I am looking for a relatively low part circuit that would produce one-shot ramps (downward) and the decay rate can be voltage controlled. This would essentially be a voltage controlled decay envelope.
Is there maybe something 555 based that is suitable?
-voltage would be peak of 5v.
-duration (set by timing cap surely) would be min 0.5ms max. 10s
-exponential or linear decay
-tolerance? not sure...
-load not important (I will buffer this voltage)
-Trigger: 5V trigger pulse to initiate the decay envelope.
Do you need the full 0.5ms to 10s variation solely using the control voltage with no range switching? That's a large range (20,000:1) to vary without range switching.
I was going to ask the same question . Doing it without range switching, in the analogue domain, would be extremely difficult to achieve with any degree of accuracy or repeatability. Have you considered a digital approach (A/D, MCU, D/A)?