In this project, we make an important circuit involved in the majority of control circuit if you have a small signal Output Such as Microcontroller or sensor and you want to make a switch for 220 v device for you will use an electromagnetic relay
Requirements :
Battery 12v & 1.5 volt or adaptor
Resistors : pot1k ohm & 0.5 k ohm &120 ohm
Zener 5V:
Transistor Bc547
Relay 5 volt
1A Diode
breadbord
lets do the circuit :
Circuit explanation:
Once you close the switch the current will go throw Voltage Divider 1 k ohm pot this pot will control the current that will supply the base of the transistor control transistor sensitivity, the small base current makes the transistor switched on and the current go throw relay from the battery to collector-emitter track a 100-ohm resistor will protect transistor biasing from getting high to protect collector current from reach breakdown value 5v Zener circuit protection, to make maximum input signal is 5v value, a 120-ohm resistor protect relay and transistor.
Input signal should be:
Current (100uA- 2mA)
voltage( 1v to9v )
link for transistor basics
link for download circuit
https://drive.google.com/file/d/1WjjGvSVDwbXvEBn5lkX7qvCL7TuoAoiJ/view?usp=sharing
feel free to ask me any question:
Gmail: eng.darwishelectronics@gmail.com