I understand that there is a small circuit board keeping time and turning power and and off to the lights (or something like that). But what is physically moving on the circuit board, to keep track of the time?
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A crystal oscillator, typically.
It is surprisingly simple once you know how it works. You know how a wine glass makes a very pure tone if you tap it? Notice it’s always the exact same tone too. The frequency it resonates at is determined by it’s shape and the material.
Now imagine a slightly smaller glass. It’s pretty easy to predict that it’s going sound a little higher in tone, right? Because the resonance frequency is higher.
Now let’s keep at it and keep shrinking it until it’s smaller than a grain of salt. It’s a little hard to tap now, of course… But what if we could tap it with electricity though? Enter piezoelectric materials! They also have the benefit of not only doing a little “jump” when you apply electricity, but they even send a little electric pulse *back* after their little jump.
So you just poke it at the same rate that it pokes back and you’ve got a clock frequency going.
Keeping track of time then is just a simple matter of counting cycles of the clock.
Usually for something that’s not crazy percise (like holiday lights) there’s an electronic latch with two inputs.
If one input is higher than the other power can flow to the lights, otherwise it can’t.
There’s a small battery like component called a capacitor. It’s given a small power supply that slowly charges it up. Eventually it has enough power to flip the latch. Then with the same latch flipping, the capacitor is given a path that it can slowly drain out into. When the capacitor charge dips too low again, it flips the latch back.
At least, that’s the ELI5 version.
Edit: more junk about this…
Nothing is actually moving, it’s just changes in voltages and polarizing materials by use of electricity to create and restrict pathways in a circuit.
Unless it’s a much older style ticker. There’s a method of binding two different metals together into a prong or spring that bends when it gets too hot, and clicks into a different shape.
In one shape, it’s connecting a pathway for electricity to flow. And since electricity is flowing through it, it gets hot. Eventually it gets too hot, the metals expand, and the prong pops into a new shape, like a dent in a soda can will pop under pressure. The new shape isn’t connecting a path, electricity isn’t flowing through it, and it cools down. Eventually popping back again to reconnect the pathway.
This is where the sound of a vehicle turn signal originally came from. That prog in the circuit popping back and forth.
You’ve got people talking about quartz timers and such here. While that is a way of doing things, it would usually only be for really fancy lights because it’s more complex and isn’t necessary to create some simple blinking effects.
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