Pages: 1 [2]   Go Down
Author Topic: Can I use this relay to control 12 V DC?  (Read 992 times)
0 Members and 1 Guest are viewing this topic.
Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 631
Posts: 34506
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

That wiring is wrong.

You need to connect the solenoid directly to the 12V line not back to the arduino pin 13. You are connecting the arduino output into a very low resistance and overloading the pin possible damaging it.
Logged

Johannesburg. UTC+2
Offline Offline
Faraday Member
**
Karma: 105
Posts: 4653
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

The way I read that diagram, the relay is switching a 5v 40ma max supply from pin 13 which is supposed to trip that solenoid?

But I thought from earlier posts the solenoid is 12v? Surely you should be putting 12v into the common on the outpit side of the relay and switching that? I think the  DFRobot tutorial puts 5v in there just as an example, since that's all you need to drive the LED. (I'm curious why they didn't source that from the 5v power pin though, rather than an i/o pin which they switch on and leave on.)
Logged

The Elders of the Internet know who I am
I'm on LinkedIn: http://www.linkedin.com/in/jimbrownza

Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 631
Posts: 34506
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
I'm curious why they didn't source that from the 5v power pin though, rather than an i/o pin which they switch on and leave on.)
Simple - they are idiots.
Logged

San Diego, CA
Offline Offline
Jr. Member
**
Karma: 1
Posts: 66
A sociable geek chemist
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

It sounds like a power supply problem. The relay isn't the fault here. If it is switching (and works for the LED) then you are fine. The Amperage of your power supply is much lower than the rated valuse for the relay (once again the relay is fine). Therefore I would look at the power supply.

Edit just read the above:

Yes, your 12V power supply should come in to the Common pin on the relay. You should NEVER be sourcing the power form the arduino, that defeats the point of the relay.

Also I don't see if the relay has a reverse diode to take care of back EMF when the relay disengages. If it doesn't I would wire one in (I have a feeling arduino's don't like 300V pulses too much).
« Last Edit: January 18, 2013, 03:54:39 pm by PedroDaGr8 » Logged

Johannesburg. UTC+2
Offline Offline
Faraday Member
**
Karma: 105
Posts: 4653
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
I don't see if the relay has a reverse diode

Well the pic of the module certainly shows there are diodes, but the narrative in silent on the matter and it would be a guess that they are fly-backs


* Relay_Module_DFR0017.jpg (23.06 KB, 267x256 - viewed 23 times.)
Logged

The Elders of the Internet know who I am
I'm on LinkedIn: http://www.linkedin.com/in/jimbrownza

Pages: 1 [2]   Go Up
Jump to: