This post shows a Simple Lamp Flasher Circuit using IC LM395 to flash a lamp ON and OFF
LM395 IC is a strong power transistor which works like a switch.
It needs only few parts and can handle high current.
It has safety features like heat and current protection.
Even if design is simple it works well for signal or for decoration of lights.
Circuit Working:
Parts List:
| Component | Quantity |
|---|---|
| Resistors (All resistors are 1/4 watt unless specified) | |
| 100k | 1 |
| 10k | 1 |
| 150k | 1 |
| 470k | 1 |
| 47k | 1 |
| Capacitor | |
| Electrolytic 10μF 25V | 1 |
| Semiconductors | |
| IC LM395 | 1 |
| Transistor 2N2222 | 1 |
| Incandescent Lamp 12V 1A | 1 |
In this circuit transistor Q1 works like oscillator and makes pulses again and again.
R1, C1 and R3 control how pulses happen.
When power comes C1 charges through R1.
When C1 is full Q1 turns ON and C1 discharges and makes a pulse.
This pulse goes to base of IC LM395 through R2 and turns LM395 ON.
LM395 lets current go to lamp L1 and then lamp lights up.
As C1 charges and discharges the lamp keeps flashing.
Circuit uses 12V DC power to work.
Note: We can add 1A fuse in positive line if we want.
Formulas with Calculations:
To make lamp flasher circuit use these formulas:
T = 0.693 × (R1 + R3) × C1
where:
- R1 is 100k ohm
- R3 is 150k ohm
- C1 is 10uF
T = 0.693 × (100k + 150k) × 10uF
T = 0.693 × 250k × 10uF = 1.7325 sec
Now:
f = 1 / 1.7325 = 0.577 Hz
So lamp flashes about 0.577 times per second.
How to Build:
To build a Simple Lamp Flasher Circuit using IC LM395 follow the below mentioned steps for connections:
- Take all the circuit parts as shown in above diagram
- Base of IC1 connect to collector of Q1 through R2
- Collector of IC1 connect to +12V
- Emitter of IC1 connects to one side of lamp L1
- Other side of lamp L1 goes to GND
- Base of Q1 connect to emitter of IC1 through R1
- Positive of C1 connects to base of Q1 and negative to GND
- R4 connects to +12V in series with R5 and R5 other end goes to GND
- R3 one end goes between R4 and Q1 emitter and other end goes to emitter of IC1
Conclusion:
This Simple Lamp Flasher Circuit using IC LM395 is easy, but strong and is good for blinking lights or warning.
This circuit is simple to build and great for learning.
It is perfect for hobby and beginner use.