The DOD 280 was DOD's first compression pedal made in the late '70s through the '80s. A great sounding compressor, this fairly simple circuit uses an LDR and LED combination (in the form of a VTL5C2) to compress the signal. This one's laid out for on board right angle PCB pots, mounted from the solder side as per usual). I've added polarity protection and power filtering, as well as an input pull down resistor. You can use a VTL5C9 or CLM6000, or a good ol' 1M dark resistance LDR and an LED in heat shrink in place of the original VTL5C2.