I have a control voltage at one point in a circuit which I need to duplicate at various other points (3 or 4, if I remember correctly). I'd like to use one potentiometer to control these voltages, so I need to "duplicate" the control voltage at the points I need it in. The problem is that I need to raise and lower voltages in the circuit by the control values, so I can't just use a buffer amp--it needs to be a floating source. Essentially I'm looking to build something like:
The output resistance isn't very important, as in all cases the next input stage is an op amp, and \$V_x\$ is no more than 3-5 volts. How would I go about building something like this? I know I could convert the voltage to AC, use two transformers, and then filter the output, but I'd like to keep this DC if possible.