In this instructable, we will be showing you how to construct a LED Dimmer circuit that runs on an adjustable timed loop using a potentiometer, a 555 timer and other basic circuit components. We first obtained the idea for this project from another instructable that made an LED strip controlled by a dimmer switch, found here: https://www.instructables.com/id/LED-Strip-Control-With-Dimmer-and-Audio-Pulsing-Ci/. This project was incredibly helpful in understanding how the potentiometer could work as a dimmer switch. For our purposes, however, we want to set up the potentiometer as a timer switch that automatically controls the length of time it takes for the LED strip to fade in and out. Hope you find this helpful!
Step 1: Acquire Your Components.
R1 560 Ohm resistor
R2 10 kOhm potentiometer
R3 10 kOhm potentiometer
R4 82 kOhm resistor
R5 1 kOhm resistor
R6 100 kOhm potentiometer
R7 100 kOhm potentiometer
R8 22 kOhm resistor
R9 1 kOhm resistor
R10 100 kOhm resistor
C1 470 uF capacitor
C2 470 uF capacitor
C3 470 uF capacitor
C4 1000 uF capacitor
C5 .01 uF capacitor
D1 1N4148 switching diode
T1 P2N2 NPN transistor
T2 N-channel mosfet
Step 2: Set Up the Circuit on a Breadboard
Step 3: Test the Circuit Using an Oscilloscope
When the circuit is finished and all put together, you should connect your circuit to an oscilloscope to see that the output wave is similar to the one shown above. Connecting one lead of the oscilloscope to ground and the other to the positive output terminal the LED strip will be connected to in the next step.
R2 adjusts the fade out time of the wave.
R3 adjusts the fade in time of the wave.
R7 adjusts the oscillation amplitude of wave, affecting the range of brightness of the circuit.
R6 adjusts the DC offset, alternating the range of voltage passing through the LED strip.