Relay module has no output power??

Other Hardware General Electronics
1

Hi guys, I read a few recent similar posts but not quite the same problem. I have set out for a device to power another device on and off to make life easier for myself.

I came across some relays which I have no clue about but thought if I put a relay inline of device one's power supply then used signal from device two to trigger then jobs a golden. Or not as no experience things obviously aren't that simple.

So I purchased two relay switch modules shown in attachments. And I wired them both inline with my phone charger (one at a time of course) and they both light up then when I connect the channel (switch) to the positive on the input another light shows on the both and one makes a clicking sound but I never get and power from the output??

The power supply is 5v like the relays and is 2.5a which the solid state relay is 5v 2a.

I have checked with voltmeter on the two output pins and other wiring circuit possibilities like with + on output pin and - on the negative input pin but nothing at all.

If anyone with experience or even a brain could shine some light I would be overly fearfu...

Thanks for your time.. c

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2

A relay is basically just a remote controlled switch. The clicking you heard on the first module is that switch closing. The second relay is a bit more complicated because it uses a triac (probably) and can really only be used to control AC.

In either case, you won't get power out of them unless you put power in.

3

Opensourcerer:
Hi guys, I read a few recent similar posts but not quite the same problem. I have set out for a device to power another device on and off to make life easier for myself.

I came across some relays which I have no clue about but thought if I put a relay inline of device one's power supply then used signal from device two to trigger then jobs a golden. Or not as no experience things obviously aren't that simple.

So I purchased two relay switch modules shown in attachments. And I wired them both inline with my phone charger (one at a time of course) and they both light up then when I connect the channel (switch) to the positive on the input another light shows on the both and one makes a clicking sound but I never get and power from the output??

The power supply is 5v like the relays and is 2.5a which the solid state relay is 5v 2a.

I have checked with voltmeter on the two output pins and other wiring circuit possibilities like with + on output pin and - on the negative input pin but nothing at all.

The fact that the mechanical relay clicks when you power it means it's working.

But, what a relay does is act like a switch.

Picture this: A light bulb in your home.

WARNING - THE FOLLOWING IS JUST AN EXAMPLE. DO NOT ACTUALLY CUT WIRES IN YOUR HOME!

The light, without a switch, would stay on all the time. Now, cut one of the wires. The light goes out. Now, touch the two cut leads back together. The light goes back on.

NOW, take the two cut leads and instead connect them to the relay. Now, when you power the relay, it will click, the circuit will "close" (that is, touch together) and the light will glow. Turn the relay off and the relay opens (that is, no longer touched together) and the light goes out.

The whole point of using a relay like this is that it ISOLATES the controlling side from the mains-voltage light side. It, for example, would allow an Arduino board to safely turn the light on and off under software control.

No power "comes out of" the relay. It's merely a low-voltage-dc-controlled switch.

Make sense?

4

Thanks for the reply guys.. so I understand a relay is basically a switch as I said my aim is not to get power from it but release the power put in to it when triggered..

Now I'll explain my wiring as I may have worked out the problem..

I have a old phone and a 5V 2A phone charger.. i cut the phone charger wire in half then wire it from plug socket to module DC in + and - then I on the other side of the relay I connected the other half of the charger cable and plug into phone. Then putting a wire from the ch input (next to DC in + & -) and using DC in + to trigger it but getting no power on the phone side.

Now when I'm wiring the ch to the DC in+ am I creating a short circuit?? So instead need a external source to trigger the relay (switch)

Or

Am I supposed to wire it in a different sequence?

Thanks again.

5

A diagram of your circuit would make things easier or us to follow; just draw it on paper and photo / upload it

6

ricky101:
A diagram of your circuit would make things easier or us to follow; just draw it on paper and photo / upload it

So I will post a link to my drop box that has four pictures in it... two of each module but one of each complete circuit then one of a close up of the relay module it's self.

Hope this helps as my drawings would confuse anyone!!

https://www.dropbox.com/sh/deihpqojwwpos1w/AABPU_kaGvuyyW3Tu7fMTNrRa?dl=0

7

You can not use a solid state relay to switch low voltage DC. You need to switch the mains input.

You can switch this with a mechanical relay. When it clicks you should see continuity between the common and the NO connectors. So that is where you wire up the break in ONE of the wires of your charger output. You seem to have broken both wires.

