempo does other things, but i'm thinking more of just a momentary switch that intereupts the lfo so that it starts again "from zero" (hope someone understand what i'm trying to say  ).
I think Doug Deeper does something like this with the Pitch Pirate so that the LFO doesn't get in the audio path with the effect ON and also so that every time the effect is switched ON again the pulses start at the same point of the cycles. Hope this makes sense.

Andy Hooper

[midwayfair]

In an op amp design, I think you can momentarily short one of the Vb divider resistors. However, this isn't going to put you at the top of the cycle necessarily. It might start from the middle or bottom of the cycle. But it will definitely start the cycle from the same point every time.

Really the only way I know to do what you're talking about for certain is a microcontroller, like the TAPLFO. Despite the cost, that thing is not difficult to work with.

[alanp]

Would putting a normally closed momentary in series with the power going to the LFO opamp work?

[midwayfair]

Would putting a normally closed momentary in series with the power going to the LFO opamp work?

Yes, but you'd short the power. That's why I suggested shorting one of the VB resistors. Still interrupts the oscillation but doesn't risk damage to anything else in the circuit.

[alanp]

No, I meant so that there is NO power going to the opamp's power pin at ALL when the stomp is down -- the switch disconnects power, it doesn't short. Normally closed, not open.

[hooperharp]

I was thinking about something in the veins of that, shorting the power with a momentary switch. If it won't damage anything of course. What should I look for with a multimeter to have an idea of where I could try to short stuff? I'll breadboard something and give it a try and see if something works out.

[alanp]

No, not shorting the power, disconnecting it when you step on the stomp (hence momentary normally-closed, not normally-open.)

[hooperharp]

yes, that, not actually shorting the 9V.
I'll start tinkering next week, need some rest from building pedals, just finished the 27th.
Before posting about the next idea which might not work on the discussions forum, what do you guys think about adding a hold switch to a pt2399 delay? Saw this video from colin on his modified dano pb&j
http://www.youtube.com/watch?v=UBXTdAzRFLw
Those seem to use the pt2395. It would be cool to have a hold switch on a delay, not so much as a looper but as a sort of lo fi ehx freeze pedal.
Midwayfair your youtube videos are great!

[LaceSensor]

I think you should look into the trigger circuits used in Lovetone pedals, bot ph the wobulator and flanger have the ability to synch in a way you are I think describing.