relay
I`m new to electronic stuff, I was reading an artice on how control AC light using arduino, In part of solution there is a relay module which has a VCC and GND and IN and COM and NO and NC, but I don`t have that module instead, I have a relay like this:
can you please help me to find VCC, GND and IN in my relay? Thanks
Typical relay module clone, they are all similar. Below schematic is per channel.
Keep in mind that RY-VCC (JD-VCC in the schematic) is for the Relay section, while VCC on the 4 pin connector is for the opto-isolated side.
https://arduinoinfo.mywikis.net/wiki/ArduinoPower for a full wiki on using these.
When we look at the internal circuit diagram of the relay it looks like the following:
I have also added one motor to show how the connections are to be made.
Vcc is the signal given by the microcontroller (one of the output pins from the Arduino). When this signal is given the SPDT switch changes state to NO. This completes the circuit and the motor will rotate.
Note Vcc is just a 5v signal if from the microcontroller (Assuming this is the rating of the relay). But Bat2 needs so supply the required voltage and current for the motor to run.
Now moving onto what you want to achieve in your project, the description is vague. You are running 2 pairs of motors with 4 Relays. I presume each pair is controlled by 2 switches. One for moving forward and one for moving backward. The same for the other pair.
The circuit diagram looks like the following:
Truth Table: U1 - M1 and M2 Forward
U2 - M1 and M2 Backward
U3 - M3 and M4 Forward
U4 - M3 and M4 Bakcward
U1 and U2 - Nothing
U3 and U4 - Nothing
All other combinations can be inferred as M3 and M4 are isolated from M1 and M2. You have to make sure your battery can handle running all 4 motors at once though.
Best Answer
Your relay has 5 pins, which are almost certainly the two connections to the coil, and the common (COM), normally-open (NO), and normally-closed (NC) connections of the switch.
To find out which is which, use a ohmmeter. There will be some finite resistance between the two coil leads, probably a few 10s of Ohms, maybe up to 100 or two Ohms. The resistance between each of these pins and any of the other three will be infinite. The COM and NC pins will be shorted together (well under 1 Ohm). The NO pin will have infinite reistance to all other pins. Until you activate the relay, you won't be able to tell the differnence between the COM and NC pins.
Guessing from the layout of the pins shown in your picture, the coil pins are the two at right. This guess is based on the fact that there are two of them grouped separately from the others. Relays are sometimes used for their electrical isolation between their input (the coil) and their output (the switch contacts). As such, there is often a larger physical distance between these two sets of pins.
Flip the relay over and look at what is printed on the top. This will often tell you the voltage or current the coil requires to activate the switch, and what the switch is rated for.
You aren't going to be able to drive this relay directly from the digital output of a microcontroller. A simple low side NPN switch is usually the easiest way to control a relay from a digital output. There are many questions here already on that topic, so no need to repeat the details in this answer.