220V LED flasher
Category: Analog Circuits
Designer: RANA MUHAMMAD ADNAN KHALIL
Notes
This circuit is designed and simulated in Proteus 7.10. This is very amazing LED flasher circuit from 220Vac or 110Vac. The working of this circuit is given below. 1. In this circuit, the DIAC D2 of 35V is used for flashing LED. 2. Diac is a device which is used as a bidirectional switch at certain voltage level. 3. In this circuit 35V diac is used, which means it conducts whenever its terminals reaches near 35V in either direction. 4. Diode D1 is used as half wave rectifier. 5. The flashing frequency depends upon resistors R1, RV1 and capacitor C1 (as RC time constant). 6. The Capacitor is fixed at 22uF100V, and also resistor R1 is fixed at 100Kohm, so the only varying part is RV1 between 0 to 100Kohm. 7. The human eye can detect frequency upto 20Hz (approx) and can't detect 50Hz, the circuit is make according to this concept. 7. The flashing trick is that we charge capacitor C1 at very slow rate so that it can charge in 5 cycles per second (at around 10Hz) so that the frequency is visible, and charging rate can be changed by varying RV1 (changes flashing frequency). 8. When the capacitor reaches near 35V the diac starts conducting and LED D3 will glow and capacitor discharge at faster rate then charging. 9. When capacitor discharges the LED will turn OFF and diac again waiting for capacitor to charge at 35V and this continues. 10. The wattage of resistors R1 and RV1 should be greater than 1W. Application: 1. The concept of this circuit can be used to detect and measure frequency. 2. The concept of this circuit can also be used to detect dimming of voltages. Precautions: 1. THIS CIRCUIT IS DANGEROUS, BECAUSE THERE ARE LIVE VOLTAGES AT THE R1 or RV1, SO BE EXTRA CAREFUL WHILE IMPLEMENTING THIS CIRCUIT. 2. USE SAFETY GLOVES BEFORE USING OR TURN ON THIS CIRCUIT. 3. DON'T MAKE AND RUN THIS CIRCUIT ALONE. THERE SHOULD BE SOMEONE NEAR TO OBSERVE YOU WHILE YOU ARE WORKING ON THIS CIRCUIT. 4. IT IS RECOMMEDED TO USE SERIES LAMP, UNLESS YOU CONFIRM YOUR CIRCUIT WORKING PROPERLY. Before practical you can download these files and perform simulation experiments for more understanding.