Anyone able to help? The aim is an audio volume control composed of 40 separate relay-operated L-pad attenuators per stereo channel. Over-all (human) control is via an IR remote or the amplifier touch control screen; there is no mechanical control as such - no "knob". Why do this? Pure resistor networks sound sonically far superior in a high-end stereo than even the best motorised Alps pot, and a universe better than a solid state pot. The relay and resistor networks are not a problem, nor are the remote control and touch screen circuits; my design friend and I know how to do these. But the successive control of the relays is a problem. Microprocessor? Or a circuit like this ---http://www.technologystudent.com/elec1/count1.htm --- using a 555 timer and 4017B ? The need (and the problem) is: the control circuit has to move up/ down through positions 0-39 providing successive pin outputs. Each of these switches on a separate relay, thus giving an incremental or decremental attenuation according to the volume "up" or "down" direction. Around a 20 second period (adjustable via RC network?) is needed to scan the array of relays (i.e going from max. to min. or vice versa), and the system needs to store the "position" when switched off, so the currently selected relay stays on. And when the control system is switched on again - either to adjust the volume up or down - it needs to "know" which the currently selected position is to pick up from. Hope that's explained OK. Anyone know how best to design the control circuit? Just some rough guidelines and/ or a pointer to the best ICs or m/processor would be fantastic. Thanks.