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Low power consumption 24V AC relay

ggaudreau1963

Hi all

 

I am looking to buy/build a low power consumption relay that operates on 24V AC as its signaling supply to drive another relay, this one, consuming a lot of power.

 

Any suggestions?

 

Thank you

 

Guy

  • How low ?

     

    One way would be to use a low power DC relay (reed relay perhaps) and a rectifier and capacitor. Make sure you deal with flyback from the second relay coil or the contacts on the first will only last a very short time.

     

    MK

  • in reply to michaelkellett

    I don't want to use relays as the powerdraw is probbly high,

    Let me explain a little more my issue,

    I built a house a while back and forgot to lay one set of wires for thermostat feed thinking that the thermostat I had its own battery power . After I closed all my walls and finished the house I looked at the thermostats that I had purchased and low and behold they required power.

     

    I had close by each thermostat 2 wires that were not doing anything but they are of small caliber (2 strands of a cat5 cable).  So the 2 strands are suffiicient to feed in one instance 2 thermostats but not much more.

    So each of the thermostats requires the following

         2 wires for 24V AC for power

         2 wires  for output.

     

    I my basement,where the wires all go, I have plenty of low voltage to supply any kind of device that would detect or not detect voltage outputed by the thermostat.  I know thati will need to "drain" builtup power by puling the output of the thermostat to the ground via a resistance butI do not wan tto draw any more power fron the wire that is required.

     

    Hoping that this is a little clearer

     

    Thank you

     

    Guy

  • in reply to ggaudreau1963

    Thermostats generally don't supply power through the output wires.  They typically have a relay that connects or disconnects the two output wires.  It's up to the furnace

    to supply the power that drives its own relays.  I would start by not worrying about the size of the wires and just hook it up to see if it works.  If it doesn't, you would have to know

    what current / voltage (and if it requires AC or DC) the device you want to control requires before you could intelligently decide how to deal with it.

  • in reply to ggaudreau1963

    This link here shows a typical two wire thermostat hook up. Notice that there is not a relay, but a transformer and all of the control is done in the heater valve on the 24V side. Your thermostat simply opens or closes the 24V circuit as needed.

     

    It is funny that you ask this question though, because I have a OMIF-S-124LM that I pulled out of a Microwave oven sitting here on my desk that is a 24VDC/20A @ 125VAC that could work on like 20 or 30 milliamps....Thermostat wire should handle about an amp at 12Volts.....

  • Did you ever consider a latching relay (with some additional safety precautions)?