Compressor auto drain

[GunsOfNavarone]

How exactly do you wire to the compressor so it only comes on for a few seconds when only compressor kicks on?

 

[extropic]

<snip PS - I use a large spring, soft soldered to the outside of a reducing bushing and plugged at the other end , as a kind of muffler/muzzle for the tank drain exhaust. It lives in a bucket of sorts.

Interesting, I think. Is the spring coil-bound, at rest, so the air pressure expands the spring to vent?

Got a picture?