Instructables

Is there a relay that uses a 110v trigger for a 12v output?

I know that this is probably the most backwards way to do things (and yes, I know, probably extremely stupid [but I'm also new to relays..]) , but I am in the process of trying to make a heated platform for my RepRap (I have gen 6, thus the reason for this). I have a PID controller, and I have the board running off an ATX power supply. So, what I would like to know if there is a relay that can use the 110v the PID controller to turn on/off the power from the ATX to the heat bed. 
Thanks in advance! 

iceng1 year ago
Most PIDs Iv used have a built in SPDT single pole double throw  set of contacts
that means ....  oh just look at the pic.

The contacts are able to handle your 12v requirement.

A
SPDTrelay.gif
I was thinking the same - but those heaters have quite a high current rating.
Then ,
PIDSPSTrelay.GIF
DoctorWoo (author)  iceng1 year ago
What I end up actually doing was treating the PID's SPDT as an actually SPDT lever, so the entire need for a relay is a mute point. I actually hooked it up as a test, and it works beautifully.
Just be careful that you don't exceed the current rating of that internal contact.
DoctorWoo (author)  steveastrouk1 year ago
That was the first thing I check. I 'm only pushing about 5a through a 10a limit. But thank you for pointing that out! Just with my track record on this question, it's a miracle I remembered to check that.
I wonder do you heat the RepRap bed just when starting or throughout the process ?
DoctorWoo (author)  iceng1 year ago
I've heard mixed reviews on that. I'm still calibrating it, so the finer details (such as when to heat the bed and turn it off) are still a mystery to me. For the most part, I've read that you want it about 110, and it can stay on through the whole print. However, some part do need to have the bed turned off at a certain point to avoid it "melting" on itself, and avoid warping.
DoctorWoo (author)  iceng1 year ago
Oh man...I think with that answer this is official the dumbest question I have ever asked. I hadn't thought to treat the switch of the PID as...well...a switch. For some stupid reason, I thought the 110v label for the heat portion would be the need voltage for it...anyways, thank you very much!!
And as for your question with RepRap, I bought it eBay piece by piece. The main guts for it came from the MakerBot ebay store (which, at the time, was cheaper then makerfarm itself)
iceng iceng1 year ago
BTW where did you get your RepRap ?

I'm looking to get my own soon.
Yes, of course. Buy a 110V coil relay !

But post some more information on your PID controller. I'm surprised it doesn't have dry contacts.
DoctorWoo (author)  steveastrouk1 year ago
And, again, I feel like an idiot.

But here is the PID controller I have: http://www.ebay.com/itm/Digital-STC-1000-All-Purpose-Temperature-Controller-Thermostat-Aquarium-w-Sensor-/140756919030?pt=LH_DefaultDomain_0&hash=item20c5c422f6