Basic Relay Activation Through Simple Techniques

Assalam o Alaikum , Today I want to share my final assignment of Relay Activation through Simple techniques Using Transistors , Heat Sensors or Wireless Transmission. Hope you find it Informative.

Experiment 1 :

Energizing relay through Transistor :

Description:

In this Simple arrangement , we have got a transistor(BD 139) which is turned on by the signal on its base . When it is turned on, coil connected to it is energized and is responsible for the connection between common and normally open contact of the relay. Note that common is given 220vAC so that whenever there is a signal at the base of the transistor, connection between common and normally open contact derives any 220 volt load (e.g. Lamp in this case).

Experiment 2:

Modification for Digital Signals:

Description:

This is the modified circuit for operation at 5vdc (digital). We have used a comparator (LM324) and appropriate resistors to set this circuit operation at 5v. Whenever a signal is slightly greater than 5volt at the positive input of the comparator, its output will go high (24v) that will derive the transistor and energize the coil, in turn the Lamp would be energized as well.

Experiment 3:

Infrared Transmission:

Description:

This is the modified circuit for Infrared transmitter and receiver. Transmitter is connected with 4.7k resistor and Receiver is connected with reverse polarity (Cathode with Vcc) as compared to transmitter with 20k resistance. Its range can be modified by changing the value of the resistors. When there is no obstacle between the transmitter and receiver 0v (approx.) is received at receiver side. When there is anything in between, Receiver gets 24 volts across it, which turns on the transistor and coil is energized. As a result, Contact occurs between normally open and common of the relay and the lamp is ON.

Experiment 4:

Heat Sensor:

  

Description:

This Circuit contains LM35 which is a temperature sensor having ratings of 10mv/Celsius. Also, we have used non-inverting amplifier to increase the voltage for further use. So, when we heat LM35 temperature increases and in turn voltage at the positive terminal of amplifier increases. Rf and R1 set the gain of the amplifier and output voltage at A is received. Here, for example we have used a comparator with appropriate setup so whenever the temperature goes above 5 volt we receive a 24v signal at the comparator output that can further be used.

Experiment 5:

Stepper Motor:

 

Description:

This is stepper motor internal circuit. First of all we find the sequential wires that rotate the motor in correct and continuous direction. Then, connect them in sequential way like this circuit. Whenever you give transistors continuously voltage at their (either left to right or right to left) , the stepper motor will take steps according to the sequence. One transistor is responsible for a single step when turned on.

Experiment 6:
Stepper Motor Program (PLC):

A Stepper motor is to be operated in following pattern.
1- Data 0001 has to be rotated.
2- Data should be rotated every 3 seconds.
3- Rotation should be either left or right.
4- Program should have Master Start Stop control.
5- Stop button should reset all outputs.

I/O Table :


 

Ladder Diagram :

Description:

The Ladder diagram works in following pattern.

When you press the start button the output RUN is activated and the process is started. Input I0.3 initiates a timer T37 of 3 seconds. Input I0.0 selects the data movement to be either left or right. Input I0.1 moves in the data either 0001 or 0011. The combination of the timer and the left right control output is responsible for rotation of data in the desired direction. Master Stop resets any data present in the outputs.  

--Copyright : Muhammad Shahzaib S. Qureshi--