A 12V single lamp flasher circuit is a special electronic setup designed to turn a lamp on and off repeatedly creating a cool flashing effect.
This circuit is simple and strong making it perfect for flashing 12V lamps which are often used in cars.
You can find these circuits in different places like turn signals, warning lights and fun decorative lights.
The design we are talking about uses a 12V lamp flasher circuit that has a BC557 transistor and an IRF530 MOSFET.
It works by charging and discharging a capacitor which controls how long the lamp stays on and off.
Circuit Working:
Parts List:
| Component Type | Specification | Quantity | Notes |
|---|---|---|---|
| Resistors | 6.8k 1/4 watt | 1 | |
| 220k 1/4 watt | 1 | ||
| 22k 1/4 watt | 1 | ||
| Capacitor | Electrolytic 100μF, 25V | 1 | |
| Semiconductors | MOSFET IRF530 | 1 | |
| Transistor BC557 | 1 | ||
| Diode 1N4002 | 1 | ||
| Switch | SPST | 1 | |
| Lamp | 12V incandescent lamp | 1 | |
| Power Source | Battery 12V | 1 |
In this post when the circuit is turned on capacitor C1 starts charging through resistor R2.
As the voltage on the capacitor goes up, it eventually reaches a level that turns on the base emitter junction of transistor Q1.
Once Q1 is on it allows C1 to discharge through resistor R1.
This action pulls down the gate of transistor Q2.
When Q2 is activated it acts like a switch letting current flow through the lamp L1 making it light up.
As C1 keeps discharging the voltage at Q2s gate drops causing Q2 to turn off.
This makes the lamp go out and the whole process starts over again.
The speed of the flashing depends on how fast C1 charges and discharges, which is affected by the values of R2 and C1.
Also, the circuit can get its power straight from the car battery.
Formulas with calculations:
The formulas with calculations for Simple 12V Single Lamp Flasher Circuit is mentioned below:
Time constant for capacitor charging:
T = R * C
where,
R = R2 = 220k, C is C2 = 10μF = 0.00001F
T = 220,000 * 0.00001
T = 2.2 seconds approx
Total period of the flashing cycle:
Total period (T) = 0.693 * (R2 * C2)
T = 0.693 * (220,000 * 0.00001)
T = 15.246 seconds approx.
Flashing frequency:
Frequency (f) = 1 / T
f = 1 / 15.246
f = 0.066 Hz approximately 4 flashes per minute
How to Build:
To build a Simple 12V Single Lamp Flasher Circuit following connections steps must be followed for designing your own circuit:
- Gather all the components as mentioned in the above circuit diagram
- Connect the collector of transistor Q1 to one end of resistor R1 and other end of resistor to GND.
- Connect the base of transistor Q1 to negative of capacitor C2 and positive of capacitor to one end of resistor R3 and other end of resistor to drain of transistor Q2
- Connect emitter of transistor Q1 to positive supply
- Connect capacitor C1 positive to the junction of transistor Q1 emitter and diode D1 and the negative of capacitor is to GND.
- Connect one end of resistor R2 between base of transistor Q1 and negative of capacitor C2 and other end of resistor to GND.
- Connect gate of transistor Q2 between collector of transistor Q1 and resistor R1
- Connect the drain of transistor Q2 to one end of resistor R3.
- Connect source of transistor Q2 to GND.
- Connect L1 12V lamp and S1 switch from the positive of +12V battery and negative of battery to GND.
Conclusion:
This 12V single lamp flasher circuit is easy to build, affordable and can be used in many ways.
It shows how transistors and MOSFETs work together to create a flashing effect.
You can change the resistor and capacitor values to make the light flash at different speeds depending on what you need.
This circuit is great for car lights, alarms or even for fun decorations making it a useful way to learn about timing circuits.
References:
Recreate an inline 12 Volt Electronic Flasher unit for LED turn signals