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Eurorack Voltage Detector

 This is a Eurorack Voltage Detector module design. The idea for this comes from combining two previous modules I designed; the Level Display module and the recent Comparator module. This module uses op-amps in the comparator configuration to compare a signal against several reference voltages and display the output of the comparison on an LED. 

The voltage levels compared against are approximately: ±9.8V, ±4.9V, ±3.2V, ±0.9V

The module has two independent sets of comparators so two different signals can be plugged in at the same time. 

The main use for this in my rig is when interfacing modules from various manufacturer's the acceptable input voltages aren't always the same and it's annoying to have to look that up for each module. I usually remember to add the output voltage range in the engraving on my panels so there's no guess work, others don't usually do that. This module will let me quickly see what voltage a signal is at and attenuate/amplify it as needed before plugging it into something else. The Level Display module, one of the first I made for myself, is better for AC (audio) signals and designed for showing the level in more common decibels like in most audio amplifiers. It also used an Arduino Pro, this module however can be used for AC and DC signals and only uses op-amps.

I started the design with some simulations and a prototype on the breadboard (only a few voltages on the breadboard version though, not the entire circuit).

After that I had two PCBs made and designed the front panel.

Overall the design has worked as planned. There may be additional uses for the front panel and the 2.7k LED resistors use a lot of current but that's easily tweaked with different values.

Module Width: 3 HP
+12V Current: 45mA LEDs off, 155mA LEDs on w/ 2.7k resistors
-12V Current: 45mA LEDs off, 153mA LEDs on w/ 2.7k resistors

Design Files: voltage_detector