wireless receiver and led light

Discussion in 'The Projects Forum' started by 2electrified, Aug 15, 2013.

  1. 2electrified

    Thread Starter Member

    Sep 5, 2011
    30
    0
    Hi,

    I have a wireless transmitter and receiver and I was wondering if its possible to add a led light to the receiver so when the relay clicks on, light goes on, then goes off. The reason for this the receivers are mounted in a weatherproof box and its hard to hear if the relay is clicking or not. The led would be mounted outside the box for visual. Is this possible? There are five wires in the receiver. Red and black - power needed for the receiver (12v), two white wires that are output to trigger what is going to turn on when the relay is enegerized, and blue wire which is the antenna wire. Thanks Lisa
     
    Last edited: Aug 15, 2013
  2. wayneh

    Expert

    Sep 9, 2010
    12,094
    3,033
    It's likely you could put an LED and a current limiting resistor in parallel to the relay poles, so that when the relay is energized, the LED will be lit.

    Does that sound right?
     
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  3. Shagas

    Active Member

    May 13, 2013
    802
    74
    Since no one has any input , i'll try to help with this.

    Hmm not sure what you are asking.You want to know how to connect an led so that when the relay switches on then the led goes on?
    I'm guessing you don't have any experience with electronics.


    If so then you need to first see where the relay is connected . Open up the reciever (disconnected from power first) and see if the relay switches the positive wire or the connection to ground . You will need to trace the wires to the relay and see , better if you open it up and take a picture maybe so we can see.
    Then once you find it you just connect the cathode other led to ground and the anode to the output of the relay through a 1-1,5k resistor ( depends on which side the relay switches) and thats it. You can solder the led to some wires and lead them out of the box if that's what you want
     
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  4. 2electrified

    Thread Starter Member

    Sep 5, 2011
    30
    0
    @Shagas - here a two pics of the receiver. And yes to the question you asked. I would like for the LED to turn "ON" when the relay is triggered. Now the LED that is on the board now is only used for syncing the transmitter/receiver. I already had the led and current limiting resistor set up, I just can't find the appropriate leads to connect to. First I connect to red and black leads, well that left the LED on all the time, then I connected, positive LED lead to red feeding in 12v, then moved along the relay to each white wire separately and nothing would light it up. I may be missing something.
     
  5. Shagas

    Active Member

    May 13, 2013
    802
    74
    Try connecting the led like this:

    ledtransmitter.jpg


    Your LED negative pole (shorter lead) goes to the black blob and the positive lead (longer lead) goes to the trace that I've marked with a red line.
    Have you tried it like that?

    Btw is it just me or are those some crusty solder joints?

    edit: nevermind the writing on the picture . The "cathode' should have been in black
     
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  6. wayneh

    Expert

    Sep 9, 2010
    12,094
    3,033
    Don't forget the resistor, 470Ω or more. I think you know that but it never hurts to remind folks.

    If you want the LED to later go off, even while the relay remains energized, you'll need a 555 timer IC to make a delay. Alternatively, you could make the LED pulse briefly when the relay is first energized. Basically you light the LED as you charge a "large" capacitor through the LED and a resistor. The LED goes off once the capacitor fills up. You have to also include a high-ohms resistor to drain the cap when the power is off.

    Personally, I think it's less ambiguous information for the operator to look at the LED and see the status of the relay. No guessing then.
     
    Last edited: Aug 15, 2013
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  7. 2electrified

    Thread Starter Member

    Sep 5, 2011
    30
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    @shagas - I tried it that way. I have the small led connected to ground (black wire) and the long led with resistor connected to the white wire - no light. I even moved the long led to the next white wire - still no light. Yeah those solder joints were ugly to being with. I like to keep my joints clean. When I get the right configuration, I will go back and clean up the entire board.
     
  8. 2electrified

    Thread Starter Member

    Sep 5, 2011
    30
    0
    I had a 22K resistor on the setup. Lemme try a higher resistor and see if that works.
     
  9. 2electrified

    Thread Starter Member

    Sep 5, 2011
    30
    0
    I tried a 330K resistor and it did not light the LED.
     
  10. wayneh

    Expert

    Sep 9, 2010
    12,094
    3,033
    With 12V, and a "normal" LED that you might light to 12mA, the proper resistor would be 1,000Ω. You can go as low as ~470Ω without immediately damaging the LED.

    A 22K or 330K resistor would not allow enough current to light an LED.
     
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  11. Shagas

    Active Member

    May 13, 2013
    802
    74
    As wayneh said , use a 1k resistor , also try a diffrent LED . Maybe you connected it wrong before and burned it accidentally or something
     
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  12. 2electrified

    Thread Starter Member

    Sep 5, 2011
    30
    0
    Yeah I tried a 1M ohm 1/4 watt resistor after I sent my last message. Not such luck. The LED is 5mm. All the resistors I tried in the past all worked when I connected the leads the receivers input power, but I am stumped why I can't get the LED to light up when the relay gets triggered.
     
  13. wayneh

    Expert

    Sep 9, 2010
    12,094
    3,033
    Every resistor you've mentioned is far too large an ohms value. Anything beyond 5K or so will be dim at best. Beyond 20K or so you won't get any light whatsoever.

    Try 1K
     
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  14. 2electrified

    Thread Starter Member

    Sep 5, 2011
    30
    0
    Yes I did notice the light was dimmer when I went with higher values. I will try 1k and see. I am hooking it up per shagas suggestion on his diagram that he posted from the pics I uploaded showing how to hook up the leads. If this doesn't work, I am throwing in the towel. I tried every possible connection on the relay.
     
  15. 2electrified

    Thread Starter Member

    Sep 5, 2011
    30
    0
    I would like to thank you guys for helping me out. Unfortunately I could not get it work. Without spending anymore time on it right now, I have decided to give up on this project. I know this will be bothering me in the back of my head, but when I have more time then I may come back to up, but for now I have to move on to other repairs and projects. Thanks again.
     
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