Super tiny OLED 0-30V voltmeter

This tiny voltmeter consists of a 0.5" white OLED screen (88 x 48 resolution) and a driver PCB, connected by a flat ribbon cable. You can simply fold the OLED screen over and stick it to the back of the driver PCB (the driver PCB is pre-taped, just peel off the backing paper) to make a tiny voltmeter measuring just 18 x 9mm (not including mounting lugs, which can be snapped off if not needed).

Supply voltage range is 3.5-30V DC and measuring range is 0-30V DC. The supply and measured voltage share the same ground, and the meter can be used in 2-wire or 3-wire config (for 2-wire, just solder the V and V+ pads together).

The meter features a 12-bit high-precision ADC and displays the voltage to 3 digits (decimal point shifts automatically, as you would expect). You can choose to hide the little V symbol by bridging the "A" solder pad pair, and you can also adjust the refresh rate, the default is 5Hz but you can boost this to 10Hz by bridging the "B" pair of solder pads.

Operating current is less than 20mA and accuracy is around 0.7%.