Using a transformer in a project, need advice

Mr. SharpeMr. Sharpe Posts: 1,113
edited February 24 in Electronics
So I’m using a 120v to 12v transformer and i need advice. I have it actuating a relay and I just hooked it up and turned it all on and it’s getting hot enough to stink and melt plastic. The issue is is that the transformer has 117v input written on it and it’s getting 121v I think, output is rated at 12v and I’m reading 14v.
I don’t mind purchasing another one, the only thing this transformer is doing is actuating the relay which is rated for .5a input and so is the output of the transformer.

I think all that’s happening is that it’s getting too much going into it. The switch does have a small led on it also, didn’t know if that would make a difference.

A weird thing to note is that the transformer has 3 output legs, two are 6v and one is 0v. Hot and neutral of course
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Comments

  • FestYboyFestYboy Posts: 2,657
    You're overloading the output stage with too big a load electrically. Please explain what all the components are and the end goal, I can draw you a schematic.
  • Mr. SharpeMr. Sharpe Posts: 1,113
    Will pics work?
    mlgq1qvcdaey.jpg

    5aq5uyxqao79.jpg

    The info on the relay says input voltage is 10ma which is .01amp. And the output of the transformer is 1amp. Your help is appreciated. I thought I had this mess figured out when I bought it

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  • Mr. SharpeMr. Sharpe Posts: 1,113
    The goal is for the transformer to actuate the relay.
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  • FestYboyFestYboy Posts: 2,657
    You're feeding the DC relay with AC voltage. That's the biggest issue. You need to rectify the output side of the transformer before it gets sent to the relay.

    What you should be using is a wall wart with a 12vdc output at .25-.4A put, then fuse it with a .5A fuse slow blow.
  • Mr. SharpeMr. Sharpe Posts: 1,113
    ds9zhw3w9a16.jpg

    I know you said .25-.4amp, would this work also?
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  • FestYboyFestYboy Posts: 2,657
    Depends on the sensitivity of the relay, and should work fine for testing, but I'd invest in a larger for long term use.
  • Mr. SharpeMr. Sharpe Posts: 1,113
    Ok yes it’ll be used long term, could you recommend me some please or at least show me some values I need to look for?

    Hard to say about sensitivity on the relay because it’s reading 119 without it switched on... shouldn’t the hot line in be connected to the no. “1” on the high side of the relay? Now I feel like it may be defective
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  • FestYboyFestYboy Posts: 2,657
    The range listed earlier will do the trick. The relay should only control one leg of the circuit, so either the hot or the ground (ideally always the ground as there is no voltage after the load). If you are controlling the hot side, leg 1 will always read input voltage no matter what. The wall wart will go to legs 3 and 4 only.
  • delkaldelkal Posts: 284
    edited February 25
    Mr. Sharpe wrote: »
    Hard to say about sensitivity on the relay because it’s reading 119 without it switched on... shouldn’t the hot line in be connected to the no. “1” on the high side of the relay? Now I feel like it may be defective

    You might have fried the relay connecting it to AC. It should not matter if the hot ac current is plugged into 1 or 2. No AC CURRENT should flow between 1 and 2 with no input to the relay (3 and 4 unplugged). You can't tell that with an voltage meter.

    You are experimenting with some high voltages and you don't want to be poking around the high side with a multimeter unless you really know what you are doing. I would rig up a simple circuit with a LOW WATTAGE light bulb, proper base, and all of the wires wingnutted like they were being installed. The only part of the AC side you should touch should be the power cord you are plugging in.

    Wire a lightbulb and plug it in.
    It should light.

    Then unplug everything and put the relay in the circuit. Cut a wire (preferably before the lightbulb) and connect one side to load 1 and one side to load 2.

    Plug it in.
    The lightbulb should NOT light.

    Put your 12 volt current on 3,4.
    The lighbulb should light



  • FestYboyFestYboy Posts: 2,657
    6i4fnmjs0zdb.jpg
  • Mr. SharpeMr. Sharpe Posts: 1,113
    I’m fine with working 120... it’s the amps I have a problem with ;)

    But in al seriousness using the relay and etc. seems more of an issue than good thing so I may not use them at all. In my project I don’t have to use them I just wanted a way to not have the led in the power switch interfereing with the line voltage.
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  • Mr. SharpeMr. Sharpe Posts: 1,113
    So if I do decide to just use the switch without all the relay and transformer etc. and I use it to close the neutral side of the line do I have to use anything besides just wiring it up? The switch is already rated for 10a at 120v.
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  • mhardy6647mhardy6647 Posts: 18,753
    edited February 27
    Isn't a single-pole switch usually installed in the hot line not neutral?
    (or, I suppose, both legs can be switched with a double-pole switch)

    but, when all is said and done:
    You must remember this
    a switch is still a switch...
    1bxzq0pl23qt.png

    :|

    "It's like watching a roomful of people who couldn't get through college algebra discussing the flaws of quantum physics theory. I guess it could be fun, but it's ultimately a waste of time." -- seen on audiokarma

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  • FestYboyFestYboy Posts: 2,657
    Correct, by code it's the hot line that needs switched.
  • Mr. SharpeMr. Sharpe Posts: 1,113
    FestYboy wrote: »
    The relay should only control one leg of the circuit, so either the hot or the ground (ideally always the ground as there is no voltage after the load). .

    So by code I can’t switch the neutral leg?

    Here is the switch legs
    r845815ys3s6.jpg

    In this I have the hot line switched to send voltage to the transformer. I do t guess it’ll matter much.

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  • Mr. SharpeMr. Sharpe Posts: 1,113
    *wont matter much
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  • FestYboyFestYboy Posts: 2,657
    Which color is which? If that's AC, red should be white. If it's DC, then the ground is switched.

    I think the biggest problem is none of us know what all of this is, there's no clear understanding of what the circuit is supposed to be.
  • delkaldelkal Posts: 284
    edited February 28
    With all AC you always want to switch the hot (black) side before it goes to a device. So after the switch is off there is no voltage going to the device. If you put a switch on the neutral side (white) the AC voltage energies the device (but it won't work because the circuit is not complete).

    Stand in a puddle of water and touch the device and you will know the difference.
  • Mr. SharpeMr. Sharpe Posts: 1,113
    FestYboy wrote: »
    Which color is which? If that's AC, red should be white. If it's DC, then the ground is switched.

    I think the biggest problem is none of us know what all of this is, there's no clear understanding of what the circuit is supposed to be.

    Red is neutral and the bottom two are hot. sorry for the vagueness of the thread.

    Okay I’ll switch the hot side with no problems:)


    delkal wrote: »
    With all AC you always want to switch the hot (black) side before it goes to a device. So after the switch is off there is no voltage going to the device. If you put a switch on the neutral side (white) the AC voltage energies the device (but it won't work because the circuit is not complete).

    Stand in a puddle of water and touch the device and you will know the difference.

    Favorite past time ;-) like sooo funnn
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