The circuit in Figure 1 uses LEDs rather than 4 lamps and is powered from a DC power supply or cells. The circuit uses a IC-555 (timer) configured as an astable multivibrator driving a power transistor.

The frequency is controlled by P1 in a range determined by C1, and the pulse duration is determined by R2. These components can be changed from 4.7 to 47 k. White bright LEDs are recommended, but depending on the application, you can use common LEDs of any color.


The power drain depends on the number of LEDs used in the project and also on the values of R4 and R5. These resistors can be increased if you don’t need high power or if you want to use common LEDs.


Figure 1
Figure 1


IC-1: 555 integrated circuit and timer

Q1: TIP32 PNP silicon power transistor

LED1 to LED4: White LEDs (see text)

P1: 1 NE) lin or log potentiometer

R1, R2: -10 k ohm x 1/8 W resistors, brown, black, orange

R3: 1 k ohm x 1/8 W resistor, brown, black, red

R4, R5: 47 x 1/8 W resistors, yellow, violet, black

C1: 1 µF polyester or electrolytic capacitor

S1: On/off switch (SPST)

B1: A 6 V or four AA, C, or D cells with holder

Other parts: PCB or solderless board, knob for P1, wires, solder, plastic box, etc.