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Playing with Power

I just ran across some Solid State Relays cheap on Digi-Key ($12 each), so I bought myself four of them.

For those of you who don't know, a Solid State Relay (SSR) is a nice little component that lets you take a low voltage, low current control line — from a micro-controller, for example — and use it to switch a higher voltage, high current line. In this case, I can use a 5 Volt DC output from my Teensy++ controller (with only ~10mA draw), and switch up to a 250 Volt, 25 Amp AC line. This means it's capable of switching standard 120V AC US wall power with lots of capacity to spare.

Hooking it up was ultra-easy, as I cannibalized a power strip to get sockets and wall plug. I just interrupted the hot line with the relay, hooked the SSR inputs up to my Teensy++ micro-controller, and moments later I was having the Teensy switching a light on and off. Since the SSR is so beefy, I could hook power tools and AC motors up to it if I wanted to.

What I plan to do with this is to use one of the SSRs to let my Fabber unit's electronics switch a high-current AC heater pad on and off, so my build platform can have a reasonable warm-up time. I also have vague plans for having a Christmas light display next year that can switch a number of light strands on and off in a synchronized way.


( 2 comments — Leave a comment )
Jan. 9th, 2010 06:58 pm (UTC)
There was a little used parts store near where I worked that cannibalized a lot if equipment (especially old photocopiers) for bitss. He was selling 2A versions of those solid state relays for $2 each. I bought all he had. They were great for doing computer controlled lighting. They worked great when driven off a couple of centronics printer ports.
(Deleted comment)
( 2 comments — Leave a comment )

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  • 17 Oct 2011, 19:18
    Clever! ^_^
  • 7 Oct 2011, 08:38
    Was each link made from two pieces, or was there fill material inside that you removed? I'm having trouble seeing how to print these in a makerbot-compatible way (though I could just be overlooking…
  • 5 Oct 2011, 22:40
    Nah. It'd just take a dissolvable support material and higher resolution. There are commercial 3d printers out there that can print ball bearing assemblies in one pass, fully assembled.
  • 5 Oct 2011, 18:46
    Nice! ^_^ I was going to be flabbergasted if you were actually able to print it as a unit, but I guess that would take antigravity.
  • 5 Oct 2011, 18:19
    I printed each piece individually and assembled them after some cleanup. I did print four segments at a time, though, unattached, in a 2x2 grid.
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