Here is the circuit diagram of Lamp Flasher using NE 555. As the name says the heart of this circuit is the timer IC NE 555. This circuit is operating from 230V AC mains. In this circuit, the timer IC is wired in such that it works as astable mutivibrator. This astable multivibrator circuit produces pulses for flashing the lamp. The duty cycle of the pulse can be varied by using the resistors R2 (47K) and R3 (10K). As the duty cycle changes the rate of flashing also changes accordingly.
The power supply for timer IC is half wave rectified output that is taken through diodes D1 and D2. The triac T1 (BT 136) is used to drive the load L1. The triac T1 is driven by the transistor Q1 (BC 548). The 1K resistor R4 is used here to limit base current of transistor Q1.
- Use a good quality PCB or common board to assemble this circuit.
- Use an IC holder for mounting the IC NE 555.
- If frequent changes in rate are needed, replace resistor R2 with a 100K potentiometer.
- Intensive care should be taken while dealing with this circuit since many parts of it are live with potential shock hazards.