Schematics > Motor, light and power control > LED Chaser
LED ChaserI don't know why, but people like blinking lights. You see LED chasers
everywhere, in TV shows (Knight Rider), movies, and store windows. This
schematic is my version of a simple 10 LED chaser. There is no 555 timer used
because at my local electronics store they are over $4 Cdn. Instead, an
oscillator made up of two sections of a 4011 NAND gate is employed. This chip is
very inexpensive and extremely common.
Schematic
Parts
| Part |
Total Qty. |
Description |
Substitutions |
| R1 |
1 |
1 Meg 1/4W Resistor |
|
| R2 |
1 |
100K Pot |
|
| R3 |
1 |
1K 1/4W Resistor |
220Ohm if using blue LEDs |
| C1 |
1 |
0.1uF 16V Ceramic Disk Capacitor |
|
| U1 |
1 |
4011 CMOS NAND Gate |
|
| U2 |
1 |
4017 CMOS Counter |
|
| LED1-10 |
10 |
LEDs Of Any Colour |
|
| MISC |
1 |
Board, Sockets For ICs, Knob For R2 |
|
Notes:
1. Use R2 to adjust the "chase rate".
2. You may need to use a lower value resistor if you wish to use blue LEDs.
Try 220 Ohm.
3. You can also use incandescent lamps instead of LEDs. Use transistors to
drive them by connecting the base of the transistors to each of the outputs of
the 4017 through a 1K resistor. Connect one end of the lamp to the positive
supply. Then connect the other end to the collector of the transistor. The
emitter then goes to ground. Depending on the lamps, you may need power
transistors that are heat sinked.
4. C1 may be replaced with a larger value for a slower "chase rate".
5. If you have problems with weird circuit behavior, try replacing R1 with a
33K resistor, and increasing C1 to 1uF.
6. If you plan to use this circuit in your car, be warned that in some areas
it is illegal to have red, blue or yellow flashing lights unless you are an
emergency vehicle.
Title: LED Chaser
Source: www.aaroncake.net
Published on: 2005-02-03
Reads: 424
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