I need advice on which RELAY to use in my circuit.

Discussion in 'General Electronics Chat' started by Ishan Perusinghe, Jun 24, 2015.

  1. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    Im trying to build this lighting circuit for a light feature Iam building. Diagram attached. Let me give a quick overview . There are two circuits . Circuit 1 is led lighting strip circuit and Circuit 2 is a mains light circuit. What I would like to happen is when the wall dimmer switch is turned on in circuit 2, the completed circuit 2 will activate the relay in circuit 1. This will complete circuit 1. When the wall dimmer switch is powered off in circuit 2 . Then circuit 1 will deactivate also as the relay switching leg 3 loses power. See diagram attached.

    This is wall dimmer I am using.

    ttp://pages.ebay.com/link/?nav=item.view&alt=web&id=251655906936&globalID=EBAY-GB

    Can you guys give me any advice on is what type of relay can be used to do this and if my circuit is sound

    IMG_1769s.JPG
     
  2. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    forgot to say thank you for any help :)
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    the relay will be switched by the output of the dimmer? Do I understand your drawing correctly in this case?
    That may be a problem. Relays that work from line voltage are common, but a dimmer can lower thst voltage into a range where relay operation is not possible. You need to insure your relay coil can receive full line voltage when you operate it. Variable voltage is not a proper drive for a relay.
     
  4. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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  5. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    is there something else I could use instead of a relay then . all the componnet needs to do is switch on circuit 2 with current is detected on the 3rd trigger pin.
     
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    if the voltage can vary so widely (24-240 VAC) then I am not sure there is a "simple" solution. Let us wait for more members to view this thread and see what answers they can provide.
     
  7. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    ok thanks for your input . Im pretty much a noob to electronics circuits.
     
  8. dl324

    Distinguished Member

    Mar 30, 2015
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    I'd suggest using an optoisolator to drive the relay and have the relay powered from circuit 1 240VAC. You could use a zener and resistor(s) to limit the maximum voltage across the opto LED.

    Don't know if the ToS was changed to allow transformerless line powered posts...
     
  9. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    Ok I have not heard of an optoisolator or optocoupler. But i found a video On youtube that explained it well.

    I think this is heading in the right direction as the optocoupler can trigger circuit 1 powered on 240VAC. But I will need to find a relay with an Optocoupler built in . The one below does what I want for circuit 1 but doesnt take in 240 VAC for circuit 2. It requires a DC .

    http://www.ebay.co.uk/itm/1-Channel...t=LH_DefaultDomain_3&var=&hash=item3f492ef783
     
  10. #12

    Expert

    Nov 30, 2010
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    You can't install a mechanical relay rated for (much) less than the full voltage or its coil will overheat quite easily.

    I'm thinking about Solid State Relays. They have a wide input voltage range, but I'm only talking about input voltage range because the Thread Starter has said nothing about whether he wants circuit 1 to come on when circuit 2 is barely starting or almost completely on. Next problem: A SSR can be told at what level to come on, but that involves resistors and fingers in the power line circuit. I'm afraid this website forbids that conversation. I will notify a Moderator.

    @Ishan Perusinghe
    If you're any kind of blue collar circuit board maker, speak up before the Mods lock this thread for being too dangerous.

    http://www.mouser.com/Electromechan...Z1z0x37vZ1z0x156Z1yzutolZ1z0x121&Ns=Pricing|0
     
  11. dl324

    Distinguished Member

    Mar 30, 2015
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    Google solid state relay opto and you'll find solid state relays with integral optoisolators/optocoupler. This is the first page I looked at using the above search: http://www.vishay.com/docs/83858/appnote56.pdf
     
  12. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    Yeah I'm not looking for anything dangerous . I'm just looking for a simple switch to turn on circuit one when circuit 2 has been turned on . The only difficulty I'm having is circuit 2 has dimmer . Which is making the switching difficult . I don't think anyone has suggested anything dangerous . At what voltage circuit comes on doesn't matter at this point . As long it's above 12 v
     
  13. #12

    Expert

    Nov 30, 2010
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    You mean as long as it's high enough to provide for a 60 watt LED driver?
    What does the label on the 60 watt LED driver say it wants for an input voltage?
     
  14. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    The led driver in circuit 1 has it own 240v input power as it's wired in Parrell . What Iam looking for is a mechanism to turn this circuit on / off when circuit 2 is on and off .
     
  15. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    The mechanism to switch on circuit 1 needs a trigger voltage from circuit 2 as long as the trigger voltage is say above 12 v then circuit 1 will come on . If trigger voltages drops below 12 v . Circuit 1 will shut off .
     
  16. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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  17. MaxHeadRoom

    Expert

    Jul 18, 2013
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    As per your post in another site, you have not disclosed all the information necessary to give an accurate opinion, no one is a mind reader here!!.
    Max.
     
    #12 likes this.
  18. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    I don't understand what I am missing ?
     
  19. Ishan Perusinghe

    Thread Starter New Member

    Jun 24, 2015
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    I have described everything I can . If you have a specific question I will try and give u the Info . But I summary I'm hoping the Ssr will turn on circuit 1 when circuit 2 is turned . Both circuits are in Parrell and have 240 v supply . The only difference is that the circuit 2 has variable pot / switch . That's what I need the keep the circuits separate as u don't want the pot to affect the voltage to the led driver in circuit 1 .
     
  20. dl324

    Distinguished Member

    Mar 30, 2015
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    That relay requires 90-250VAC to turn on.

    You should look for an opto SSR that can handle the load for your LED strip (you haven't mentioned load current). You also need to state whether you want to switch both neutral and hot wires or if you only need to switch hot. That will determine if you need DPST or SPST contacts.

    Here is an SPST example: http://www.vishay.com/docs/83816/lh1518aa.pdf. It will switch a 240VAC load at 300mA.

    With an opto relay, you can put the LED with appropriate current limiting and reverse bias protection in series with your 600W bulb load on circuit 2. When current flows in that circuit, it will trigger the relay and power the circuit 1 load.
     
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