Need Help with a relay Circuit

Format _C:

Format _C:

2[H]4U
Joined
Jun 12, 2001
Messages
3,886
I have frequent power outages (I live in a rural area outside a city) I have a CyberPower UPS but what I want to do is have a lamp come on if I lose power and then go off when power restores. I don't know alot about electronics but I think what I want to do is simple right? Here's what I think I need to do but again I have little electronics knowledge I have a extra 5VDC/12VDC transformer that will be plugged into the surge only (When the power goes out those outlets loose power) and then a relay comes in to switch on the lamp (9W CFL) when the the DC 5V or 12V goes dead the relay will switch on the lamp which will get power from the battery backup outlets. I just need help with what kind of relay to get and how to wire the high and low-Voltage parts
Thanks
 
cant you set up the UPS to beep when the power goes off? most of the ones i ever used do that
 
if its a 12vdc light, get a relay rated for 12vdc and 500ma or whatever the transformer says, again, this will work perfectly with automotive relays since cars are all 12vdc.

get two 12vdc transformers, plug one into the strip, one into the battery backup, wire the one into the battery as normally open, and the other should wire into the control side of the relay.

as for the relay, you'll want something like a single pole double throw relay.
 
The UPS does beep when the power goes off. The last power outage I had was at night (Luckily the computer was on so I was able to see to plug in the lamp) and where I live at night it is very dark with out the glow of the Metal Halide Street lamps :). I have a 120VAC CFL any a ton of extra lamp parts (I used to fix lamps) so I am sure I could put something together (I will remember to insulate all of the live parts
 
if its a 120vac lamp, get a relay rated for 120vac and wire it through the normally open part of the relay (the terminals will be NC, NO, and C, put the neutral leg through C, and the hot leg through NO), then wire the 12vdc brick through the control side of the relay.

when the 12vdc is supplying power, the relay will stay open. when your power goes out, the 12vdc side will drop power, closing the relay turning on your lamp powered by your UPS.

to control 120vac circuits using 12vdc we use relays called mr-201c's... but these are like $26 a peice becuase they're ul listed for fire and we use them in industrial/commercial applications. there's gonna be something similiar if not identical that's cheaper.
 
You'll need SPDT (Single Pole Dual Throw) relay with 12V coil. (often there are variants with 5V and 24V coils)
Also contact needs to be able to handle needed current at 120VAC.

plot said:
wire it through the normally open part of the relay
Click to expand...
That way lamp works entirely opposite of wanted: It shuts down with power because normally open contact is open in relay's normal/non-controlled state.
Contact needs to be closed when relay doesn't get control and open in active state.
 
You must log in or register to reply here.
Back
Top