Relay,what pins are what. - Page 1
Forum section: electronics / beginners

author: RobH
author_rank: Regular Contributor
timestamp: October 30, 2022, 08:35:21 pm
content: Before I cam e here, I have googled this question extensivly, and I can't find a definitive ansewer.Anyway, I have a 5 pin 5v DC relay, which has 3 pins on one side, and 2 on the other.Using a DMM I have a connection between 2 end pins, and no connection between the other 2 end pins. I have established that the middle pin on one side is the common pin.My questions are: which pins do I connect +Vcc and -Ve, is it the ones with no connection, as when I do that and apply 5v , the relay clicks. Also when something is connected to it, like a pump etc, , I assume one side goes to the common pin and the other side goes to the 2 pins which are connected.I've probably assumed incorrectly, but I would like to know how to connect them up, as I have never used one before.From the picture the 2 pins on the right have no connection between them.Thanks

author: ataradov
author_rank: Super Contributor
timestamp: October 30, 2022, 08:56:08 pm
content: Measure the actual resistance between the pin. It is highly likely that round pins are the coil, center pin is common and other flat pins are NO and NC.

author: jpanhalt
author_rank: Super Contributor
timestamp: October 30, 2022, 09:02:13 pm
content: Not all 5-pin relays are the same, but the attached is a common configuration. Check for coil resistance as suggested. You can also identify positively the NO contact.

author: Ian.M
author_rank: Super Contributor
timestamp: October 30, 2022, 09:22:25 pm
content: Its also common for small PCB mount relays to have markings indicating the pinout, maybe even a contact diagram on the top. At the very least it should have a part number, which will probably let us find you a datasheet for it.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: October 30, 2022, 09:41:22 pm
content: Looks like an NEC signal relay.You will find two of the end pins are the coil. That will measure around 150-300 ohms depending on the coil voltage.The other three pins are the contact pins. It looks like a 1formC configuration so one pin will be the armature and the other two will be the NO and NC pins. You would need to measure which is which once you have the coil operational.

author: wraper
author_rank: Unknown
timestamp: October 30, 2022, 09:59:41 pm
content: Why not provide a photo of the marking or just write its model so there are no second guesses?

author: RobH
author_rank: Regular Contributor
timestamp: October 30, 2022, 11:08:55 pm
content: Quote from: wraper on October 30, 2022, 09:59:41 pmOk, yes I should have done that , doh!Anyway , it is a SHRACK PE514005. the model number is not easy to read but I thin k it is right

author: ataradov
author_rank: Super Contributor
timestamp: October 30, 2022, 11:12:08 pm
content: Ok, but this is trivially googled. What is the problem here?https://www.newark.com/schrack-te-connectivity/pe514005/pe514005/dp/08H3002It looks like I was correct in my guess.

author: wraper
author_rank: Unknown
timestamp: October 31, 2022, 10:00:07 am
content: Yeah, pinout on a second page of the datasheet.

author: RobH
author_rank: Regular Contributor
timestamp: October 31, 2022, 10:07:13 am
content: From the datasheet, which I couldn't find before,the 2 round pins marked A1 and A2 are the coil,. The middle pin marked 11 is the Common and the other 2 flat pins marked 14 is NC and 12 is NO .I get a resistance reading of 125 ohms across pins A7 and A2, being the coil, and a reading of 0.6 ohms between pins 11 and 12.As I don't know, do I connect things like lights and leds etc to the NC and the NO pins, and also do I connect the coil to +Ve and -Ve.I just want to be sure I am doing it correctly.Update:I found from other sources how to connect what to which pins nowThanks

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 03, 2022, 01:17:19 pm
content: Engage brain before applying voltages.The relay coil has some resistance, and you can measure this with an ohm meter. When you apply enough voltage to the coil, it clicks and the contacts are switched. And you can measure those contacts switching.There are some weird relays though.One of the weird things is a built-in diode over the coil, and then the polarity of the applied voltage is important.There are also bi-stable relais, that witch with two different coils, or by reversing the voltage over the single coil.

author: RobH
author_rank: Regular Contributor
timestamp: November 03, 2022, 05:41:19 pm
content: Yes I worked that out and I put a diode over the coil / pins , and like I said , I have connected up the relay correctly as it works as it should.I also am aware that all relays are not the same, and so may be connected differently, but I'll cross that bridge when I need to.Thanks