Thursday, December 24

Brightness Control for small Lamps by IC 555


Switch-mode driven 1.5V bulbs
Portable unit - 3V battery supply

Parts:

P1________________470K Linear Potentiometer

R1_________________10K 1/4W Resistor
R2_________________47K 1/4W Resistor (See Notes)
R3__________________1K5 1/4W Resistor

C1_________________22nF 63V Polyester Capacitor
C2________________100µF 25V Electrolytic Capacitor

D1,D2___________1N4148 75V 150mA Diodes

IC1_______________7555 or TS555CN CMos Timer IC

Q1_______________BD681 100V 4A NPN Darlington Transistor

LP1_______________1.5V 200mA Bulb (See Notes)

SW1_______________SPST Switch

B1__________________3V (Two 1.5V AA or AAA cells in series, etc.)

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