Low Budget Envelope Generator

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Minimal envelope generator module that produces a short percussive envelope from a trigger or gate signal.

This module actually generates a "Decay only" envelope. The trimpot controls the amount of time it takes for the output voltage to decay from +5V peak value to zero. The maximum time is determined by the capacitor. I'm using 100 uF here but if you want a longer decay you can replace this with a larger value. Alternatively, you could add a toggle switch to select different capacitors / decay time ranges.

My total build cost was less than 50 cents because I only paid for the perfboard and header pins. The other parts were all salvaged from trashed electronics but even if you have to buy the whole lot, it shouldn't cost more than a buck or two.

Panelizing this module would only require two (mini) jack ports and a panel-mounted potmeter plus a pinhole for the LED and a range switch if you added more capacitors.

  • 1 × capacitor 330 uF
  • 2 × resistor 220 Ohm
  • 1 × potmeter 10K
  • 1 × diode 1N4007
  • 1 × LED Fiber Optics / Emitters

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  • Revision A

    Mark07/04/2016 at 00:08 0 comments

    The original module has two significant shotcomings: a rather short maximum decay time and no decay at all if the potmeter is turned all the way down.. The first problem is solved by using a larger capacitor (here: 330 uF) and the second issue by putting a 220 Ohm resistor in series with the potmeter to prevent resistance dropping to zero.

    Layout on a small 10x10 hole PCB. The potmeter is not soldered to the circuit board but hooked up with wires so the entire module can be mounted on a panel. I'm using a 1N4007 diode here but any "standard" diode will probably do.


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