Simple Relay Based Lamp Flasher Circuit is good for indicators, warning lights and in anything that need attention.
Circuit uses relay, resistor, capacitor to blink light and does not need any complex parts.
It runs on 12V and is easy for beginners to learn electronics.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistor | 220Ω 1W | 1 |
| Capacitor | Electrolytic 2200µF 25V | 1 |
| Semiconductors | Relay 12V SPDT | 1 |
| Lamp 12V 5W | 1 |
Circuit has 12V SPDT relay, capacitor, resistor and 12V lamp.
When power is ON the capacitor charges through the resistor.
When voltage is high enough then the relay turns ON and the NC contact moves to NO by turning the lamp OFF.
The capacitor then discharges by lowering voltage to the relay coil.
When the voltage is too low to keep it ON then the relay turns OFF and NC contact connects again and the lamp lights up.
This repeats to make the lamp blink.
Formulas with Calculations:
Below are the formulas with calculations for Simple Relay Based Lamp Flasher Circuit
Blink speed depends on R1 and C1.
T = 0.693 × R1 × C1
where,
- R1 is 220Ω and C1 is 2200µF
T = 0.693 × 220 × 2200 × 10⁻⁶ = 0.34 seconds.
Lamp blinks about every 0.34 seconds.
Change R or C to change blink speed.
How to Build:
To build a Simple Relay Based Lamp Flasher Circuit following steps are required for connections:
- Collect all components like 12V SPDT relay, resistor R1, capacitor C1, 12V lamp.
- Connect one end of R1 to +12V and other end to relay coil pin.
- Connect capacitor positive to same relay coil pin and capacitor negative to other coil pin.
- Connect NO pin to coil pin linked to capacitor negative and to one side of lamp.
Conclusion:
This Simple Relay Based Lamp Flasher Circuit makes light blink using relay, capacitor and resistor.
It runs on 12V and changes R1 or C1 to change the speed.
Circuit is good for beginners to learn electronics and relay working.
References:
Recreate an inline 12 Volt Electronic Flasher unit for LED turn signals