$1 DVM as a Digital Input Display
My 5V circuit has a potentiometer to adjust a timing delay and I wanted to add a digital display for precise calibration. I realized that 0-5 seconds could be displayed as 0-5 volts on a dollar DVM, so I just used the pot as a 5V voltage divider and connected the DVM to the wiper. (This requires a 3-wire DVM, since a 2-wire unit won't work below ~3V.) Micro reads the voltage via ADC and the code converts into seconds.
If desired, the input range could be limited or shifted by adding one or more fixed resistor(s) in series with the potentiometer. This would also reduce the sensitivity of the pot adjustment and help stabilize that last flickering digit on the DVM. I used a $1 Powerbank for my 5V supply. One advantage to leaving the upper limit at 5V is that I can use the DVM & pot to check for full 5.0 V output. Less than 5V indicates a low 18650 battery in the Powerbank and time to recharge.