Random Switching

[Barcode80]

So, I have this rather odd friend who wants me to build him a pedal which randomly will select 1 of 4 or 5 effects at random when turned on. basically they will be noise makers (fuzz factory, etc.) and he wants the unit to spontaneously select one of the effects when activated. I was thinking this may be accomplished by setting up an LFO which will pulse a relay or cmos switch while the pedal is OFF. then, when switched on, the LFO would stop and whatever effect was activated at the time would be the "chosen" effect. thoughts?

[PRR]

> setting up an LFO which will pulse a relay or cmos switch

Doesn't have to be a specially LOW-FO, only slow enough for a counter.

When engaged, you can either latch the count or just stop the LO and select an output according to count.

If you don't like re-inventing wheels, http://www.doctronics.co.uk/4017.htm

You can switch audio with either an LED-optoR in place of each LED, or with 4051/4052 CMOS switches (ponder the supply voltages; it would be best to have +/-9V supply for the switch).

[soggybag]

I was thinking a Micro Controller might work well. After that last description the counter is sound pretty easy.

[Barcode80]

> setting up an LFO which will pulse a relay or cmos switch

Doesn't have to be a specially LOW-FO, only slow enough for a counter.

When engaged, you can either latch the count or just stop the LO and select an output according to count.

If you don't like re-inventing wheels, http://www.doctronics.co.uk/4017.htm

You can switch audio with either an LED-optoR in place of each LED, or with 4051/4052 CMOS switches (ponder the supply voltages; it would be best to have +/-9V supply for the switch).

wow, that seems easy enough. so basically, sub in a vactrol in place of the LEDs, and the resistance of the LDR in the vactrol would basically silence that output. so i could do something like this:

Input buffer->Effect Circuit with output tied to the LDR side of the vactrol, other leg of the LDR side tied to an output buffer

and then i can have the switch connect the ENABLE to +9v when the effect is activated, freezing the count on one output. then it will resume once the 9v is disengaged. does that sound right?