Sensor to trip with presence of voltage

Thread Starter

caddrawer

Joined Apr 10, 2021
4
Hello all,

I have a motion sensor light that I tried adding a relay to to drive the rest of the lights on the front of my house. The motion light outputs 110VDC to drive the LEDs, but there is not enough amperage to drive a cube relay with the LED lights. Is there a way I could sense the change in voltage that I could then drive a relay? I'm more of a mechanical guy, but do a lot of relay and small plc design to drive equipment. Thanks for any suggestions.
 

MaxHeadRoom

Joined Jul 18, 2013
23,639
Sounds like you are trying to operate a relay with the motion sensor, you need to add a Mosfet or similar, post the details of the sensor and any LV supply that is present.
 

Thread Starter

caddrawer

Joined Apr 10, 2021
4
Maybe I'm doing this wrong, but I'm picking up the 110VDC off of the wires going to the light's and not using the motion sensor. I figured that when the motion sensor turned on the lights I could pull a little current off the LED lights to drive a relay, but the lights won't even turn on then. I unplug the relay and it works find, so the relay is pulling too much amperage and I need to figure out a different way to drive my other lights.
 

wayneh

Joined Sep 9, 2010
17,153
Maybe I'm doing this wrong, but I'm picking up the 110VDC off of the wires going to the light's and not using the motion sensor. I figured that when the motion sensor turned on the lights I could pull a little current off the LED lights to drive a relay, but the lights won't even turn on then. I unplug the relay and it works find, so the relay is pulling too much amperage and I need to figure out a different way to drive my other lights.
As @MaxHeadRoom suggested, you probably need a MOSFET switch instead of a relay. But it could be that a different relay or a different hookup would do the job. No one can tell without more details.

It seems to me that if the LEDs make any significant light, there should be enough juice to also trigger a relay. But it needs two be a low-coil-current relay.
 

Alec_t

Joined Sep 17, 2013
12,210
What is the spec of the relay? Does it have a 110V DC rated coil? What coil current is required for it to pull in?
 

Thread Starter

caddrawer

Joined Apr 10, 2021
4
Thanks for the replies, The relay I was trying to drive was a Dayton 5YR09 which has a rating of 1.2W on the coil. As mentioned, I'm a mechanical guy, but I have taken a schematic and can breadboard a circuit. Just don't ask me to design it. I know the LED's in the light are driven at 110VDC as I did use my multimeter to determine it. But I don't know how much amperage is used or available. I found a .4W relay that I might try. As for a mosfet, unless someone can tell me more of what I would need to do with one, I would be at a loss.
 

BobTPH

Joined Jun 5, 2013
3,682
You have to match the voltage of the relay coil to the driver voltage. Watts does not tell us what the voltage is. In this case, you need a 110 VDC relay, which might be hard to find. Do not use a 110V AC relay.

Bob
 

Thread Starter

caddrawer

Joined Apr 10, 2021
4
You have to match the voltage of the relay coil to the driver voltage. Watts does not tell us what the voltage is. In this case, you need a 110 VDC relay, which might be hard to find. Do not use a 110V AC relay.

Bob
The Dayton 5YR09 is a 110VDC relay.
 
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