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Topic: Relay with DC load (Read 395 times) previous topic - next topic

dualcei

Hello,

I bought a relay module to use with my home automation project, but on the relay cover are writen only AC voltages and currents, like "10A @ 250Vac ; 15A @ 125Vac". The control are 5Vdc, ok.

I want to control a DC load (1A @ 12Vdc) with this relay module controlled by an Arduino pin (5Vdc).

Can I do this with this relay module? If connect this load (12V and 1A) at the load pins of relay it will be work normally?

Thanks a lot!

terryking228

Hi,

Please point to or photo the exact relay module you have...

And, importantly, what is the load device rated at 12V 1A ?? 
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

dualcei

#2
Jun 14, 2018, 12:49 am Last Edit: Jun 14, 2018, 01:05 am by dualcei
Hi terryking,

The picture below describes the relay module, the DC load and what I want to do.



The load device is a 12V solenoid valve.

Can I do this circuit?

Regards!

rw950431

Yes.  240V relays will happily switch 12V  but not the other way around...

terryking228

Hi,

You also need to consider the switching of a DC inductive load like that solenoid.  You need a diode (typical 1N4007 type) in reverse direction across the solenoid coil to absorb transient voltage.

See "AC vs DC: Why do I care?"  on THIS PAGE.
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

dualcei

Thank you rw950431 and terryking228 for the answers!


Terry,

Thanks for the link. If I understood this care is applied on loads with large current and with high inductance, like motors. My solenoid is a 1A only. But if I need to use a diode like this, can you post too a picture showing how I can put the diode on the load?

terryking228

Quote
showing how I can put the diode on the load?
The diagram you showed seems right.

The diode should be connected as close as possible to the solenoid terminals.

YES, you need a diode even on 'small' inductances like your solenoid.
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

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