BlikenLichten

We bought timers for our Christmas lights this year. It let us have them on while we were away, and probably saved some money since we didn't forget and leave them on all night.

The timers we got are digital (I wanted grounded outlets, and digital was the only way we could find a time with grounded outlets.

Of course, we got it home and I had to take it apart; I had to know how it worked.

Do you recognize anything thing? Here, I'll give you a hint:

DC From AC Without a Transformer

The timer is made up of two boards, a power/switch board (left) and a clock board (right). The timer is powered by the rectifier/capacitor circuit in the lower left through the Yellow-Red wires, running to the clock. The clock has a battery (green, upper right), a photo sensor (middle far right, "dusk") and a quartz crystal (middle right). The clock signals a relay (black box, middle left) through a trigger circuit to turn the outlets on and off. I'm not precisely sure how that circuit works (didn't try to lift out that board). Plausibly, the clock opens the transistor (middle left, beside the relay), which applies partial rectified power using the diode and capacitor to the relay's coil. (The relay doesn't work when the timer is unplugged).

I'm surprised at how much of this timer is air and hand assembled discrete components.