1
\$\begingroup\$

What would be the "correct" way to replace an analogue potentiometer with a microcontroller controlled digitalpotentiometer, when the require voltage is higher than what the chip can support?

In more detail: If I want to replace an analogue potentiometer for a 10 Vdc signal line with a digital potentiometer that only supports up to about 5 Vdc, what is the best way to achieve this ?

Is it a simple 5Vdc digital potentiometer with an opamp before/after to adjust the voltage accordingly ? Or...?

Please be specific - circuit diagrams for achieving this will be appreiciated. Basically, replace a basic manual potentiometer with a digital one, for a different voltage level.

\$\endgroup\$
  • \$\begingroup\$ Are you trying to adjust a voltage, or a resistance? \$\endgroup\$ – evildemonic Mar 29 at 21:58
  • \$\begingroup\$ I believe it is the voltage. A signal line to control a motor (signal - not in-line) \$\endgroup\$ – user216989 Mar 29 at 22:01
  • \$\begingroup\$ Please be specific for what functional purpose do you want to replace the potentiometer. If it is used by the original circuitry to charge-discharge some voltage (like in many 555 circuits) then simple voltage translation (or DAC) won't do the job. \$\endgroup\$ – Ale..chenski Mar 29 at 23:19
0
\$\begingroup\$

Without knowing more about your circuit: I would use a DAC (Digital to Analog Converter). If you can find a DAC that runs off 10V great, otherwise just use a 5V DAC and put an opamp with a gain of 2 in front of it (or even a 3.3V DAC and a gain of 3).

Your microcontroller will send a serial command to the DAC to set its output voltage.

This is what a non-inverting opamp circuit with a gain of 2 could look like:

schematic

simulate this circuit – Schematic created using CircuitLab

\$\endgroup\$
  • \$\begingroup\$ What is the difference between a digital potentiometer and a DAC really ? Both would adjust the voltage according to input signal ? Not really that much into electronics - can you provide some references of how to achieve this ? In particular the opamp circuit ? :) \$\endgroup\$ – user216989 Mar 29 at 22:09
  • \$\begingroup\$ A digital potentiometer is a device that takes a digital signal and varies the resistance of its output. A DAC takes a digital signal and outputs a specified voltage. \$\endgroup\$ – evildemonic Mar 29 at 22:10
  • \$\begingroup\$ So if a motor is controlled by the voltage (signal line adjusted by a manual potentiometer) a DAC would really achieve the same thing? \$\endgroup\$ – user216989 Mar 29 at 22:14
  • \$\begingroup\$ Sure. You should see how much current this voltage signal input draws to make sure you can supply it, but yes. \$\endgroup\$ – evildemonic Mar 29 at 22:18
  • \$\begingroup\$ So if voltage-controller, all I need to replace a "manual potentiometer", besides the microcontroller, is 2 resistors and an opamp ? :) \$\endgroup\$ – user216989 Mar 29 at 22:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.