This is a double version of my Voltmeter build for my 15V Banan System, adapted for Eurorack and 12V. The original circuitry of this module was developed by Ray Wilson of MFOS. It was part of his Multi-Function Module. I have changed some resistor values to use it with low current LED.
The LED voltage level meter gives you a graphical idea of where the voltage level you like to use to modulate your filter or VCA is. This circuit lights the LED in real time giving you a rough idea of the voltage level you are looking for. This is very useful when you want to move a CV from bipolar to only positive values.
Specs and features
- Three voltage ranges (+/-1V, +/-5V, +/-10V)
- Realtime LED display
- Runs on +/-15V and +/-12V
- Power consumption below 35mA each rail
IC1A is used for input buffering. IC2A and IC2B and associated components on the control board build the range selection circuitry. The heart of the circuit is the group of comparators build with IC1x, IC2x and IC3x on the main board(s). The left side is used to measure the positive voltage, the right side for the negative voltage. LED18 (control board) is the "near ground" indicator. IC3C and IC3D build a window comparator. For a more detailed description please refer to the original source at Ray Wilson's Site MFOS (Multi-Function Module).
- With the range switch in mid position (1V range) adjust TR_1(TR_2) for 1V at pin1 of IC2A(IC3A).
- You need two main boards. Mount the power connector only on one.
DownloadDouble Volts control board documentation download
Double Volts control board Gerber files download
Double Volts main board documentation download
Double Volts main board Gerber files download
Double Volts *.fpd file