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Electronic circuits that use the 555 Timer

555 Timer Circuits

555 Timers are fun and a great way to start learning electronics

UP/DOWN FADING LED Circuit


A Circuit that fades an LED on and off.

Overview

These two circuits make a LED fade on and off. The first circuit charges a 100u and the transistor amplifies the current entering the 100u and delivers 100 times this value to the LED via the collector-emitter pins. The circuit needs 9v for operation since pin 2 of the 555 detects 2/3 Vcc before changing the state of the output so we only have a maximum of 5.5v via a 470R resistor to illuminate the LED.

Schematic

Fading LED Circuit

Video

This video walks you through building this circuit using a breadboard.



Parts List

1x - NE555 Bipolar Timer
1x - LED (Red) 1x - 470 Resistor (1/4W)
1x - 33K Resistor (1/4W)
1x - 100F Electrolytic Capacitor (16V)
1x - BC547 NPN Transistor
1x - 9V Voltage Battery

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