Turning something higher voltage on

How do I use the arduino to turn something on with much higher voltage. For example I have a different power supply, hooked to a 100W motor, with correct voltage and such, how do I use the arduino to turn that on? Please don’t hurt on me, I am a noob.


that should give you a pretty good sense of how to control it. If you need to sense what power is going to the load, I highly recommend the HCPL-7520 to get you isolated and operational. Link for the part is found here: http://octopart.com/info/Avago/HCPL-7520-300E

Also, if you're trying to do control of brushless motors then you're in need of a control method. I highly recommend the http://www.sparkfun.com/commerce/product_info.php?products_id=9107

If you run with that part then I've got a tutorial up on my blog on how to use it for motor control: http://thecodebender.com/journal/2009/2/21/we-just-cant-leave-things-well-enough-alone.html

I really appreciate this. Thank you, this is exactly what I was looking for.

For controlling 120-240 VAC, 15-60A line current, you have available Solid State Relays which are basically super-sized optocouplers, controllable by 5VDC input.

OPTEK OSSRDOOO2A Input: 4-32vDC Load: 15A 250VAC


Cheaper than a solid-state relay for switching 120VAC is a Triac, controlled by an optically isolated mini-triac. Something like a Fairchild MOC3032. The datasheet for that part has some good example circuits.

I've used those Optek ones at work to switch a huge solenoid and a motor for a Arcade punching machine, which is on a helluva lot and the people like to use it for hours.

They're real workhorses them things.

Using a Triac and a Opto-coupled Diac trigger definitely would be cheaper. You get experience building an SSR from scratch. Be sure that you have it properly heat-sinked and that everything is properly insulated.Putting a fuse in there isn't a bad idea either.

I usually suggest the SSR because it's easier to implement safely. $12.50 is very inexpensive if you're not experienced with building safe line voltage control circuits.