Can I use this relay to turn on or off 12V DC electronic equipment?
creativen:
Can I use this relay to turn on or off 12V DC electronic equipment?
Relay_Module__Arduino_Compatible___SKU__DFR0017_-DFRobot
Yes, as long as the amount of 12V current you are switching on and off don't exceed the maximum current rating of the contacts on the relay.
Lefty
The dfrobot page has a link to the data sheet for the relay which states that it is rated up to 5A at 24V DC.
EDIT: whoops, it links to the wrong datasheet :P. Here's the correct datasheet.
Do you know what is the maximum current rating of the relay for 12V DC? I am not sure reading the datasheet.
I am trying to turn lock and unlocked this solenoid door:
@lefty..... what might it be about that relay that would cause it to have different current ratings on the NO vs NC connections?
And is that a common thing in relays in general?
JimboZA:
@lefty..... what might it be about that relay that would cause it to have different current ratings on the NO vs NC connections?And is that a common thing in relays in general?
You know I saw that rating and was somewhat surprised as I've never seen that kind of rating ever before. I have seen a given relay have lower current rating for switching DC then AC on the same physical relay as breaking AC current gets the benefits of the AC voltage doing zero crossings, where as DC always creates higher arcing on the contacts for the same current value. So maybe a datasheet error really meaning 10 amps max if AC or 5 amps if DC? Either way one should most likely limit DC current switching to 5 amps max for that relay unless better information is forthcoming from the manufacture.
Lefty
But when I connect to that solenoid lock door, and following the code
//Arduino Sample Code
//www.DFRobot.com
//Last modified on 14th March 2012 by HJS
//This code has been updated to work with the sample code provided in the Wiki
int Relay = 3;
void setup()
{
pinMode(13, OUTPUT); //Set Pin13 as output
digitalWrite(13, HIGH); //Set Pin13 High
pinMode(Relay, OUTPUT); //Set Pin3 as output
}
void loop()
{
digitalWrite(Relay, HIGH); //Turn off relay
delay(2000);
digitalWrite(Relay, LOW); //Turn on relay
delay(2000);
}
from Relay_Module__Arduino_Compatible___SKU__DFR0017_-DFRobot <-- here using led
but the solenoid doesn't show any changes. Is it possibly means that the solenoid door lock require more than 5 A?
but the solenoid doesn't show any changes.
Do you here the relay click?
Is it possibly means that the solenoid door lock require more than 5 A?
If you put more current through a relay than its ratings, first the life is shortened, and then the contacts weld together. So in either event your solenoid should move.
but the solenoid doesn't show any changes. Is it possibly means that the solenoid door lock require more than 5 A?
That sounds to me like a wiring problem on the output contacts side of your relay/solenoid/power source setup. Or maybe whatever door solenoid voltage source you are using is not up to the task? Can you post a drawing of your output wiring?
Lefty
Yes I do hear a click!
what does it mean? my english is not really good.
If you put more current through a relay than its ratings, first the life is shortened, and then the contacts weld together. So in either event your solenoid should move.
Yes I do hear a click!
what does it mean?
It means the relay is working and the fact that you solenoid does not move is down to the fact that either you have not wired it up correctly or your power supply cannot supply enough current.
Measure the voltage on your power supply and see if it dips when the relay kicks in.
JimboZA:
@lefty..... what might it be about that relay that would cause it to have different current ratings on the NO vs NC connections?And is that a common thing in relays in general?
It's not uncommon, especially in the world of automotive relays. The standard Bosch/Tyco relay can carry 40A on the NO and 30A on the NC. In general the idea is that the NO item is the high power contact you want to switch on and off. So in general if there is a rating difference the NO is usually the higher of the two.
additional, the powerjack could supply till 2A
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.
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.)
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.
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).
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
