4 Channel Arduino Relay Module

Hello again! I am heading to electronics store today to buy some new stuff for my project. The question is, if i buy a 4 channel DC 5V Arduino relay, can i use one channel for activating a 12V DC Fan? Or only actuators i can use are 5V, like 5V fan? Also, with the relay, will i be able to condition my actuators, like my fan will start working when the temperature is higher than 35 degrees? Or the relays can only turn on/off? Can relays work with sensor values, by the way of course i will use Arduino Mega 2560 and Arduino Ide code. Thanks in advance!!

Mega 2560 is phenomenal overkill. A Nano would be more useful for such a project. :grinning:

But i already bought Mega 2560 and i don't have so much money left for me to waste. Are you thinking i will burn my Arduino if i use 2560? Isn't there a way for me to use 2560 and 4 channel relay module?

Also, i want to add one more question to my questions in my first entry. Should i buy 5v battery adapter for each of the relay channels? I mean, i think i will need to connect relay module's vcc to my 2560, but what about 4 relay channels? Should i connect them to an external 5V battery?

Here is a perfectly functional 4 channels relay board that may the type of thing you are talking about.

SainSmart-4-Channel

That one is for AC loads and will not work for a 12v DC fan- but the principles are the same.

5v power into Vcc and Gnd, Arduino signal into the low voltage side (IN1, IN2, IN3, IN4). The output channels are essentially switches on the output circuit (eg, AC power to relay, relay to lamp, lamp back to power).

Relays only turn on and off. If you want to control a 12v DC fan, be sure to get a relay for a DC load. If you want to control the speed of the fan, you may wish to use a transistor circuit and not a relay circuit.

Thanks for the reply but unfortunately, all my loads are DC. If you can answer this question i will be really happy:

Should i buy 5v battery adapter for each of the relay channels? I mean, i think i will need to connect relay module's Vcc to my 2560, but what about 4 relay channels? Should i connect each of them separately to an external 5V battery, so it means 4x5 Volt batteries? Or do i need "ONE" external 5V battery for "all relays"?

SunStorm:
Hello again! I am heading to electronics store today to buy some new stuff for my project. The question is, if i buy a 4 channel DC 5V Arduino relay, can i use one channel for activating a 12V DC Fan? Or only actuators i can use are 5V, like 5V fan? Also, with the relay, will i be able to condition my actuators, like my fan will start working when the temperature is higher than 35 degrees? Or the relays can only turn on/off? Can relays work with sensor values, by the way of course i will use Arduino Mega 2560 and Arduino Ide code. Thanks in advance!!

The fact that they are 5V relays, refers to the COIL operating voltage, which in your case with Mega will be 5V.
The voltage/current you control with the relay contacts can be more than 5V, it depends on the limits set by the relays CONTACT ratings.
So your four relay unit can control a variety of devices, as long as they do not exceed the CONTACT rating.
If you want the relay to operate at a particular temperature, then you will need to program your Mega to read the temperature sensor and when conditions are met, switch the relay ON or OFF.

Can you tell us your electronics, programming, arduino, hardware experience?

Tom.... :slight_smile:

SunStorm:
Or do i need "ONE" external 5V battery for "all relays"?

We need more information, but yes, theoretically you could use one 5v source to power both your Arduino and your relay board.

In practical terms, it depends on the expected current draw, the milliamp hours of the battery, the frequency of the relay switching, etc.