I built this noisegate on a piece of perfboard in the early 90s and it performed 'ok', for what I recall.
Just today, I've put the schematic in Eagle and made a layout for it, but I haven't tested nor verified this layout yet (!!!). The original called for a symmetric power supply (+/-9 ~ +/-15V), I made it with a Vref so only +9V is needed. It's a quicky so there's quite a bit of improvement possible, and not only layout-wise: as-is it has an unbuffered audio-path so the obvious first improvement would be to add this.
A few more notes:
* the 'off' pad (PAD1 in the schematic) can be switched to GND to turn the unit off (if no true-bypass is used)
* R7 determines the speed, substitute with a pot or a pot in series with 10k or so for a variable setting
* D2 was originally a germanium (AA119)
* I didn't have a BF256 footprint on hand so I used a 2n5457. Check the pinout before soldering! Actually, the original article mentioned that there are different pinouts of the BF256 around, depending on manufacturer...
Attached are the schematic (inline) and the eagle project, the zip includes images for the pcb and the parts placement.
