A Simple Lamp Flasher Circuit that uses relay technology is really useful in many situations like for indicators, warning lights and anything that needs to grab attention.
This circuit cleverly uses a relay, a resistor and a capacitor to make the light blink without needing complicated electronic parts that could make things tricky.
It works with a 12V power supply making it a great option for beginners who are starting to learn about electronics.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistor | 220Ω 1W | 1 |
| Capacitor (Electrolytic) | 2200µF 25V | 1 |
| Relay | 12V SPDT | 1 |
| Lamp | 12V 5W | 1 |
The above circuit diagram includes a 12V Single Pole Double Throw SPDT relay, a capacitor, a resistor and a lamp that runs on 12 volts.
When power is supplied to the circuit the capacitor C1 starts to charge up because it is connected through the resistor R1.
As the voltage on the capacitor increases and hits the level needed to turn on the relay coil the relay gets activated.
This activation switches the normally closed NC contact to the normally open NO position.
As a result the lamp turns off since it loses its connection to the ground.
At the same time the charged capacitor begins to discharge, which lowers the voltage going to the relay coil.
When this voltage drops below what the relay needs to stay on the relay turns off, going back to its normally closed position and allowing power to flow back to the lamp which lights up again.
This whole process keeps repeating creating a blinking effect as the lamp turns on and off.
Formulas with Calculations:
Below are the formulas with calculations for Simple Relay Based Lamp Flasher Circuit
The blinking rate depends on the values of R1 and C1.
The approximate time delay T can be calculated using the RC time constant:
T = 0.693 × R1 × C1
where,
- R1 is 220Ω
- C1 is 2200µF
T = 0.693 × 220 × 2200 × 10⁻⁶
T = 0.34 seconds per cycle
The lamp will flash at an interval of approximately 0.34 seconds.
Changing the resistor or capacitor value will alter the blinking speed.
How to Build:
To build a Simple Relay Based Lamp Flasher Circuit following steps are required for connections:
- Gather all the components mentioned in the above circuit diagram
- Connect one end of resistor R1 to positive supply of 12V and the other end of resistor connect to COIL pin of 12V relay
- Connect a positive of capacitor C1 to COIL pin of 12V relay and negative of capacitor connect other COIL pin of the 12V relay.
- Connect N/O pin to terminal of relay COIL which is connected to the negative of capacitor C1 and to one terminal of lamp load.
Conclusion:
This Simple Relay Based Lamp Flasher Circuit creates a blinking light using a relay a capacitor and a resistor.
It runs on a 12V power supply and you can easily change the flashing speed by tweaking the values of R1 and C1.
This circuit is a great way to get started with learning about electronics and how relays work.
References:
Recreate an inline 12 Volt Electronic Flasher unit for LED turn signals
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