Fine Control SuperBright LED Pulser

Four timing controls - 12V supply

Suitable for Halloween or Christmas props

Circuit diagram:

Fine Control Superbright LED Pulser


R1,R5,R12,R13___10K  1/4W Resistors
R2,R5___________10K  1/2W Trimmers or Lin. Potentiometers
R3______________47K  1/4W Resistor
R4______________22K  1/4W Resistor
R6_______________1K  1/4W Resistor
R7,R8,R9,R14___100K  1/4W Resistors
R10,R11__________2M2 1/2W Trimmers or Lin. Potentiometers
R15____________220R  1/4W Resistor

C1,C2__________100nF  63V Polyester or ceramic Capacitors
C3,C4___________22µF  25V Electrolytic Capacitors
C5_____________220µF  25V Electrolytic Capacitor

D1,D2________1N4148   75V 150mA Diodes
D3______________LED   Super Bright white (e.g. RL5-UV2030)

Q1____________BC337   45V 800mA NPN Transistor

IC1___________LM324   Low Power Quad Op-amp IC
IC2____________4093   Quad 2 input Schmitt NAND Gate IC


This circuit, designed on request for a Halloween prop, allows fine control of a pulsing Super Bright white LED. The four potentiometers or trimmers will set precisely: on, off, ramp up and ramp down time-delays respectively.
Ramp up and ramp down time-delays can be set roughly in the 1 - 15 seconds range, whereas on and off time-delays can range from a few seconds to about one minute.
A 12V battery or regulated power supply is required, provided it is reasonably stable. Total current drawing is about 25 - 30mA when the LED reaches maximum brightness.