Intro: NE555 and CD4017 Based LED Chaser With Photoresistor and Infrared Sensor
This is the modified version of a conventional LED chaser. We have modified this kit to respond to infrared and light.
The kit does work normally like a normal LED chaser kit. In addition to its obvious features, it has a photoresistor that allows you to change the speed of the chasing LEDs.
In the usual LED chaser, the speed is controlled with a variable resistor. In this kit, we have used a photoresistor to work as a variable resistor.
As the light falling on the photoresistor changes, the speed of the LED lighting sequence also changes. You can set the kit to receive infrared signals.If you turn on this feature, the LED chaser works only when you press a remote control close to the infrared receiver. You can use both infrared and photoresistor features at the same time.
How does it work ?
NE555 timer has been configured in astable mode and CD4017 works as a decade counter. NE555 can be powered directly or via BC547 transistor. To change power source, you can use the SPDT switch IR func. Output of NE555 has been connected to CD4017. For each pulse generated by NE555, CD4017 lights up LEDs in a sequence. A photoresistor has been connected to NE555. This has been used in place of variable resistor. When the light level falling on the photoresistor changes, the output frequency of NE555 changes and that consequently changes the LED running speed.
You can buy this kit at www.buildcircuit.com.au
Watch the video below to see how it works:
Step 1: Build the Kit From the Schematic
You can build the kit on a breadboard from the schematic. The full size schematic is available on this page.
You will need these components:
Most of the components are available at www.buildcircuit.com.au
1 x Bare PCB
1 x CD4017
1 x NE555
1 x 16 pin DIL socket
1 x 8 pin DIL socket
1 x LDR/photoresistor
1 x TSOP4838 or TSOP1838 infrared sensor.
1 x Screw terminal- 2 pin
1 x BC547
1 x BC557
1 x 1uF
1 x 100uF
1 x 1P DIP switch
2 x SPDT switch
1 x 2 pin screw terminal
10 x 5mm LED
3 x 5mm different color LEDs
6 x 1k Ohm resistor
2 x 470R resistors
1 x 470k Ohm resistor