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I've got this single-channel relay for my Raspberry Pi. The relay has 6 pins instead of the usual 3, more over out of the box there was a jumper connecting 2nd and 3rd pin (I'm counting pins from top to bottom starting with 1). This is my first ever interaction with both relay and a Raspberry Pi. Why is there a jumper on the relay? And how to use it?

I've hooked up 1st pin to 5V PWR GPIO on Raspberry Pi, 4th pin to GPIO4 and 6th pin to GND. In given configuration LED on relay board lights up whenever I send GPIO.LOW output on GPIO4 but relay isn't clicking.

Relay board

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  • \$\begingroup\$ Please provide a link to the manufacturer's datasheet for the relay. Also, please provide a schematic of how everything is connected...talking about "first pin" and "fourth pin" can be ambiguous. \$\endgroup\$ Mar 23, 2021 at 21:21
  • \$\begingroup\$ There are a few variations of these boards - they all look much the same. Of course, you need the ‘right one’ for it to work. I’ve sketched out the circuit on previous occasions to determine if it is the right one or not. Its all very confusing!! \$\endgroup\$
    – Kartman
    Mar 23, 2021 at 23:29
  • \$\begingroup\$ @ElliotAlderson, I wish I could. There's absolutely zero identifiers on the board (apart from those on the actual relay itself). So I don't have any documentation whatsoever. \$\endgroup\$ Mar 25, 2021 at 14:43

2 Answers 2

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This is a 12V relay, so you need a 12V power source to operate it. I'm not sure if your raspberry pi GPIO will be able to operate it even if you provide 12V to VCC. You may want to get 5V relays like this that are designed for the raspberry pi.

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  • \$\begingroup\$ Thanks a lot! That's what I've ended up doing (got Waveshare RPi Relay Board). Works like a charm. \$\endgroup\$ Mar 25, 2021 at 14:37
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You have a relay module similar to if not exactly like this

enter image description here

The basic components are an optocoupler a For input, a transistor for driving the relay, and a status led, flyback diode and passive parts like resistors.

Of you measure the two pins marked vcc they are the same connection and so is both ground pins.

IN + is the high side of the opto and IN - is the low side. The jumper is used when you want to drive the opto and relay from the same voltage. In your case you probably don't.

Easiest is to disconnect the jumper and use a 12V supply for the relay and 3.3V for the IN+. RPi have 3.3V logic not 5V.

You probably want to use a multimeter with a continuity mode and trace out all the connections to make sure. No guarantees im right and you can be risking your RPi or worse.

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