This project can be attached to the front of the shirt pocket of children, be used as bicycle indicators , or can be fitted with the wall clock in your home.
TECHNICAL DESCRIIPTION AND WORKING:-
This project has been developed and successfully tested OK in TV Engineer Technical Lab.
This is an easy and cheap electronic project, which is now a days very popular among the childern. It produces amazing lights in the darkness of the night. You can use LEDs in multiples of two, though we have given below a project of 8 LEDs [light emitting diodes]. You can attach it in front of your shirt pocket or use as a bicycle indicator or any other way. This project is specially very attractive during night.
Here LEDs work as semi-conductors, which require very low voltage to glow. The LEDs are one kind of diodes and current passes through LEDs, only when there is forward bias. During forward bias, the anode is positive as compared to cathode. When there is reverse biasing current does not flow.
This circuit is one kind of running multi vibrator and is also known as switching circuit. This has two stages. In the first stage T2 [BC148] operates, while T1 [BC148] remains off. As a result four Red LED D5,D6,D7,D8 glow. After sometime TR1 starts operating and T2 remain OFF. In this stage the other four Green LEDs D1, D2, D3 & D4 glow. This cycle continues.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT:-
- Check all the components as per the circuit.
- Check collector, base, emitter of transistors while soldering.
- Check +ve & -ve terminal of capacitors.
- Check +ve & -ve terminal of LED while mounting.
- Check for Dry soldering as well as short circuit.
LIST OF COMPONENTS
R1,R2 68K 2
R3,R4 820 Ohm 2
C1,C2 22 MF/16V 2
T1,T2 BC148 2
LED GREEN D1,D2,D3,D4 4
LED RED D5,D6,D7,D8 4