Quad AR EG

I still have yet to label the controls!

This is one of my favorites. It is based on 2x MFOS dual AR EG circuit boards, so I get 4 envelopes total.

Each envelope "channel" is arranged in a column

The top green in the main GATE input. The next green below is a sort of auxillary GATE input, but I should redesign/repurpose it. It didn't quite do what I wanted it to do.

The blue jacks are the ENVELOPE OUTS.

The orange jacks are GATE OUTS from a comparator circuit at the ENV outs.

On the MFOS suggested wiring, the GATE OUT is switched to the input. Mine is patchable for more flexibility. The obvious move is to chain the 4 together so that they trigger in sequence. That is one idea. You can also trigger other modules with the GATE OUT.

The first mini toggle selects between TRIG or GATE mode. TRIG means the envelope will fire through the entire ATTACK and RELEASE times after receiving a TRIG.

GATE mode means you get ASR type envelopes, sustaining as long as you hold the GATE high.

You can also abruptly end the envelope, unlike the TRIG which goes through the whole thing.

The second mini toggle selects the range of envelope times from SHORT MED or LONG.

The first control is a bipolar CV output. Centered is 0 or OFF. Turning CW increases the envelopes CV voltage up to a maximum of +10V. Turning CCW decreases the envelopes CV voltage down to minimum of -10V. The MFOS design is only for 0 to +10. I added a variable sign changer circuit to get -10 to +10.

Next control is attack time and last control is release time. Fully CCW is fast and fully CW is slow.

In the rear shot you can see the daughterboard that allows all of the outputs to be bipolar. This takes only 1 op amp per output to accomplish, so a TL074 quad package takes care of all of them. This was an early experiment with molex connectors from Small Bear Electronics for easy disassembly, if needed.