Sequencer type design? (noise maker)

[mattpocket]

Anyone know of a basic sequencer type setup where a load of pots are used to set a pitch and then some sort of IC can switch between each pitch to make a sort of musical loop?

[R.G.]

Go look up the CD4051. It's a CMOS switch which is the equivalent of a 1P8T rotary switch. It can switch any one of eight pins to one pin.

You can set up the logic which drives the select pins so that you can use multiple of these so you can get 1:16, 1:24, 1:32 and so on.

You drive this with three address pins, A , B and C. The pins are digital, so that 0=0V, 1 = power supply. The selected channel is the binary value of the address pins, so if you have pins like:

C B A  Selected channel
0 0 0   0
0 0 1   1
0 1 0   2
0 1 1   3
1 0 0   4
1 0 1   5
1 1 0   6
1 1 1   7

Typically, to do a sequencer, you would drive the address pins with a binary counter, which counted in that order. There are CMOS chips that do this directly. Finally, you put a variable speed clock signal into the counter, and it ticks and the switches move by one increment per clock tick.

You could also do something similar about 18 different ways using CMOS logic to count and decode into one-of-N bits and use the active bits to turn on one switch in a CMOS CD4066 switch chip or a discrete JFET.

A single chip solution to the counter would be to use a uController to read a pot for speed, then output one-of-N bits to the switches directly.