hai bro i want make digital potentiometer use similiar part and design. the number of potentiometer show in 7 segmen but not with microprocessor. if somebody know about this please share with me.
tanx
It surely can work with discrete logic devices, e. g. CD4000 or 74HC family, but the part count must be expected much higher than with a microprocessor, that would allow true single chip designs. But it had been the usual way some decades ago.
I don't know what you're going to use your digital potmeter for. But have you considered if it will work with a variable current sink?
Then you can have an arbitrary number of bits in that is used to control the output current.
You need:
* a simple DA converter (a handful of resistors - R + 2R)
* Opamp
* BJT transistor and a resistor (low value) where voltage over thhis resistor makes the current.
About any opamp will work.
Beside that, you use just regular resistors and buffer. Good choice could be R=10kΩ
You're free to decide if 2R would be two resistors in serie or if R would be two in parallel. You won't get combination R and 2R out of the usual E12 serie.