Arduino 4 Channel Relay Module : Description of Connections

This guide is not intended for the children as it involves household supply electricity. Household supply AC is overpowered enough to kill a human. We believe that controlling AC powered things like a bulb with Arduino often scary to many of the sane, careful hobbyists. However, with proper precautions they can keep you safe. Here is Description of Connections of Arduino 4 Channel Relay Module. These Relays Create Clicking Sound While Operation and Not Suitable For All Works. For proper safety, please connect the AC supply routing through proper mini circuit breaker so that upon evocation of electric shock, the whole circuit gets disconnected from AC mains supply. Relay is a device to keep two circuits separate. We can blink one AC bulb with one relay module. We discussed about using 74HC595 Shift Register and how to connect 74HC595 Shift Register with relay module.

Question can be, why buy 4 channel relay module when 8 channel relay module is suitable with 74HC595 Shift Register? 4 channel relay module is for ordinary usage, like including inside an electrical connection box to control connection to the appliances. It’s size is quite small, cost is lower.

These relay modules will create mechanical clicking sound like switch – they are like mechanical switch. These are unsuitable for smooth blinking. Solid State Relay is a different type of relay, which is practical to use after getting used with hands on with these conventional relay to learn the basics. The optocoupler (817C Optocoupler) is a key component in these circuits.

Arduino 4 Channel Relay Module : Description of Connections

Connecting 4 channel relay module often confuses a new user. There are four separate circuits on one board. The AC connection part (which is screw terminal) provides a common (COM), normally open (NO) and a normally closed (NC) terminal. The common (COM) terminal will connect to live household electric connection. Other end of the appliance connected either such as normally open (NO) or normally closed (NC) terminal. Normally open (NO) and a normally closed (NC) terminal does opposite job. Doing a test with blink sketch will give the idea of the thing.

Other part is four ports to connecting to Arduino’s digital pins and with 5V DC from Arduino board. That is the easy and sufficient connection setup for controlling an ordinary AC appliance, such as an incandescent bulb.

The relay module has a separate 5 DC supply connection port with a jumper. That is for for isolation – 5V supply will be from separate source other than Arduino. That is slightly advanced and will need manipulation of the jumper.