Simple 12V Lamp Flasher Circuit using IC LM317

This Simple 12V Lamp Flasher Circuit using IC LM317 is a cool project to make 12V lamp blink.

This circuit is not only for indicator or warning light but also for car or decoration light.

IC LM317 usually controls the voltage but here it work like oscillator for blink.

It can handle 1A, so lamp up to 12W is OK.

Blink happen because capacitor charges and discharges makes lamp ON-OFF regularly which looks cool.

Circuit Working:

LM317 IC is usually adjustable voltage regulator but here it work like oscillator using resistors and capacitors on ADJ pin.

When power is ON capacitors C2, C3, C4 charge through resistors R1, R2, R3.

When voltage is ON capacitors reach set level with LM317 changes the output voltage.

This make makes 12V lamp turn ON-OFF again and again.

Blink speed depend on values of R1, R2, R3 and C2, C3, C4.

Cycle repeats and lamp blinks in rhythm.

Below are the formulas with calculations for Simple 12V Lamp Flasher Circuit using IC LM317:

Blink rate uses RC time constant.

T = 0.7 × (R1 || R2 || R3) × (C2 + C3 + C4).

R1||R2||R3 = (10k || 10k || 10k) = 3.33kΩ.

C total = 10µF + 10µF + 10µF = 30µF.

T = 0.7 × 3.33kΩ × 30µF = 70 ms.

So lamp turns ON-OFF every 70 ms to about 14 Hz.

To build a Simple 12V Lamp Flasher Circuit using IC LM317 follow the below steps for connections and assembling of the circuit:

Put all parts from diagram together.
Connect IN pin of IC1 to 12V DC through switch S1 and filter cap C1.
Connect OUTPUT pin of IC1 to lamp L1 which this gives the flashing voltage.
Connect ADJ pin of IC1 to resistor network R1 to R3 and timing capacitors C2 to C3 that set blink rate.

Simple 12V Lamp Flasher Circuit using IC LM317 is an easy and efficient circuit.

It change resistor or capacitor values to make flash faster and slower.

Circuit is good, cheap, simple and parts are easy to find.