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Test Fixture and Calibration - Eurorack MIDI to 16x16 CV Gate Module

This design, along with its firmware and scripts were made so that the CVs of the  Eurorack MIDI to 16x16 CV Gate Module  (MIDI_16Gx16CV) could be calibrated and the other functions tested. That module is difficult to validate after assembly and had some teething issues that I wasn't able to figure out without a way to measure all of the CVs across a wide range of outputs. I tried to make measurements of the module manually on the first few I made but the results weren't amazing. The initial intent was for the main board of the MIDI_16Gx16CV to plug directly into the test fixture. The test fixture has connector sockets aligned with the main board. Unfortunately I made a classic mistake mirroring the design so I had to create some cables to connect the test fixture to the DUTs. In the end that worked out okay, I'm not sure it would have worked if the headers had been correct (for other reasons).  The test fixture uses an Arduino Pro Mini. To get enough I/O to read the gates
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Eurorack Envelope Generator ADSR AS3310 v1 and v1.1

Here's an 8HP envelope generator based on the AS3310 chip. It's very similar to the  Polyphonic/Quad ADSR EG Module , because that was the starting point. I found myself needing additional ADSRs and that was the easy way to make one. To fit in 8 HP the circuit is split onto to PCBs. As with all of my designs, the signals in/out are 0-10V. The trigger input and switch is a new input on this (compared to the Quad ASDR). It appears to work; however, I haven't focused on testing it. Version one of the PCB had the out/release pins reversed on a header so the images below show rework for that. I had to rework and reorder another design so I quickly made a v1.1 for this at the same time and that corrects this issue. v1.0 PCBs in these photos require rework, but v1.1 is otherwise identical.          Module Width: 8 HP +12V Current: 26mA -12V Current: 26mA Design Files:  envelope_generator_AS3310 Schematic:  envelope_generator_AS3310_v1.1.pdf BOM:  envelope_generator_v1.1_bom This w

Eurorack VCO Module - AS3340 v2.1

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Eurorack Voltage Detector

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Eurorack Comparator Module

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Eurorack Analog Switch Module

This design comes from a long term project/idea to make a noise gate for Eurorack. I've attempted several designs for a noise gate over the last year but haven't been happy with the result (yet). In the latest attempt I used an analog switch and a comparator and had some success. I decided that those two parts of the noise gate would be fine as individual modules so that's where this came from. It's really a very simple module, there's a buffered input and ouput and a gate input to turn the switch on or off. When it's on the audio or whatever input signal is passed through to the output. The schematic calls out the DG418LDJ (normally open) analog switch. The DG417 should work as well for a normally closed version. The gate circuit is using a few generic NPN transistors to turn whatever the gate input is into a sharp 5V logic signal for the analog switch. There's a simulation here . Of course the design started on the bread board. Then I designed and ordered

Eurorack VCO Module - AS3340

Update 2023-02-18: There's a new version of this design: v2.1 I don't consider this design done; but, I've gotta start writing it down because I'm carrying too much diagnostic info in my head regarding this thing. One of the early kit's I built was this AI011 VCO . Despite the website saying it uses a Curtis chip (CEM3340) mine came with a clone AS3340A. At the time I didn't know anything about either chip, I just wanted a VCO to build and play with. Overall it is a fine VCO, it sticks to the datasheet's circuit for trimming. I also built four Befaco Even VCO s to use with the polyphonic envelop generator . I was initially on the fence about building my own, but I eventually decided it would be a nice accomplishment to do an entire signal chain from keyboard to output all of my own designs and an oscillator was gonna be necessary. So I bought some AS3340's from Electric Druid and set about making my own design. The AS3340 has a triangle, falling sawtoot