Triple Envelope Generator is working

Mongo1 · Joined: Aug 11, 2011 Posts: 392 Location: Raleigh NC

Hi All,
Well it's celebration time at Mongo Labs - I just got my new MFOS Triple Envelope Module working!

The module consists of an MFOS ADSR as channel 1, and an MFOS Dual A/R as channels 2 and 3. I've put these all in a single module using a Lexan front panel (spray painted black). The two boards are mounted on one of those handy brackets from the Bridechamber.

There are a few mods I'm making - mainly I've used the NC contacts on the trigger jacks to cascade the trigger from channel 1 to 2 to 3, unless a jack is inserted in 2 or 3 of course. The other thing I'm doing is adding LEDs to show activity. I'm still working on that part for channels 2 and 3. On channel 1 I poked around with my scope until I found something that looked usable - I picked pin 11 of the 4001. I then routed that over to the unused inverter at pin 3 of U3 and then chained that over to the next section of the same chip to reinvert the signal. I used that to drive the LED. Since it CMOS I used one of the new high-efficiency LEDs and a 2K resistor to cut back on the current draw. I ran 12v to the led, and then used the inverter to ground the led. If you're wondering why I inverted it twice, well, er, umm, I screwed up the first time through. The LED was was doing exactly the opposite of what I wanted. Just do to the way things were already wired it was simpler to just chain in the second inverter.

One other thing I've done is used some of the Pot/Switch combinations from small bear electronics for the Attack pot on each channel. On the ADSR channel the switch is used to change to Long times. On the other two channels the switch activates the Loop mode.

The only other mod I'm considering is to change the output structure for the dual A/R so that instead of a simple level pot, I'll have reversible attentuators for each channel so I can flip the signal upside down in addition to changing the level. I need to breadboard something up for that, but if anyone has a suggestion, feel free to toss it my way!

My intent for this thing was to use the ADSR for my main VCA, use channel 2 for filter sweeps, and have the 3rd channel left over for anything else that comes up.

Thanks to Ray for his great design work - this was a blast to put together...

Gary

Front.JPG

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Here's the front panel

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Wiring.JPG

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Here's the insides - two boards - 5000 miles of wire

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