8

Grumpy_Mike:
You can not use a solid state relay to switch low voltage DC. You need to switch the mains input.

You can switch this with a mechanical relay. When it clicks you should see continuity between the common and the NO connectors. So that is where you wire up the break in ONE of the wires of your charger output. You seem to have broken both wires.

OK great so i am glad you confirmed i am on the right path.

i did try put + & - from the mains 250v 5A into the solid state relay with nothing else connected to it and it just went pop!!

with the mechanical relay when i connect it as i showed in pictures with the IN and DC+ connected the light comes on and the relay clicks but if i put a voltmeter to the COMMON and NO i get no reading.
should it still put out power with the DC+ and IN connected or is that just for testing the switch??

PS, both broken wires was disconnected i just pulled it back out of packaging to take pictures..

thanks for your help.

9

i did try put + & - from the mains 250v 5A into the solid state relay with nothing else connected to it and it just went pop!!

Yes it would. You seem to not get the fact that you only have to cut one of the wires and wire up the relay to either side of this single cut wire not both.

but if i put a voltmeter to the COMMON and NO i get no reading.

You will get no reading with a voltmeter. If you put a digital voltmeter into the resistance mode it will show when the relay clicks there is no / very low resistance between the Com and NO contacts.

You don't seem to get the idea, a relay is a switch, there is no power out of a mechanical relay, you need to put the switch in one of the leads, not both.

10

Ok so i think i really do understand what you mean by its a switch.. for example a normal circuit would go positive switch device negative and a switch will just break and re connect the circuit.

But with any of the two relays (switches) im trying to use i just cant get my head around how to wire it so that it would charge my phone when i send a signal to it.

If i cut just one wire then it would go (+ to DC+) then (NO to device+) then (device- to -)

if this is still wrong then you could explain how you would wire it so the phone would charge when the relay is triggered??

sorry if i am stressing you over something that is probably so simple i depreciate it massively!!

11

My suggestion is to AVOID ANY MAINS POWER until you have a concept on how things work.

You have cut the plug off a charger, connected the supply lines to the relay coil , then simply put the plug on the switched side contacts. There is NO WAY that will work. The switched side is isolated from the coil side. Power will NEVER jump across. You need a second supply, but it doesn't seem to make sense that you are going to plug in a 5v wallwort to turn on a relay that turns on a 5v wallwort.

12

I quite agree with that. It is ONLY the mechanical relay that will work, chuck the other.

This is what you need to wire up.

Relay circuit.jpg
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What you are going to do for the relay power supply and relay control I don't know.

13

You could wire things up like this if you want.

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14

OK I think that explains a lot... so the connectors nc no and common are just putting a switch in a circuit.. then the DC+ DC- and in are used to power the switch and activate trigger it??

If that's the case then I can see how everything everyone has said makes sense..

15

Good.

Did you know that NO stands for normally open and NC for normally closed, with normal meaning the relay not energised.

16

Yes, I new all the abbreviations just clearly had no idea how a relay module works...

Sorry for being so blind

17

Ok, im still waiting on my new relay modules to arrive but i think its best i should try learn a bit more about them to help with other projects...

I bought a 5V 2A module as i though that's what i would be putting through it.. but it turns out nothing actually goes through it.
Q: is the ratings of the relay just what its going to take to power and operate the switch?

18

No.
There are two ratings, what the switch contacts will take and what it takes to drive the coil.
So 5V 2A makes no sense for either of those. 5V is way too low for a switch maximum voltage and 2A is way way too high for driving the coil.
So presumably who ever you bought this off doesn't know what the hell they are talking about.

19

Grumpy_Mike:
You could wire things up like this if you want.

Relay Charger.jpg
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So my switch arrived today and this circuit worked perfectly.. I just didn't have the arduino connected to it. But just triggered it with the DC+

For the trigger can I take the 5v from anywhere as long as the source has its own ground??

PS, the relay module wasn't recommend to me I just browsed google and thought I could use it for my project.

Thanks Carl

20

For the trigger can I take the 5v from anywhere as long as the source has its own ground??

Yes.
In fact you might not need a 5V at all. A lot of these relay modules work with negative logic. That means if you connect the relay control line to ground it will switch on, Otherwise you can connect the relay control to the 5V relay power line.