Vary voltage in synchrony with other voltage?

This would be approach, attached.



Regards, Dana.

Simple Math leads to simple design.
In = 2 to 5V
Out=1.76V to 0.7V
Gain = (1.76-0.70) / (2 - 5)= 1.06/-3 = -0.35333
Offset= Mean (out-in) = {(1.76+0.7)-(2+5)}/2 = -2.27V
Using a Differential Amplifier with negative gain = -0.3533 and offset of -2.27 using +Vref= 1.82V = (1+Av-)*5V

Choose R values and tolerances to meet your expectations. (design specs)

cupoftea said:

Is the attached the lowest component way for this?

Click to expand...

A single transistor can do the job although to adjust values is a trial-and-error task.
NPN inverts the slope of the incoming signal.
Is your power supply 5V? It can be dropped via zener/led/diode string.

cupoftea said:

Is the attached the lowest component way for this?

Click to expand...

Not quite.
How about with four fewer op amps, six fewer resistors, and only one voltage:

If interested, here is a procedure for determining the component values for the circuit in post #5.
This is basically a variation of the procedure posted in post #3.

• The inverting gain must equal -0.35333 as D. A. calculated in post #3 (the closest value of -0.3549 generated here by the values of R1 and R2).
• This output for a 2V input would then be 2 * -0.3549 = -.7099V (without any added offset)
• Since +2V input should give +1.76V at the output, a positive output offset of (+1.76V + 0.7099V) = +2.47V is thus needed.
• The non-inverting gain at the (+) input is (1+ 0.3549) =1.3549 so a voltage of (+2.47V / 1.3533) = +1.823V is required at the (+) input, which is generated by the voltage divider R3 and R4 from the +5V supply.