Why is the simple relay circuit only half working

relaytroubleshooting

I am new to electronics and I am following the book "Make: Electronics" by Charles Platt.

I have built a circuit with a 12V DC power supply, a 1K resistor, a relay, two LEDs, and a momentary-on switch.

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When I turn on the power supply, one of the LEDs lights up. However, when I press the switch down (and hold it down) that LED goes out but the other one does not light up at all.

I have made sure all connections are good, and I have replaced every single component in the circuit, but it just doesn't seem to be working.

The only thing I can think of is that I was mis-sold a relay by Maplin. I asked for a "DPDT non-latching 12V DC relay" as it says in the book. The one I have has "1A 125V AC" and "2A 24V DC" written on it.

Any suggestions? Cheers.

Best Answer

You've wired it up incorrectly. See this : -

enter image description here

Try swapping the wires to the two most central pins. I got this PCB detail from here and although it is not the same part it is classified as a BT type 47. The Maplin link doesn't show the wiring so hopefully this one will be compatible.

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