LED or Lamp Pulser

Astonishing effect

4.5V supply

Circuit diagram:

LED Pulser


R1,R2___________4K7  1/4W Resistors
R3_____________22K   1/4W Resistor
R4______________2M2  1/4W Resistor (See Notes)
R5_____________10K   1/4W Resistor
R6_____________47R   1/4W Resistor (See Notes)

C1______________1µF   63V Polyester Capacitor

D1_____________5mm. Red LED (See Notes)

IC1__________LM358  Low Power Dual Op-amp

Q1___________BC337  45V 800mA NPN Transistor

Circuit operation:

This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc.
This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Q1 ensures current buffering, in order to obtain a better load drive.
R4 & C1 are the timing components: using the values shown in the parts list, the total period is about 4 seconds.