power a 120v relay from a triac timer?

Thread Starter

lorenzop

Joined Jul 2, 2009
12
I have a brinks in wall timer from walmart hooked up to my front porch light. it works ok, but it's in-line, and uses a triac for switching. I also have it wired to out door outlets in the roof to put christmas light on that same timer. right next to that outlet is another outlet with a photo sensor hooked up to it to plug in a bug zapper. the photo sensor has it's own neutral leg for power, and uses a relay for switching. what I want to do is use a 120v relay with the coil plugged into the timer outlet, then the contacts of the relay hooked to the photo sensor and to a plug for the bug zapper. the timer turns off at 2am. I want the bug zapper to only be on between 2am and sunrise. same problem as using a cfl on a triac, it flickers. I plug my relay into the outlet and it flickers too. how can I fix this? I'd have a problem with it hooked up either way, the bug zapper has a fluorescent bulb in it and flickers when plugged into the timer. how can I power either the relay or the bug zapper from the wall timer?
 

Wendy

Joined Mar 24, 2008
23,415
You could use a relay, or your could use a SSR. The timer triac is exactly like a relay in it's application, but is probably limited in current. You just use it like a switch for a larger relay.
 

Thread Starter

lorenzop

Joined Jul 2, 2009
12
You could use a relay, or your could use a SSR. The timer triac is exactly like a relay in it's application, but is probably limited in current. You just use it like a switch for a larger relay.

yeah, I'm trying to use a relay with a 120v coil rating. you know how compact fluorescents flicker if you put them on a light dimmer? that's the same thing that's happening with my relay on the timer. it just keeps clicking on and off. it works perfectly if I add an incandescent bulb to the circuit, but that defeats the purpose. I want to be able to turn off the porch light and have the relay still working right.

I think the problem might be that the relay restricts to much current from the timmer, and the triac shuts down when the ac voltage is near 0v. I think the right size resistor and high voltage capacitor in series, hooked up at the relay's coil, would allow a little more current past the relay. enough for the timer to work right. but I don't know if this is safe, or what values to use.
 

Wendy

Joined Mar 24, 2008
23,415
Just connect the output of the timer to the relay coil, and then use the relay contacts as a conventional switch. This project has some danger to it, being you are dealing with house currents, so put this sucker in a box (and be careful). I get the feeling you don't know too much about house current, it may be better and cheaper to buy a different timer, one with a better switching arrangment. The several I've bought over the years tend to use light weight relays.
 

Thread Starter

lorenzop

Joined Jul 2, 2009
12
Just connect the output of the timer to the relay coil, and then use the relay contacts as a conventional switch. This project has some danger to it, being you are dealing with house currents, so put this sucker in a box (and be careful). I get the feeling you don't know too much about house current, it may be better and cheaper to buy a different timer, one with a better switching arrangment. The several I've bought over the years tend to use light weight relays.

I'd prefer one with a small relay in it, but it's tough to tell just from looking at the package or even a manual. don't worry, I have plenty of experience as an electrician and a programmer. I don't think anyone understands my problem yet. I plug the relay's coil into the timer outlet, but it doesn't draw enough power to keep the triac powered up inside the timer. if I also plug in a normal light bulb into the same circuit as the relay then it draws more power and works fine, but I want it to work without having a light bulb on. the relay just keeps clicking. what I think I need is a resistor and capacitor in series to simulate a light bulb but not put off any light. just to pull a few extra milliamps and allow the timer to work right. I don't know what values to use or if it would work as imagined, so I was seeking advice from someone with experience. basically, how do you simulate a light bulb on a light dimmer without the light.
 
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