OutletTimer 2 - using a mechanical relay

Описание: It turns out the solid state relay I chose had a small leakage current which meant it did not turn completely off. Since the air pump that sparked this project still drew some current and hummed when the SSR was off, I got up to speed on mechanical relays and now the pump turns completely off.

I've learned that solid state relays are a little tricky, they come in DC and AC specific versions, and at least the one I have does not turn completely off.

The mechanical relay requires some additional circuitry, and this is a great video that helped me understand usage of the transistor I ended up using:
   • Tutorial: How to design a transistor circu...