mENG Qi - Dual Passive Low Pass Gate

I've been looking for some Buchla inspired LPG modules lately for my performance case and came across one by Meng Qi.


There were no build notes with this but its pretty simple so was easy to figure out.


These are not official build notes... just my record keeping in case of future trouble shooting.

 Make sure you get the LED orientation right.

So what exactly is a low pass gate?
"A lowpass gate is essentially a low pass VCF configured to behave like a VCA. ... The Buchla design used a vactrol to process the control voltage input; the vactrol had certain non-linearities which made the lowpass gate a good module for imitating some tuned percussion sounds.(wikipedia)


The Module is only 2HP width.
The gates are I think 6dB slope ... that is single pole/


What surprises me about this module is just how good it sounds ........and all without any power .
A single trigger pulse 


Orientation of vactrol ... match the dots.


a REALLY simple build ... great as a starter SMD project.