In this instructable, I will show you how to make a bidirectional LED chaser. I built this to be a bike flasher, and this would be a very good application for this. If you are going to use it for a bike flasher, you are going to want to use the brightest LEDs that you can find. other wise it is still a cool light show type thing. this is a pretty easy circuit to make, so you should not encounter many problems.

Step 1:

First, you are going to need to gather the materials. all the materials are fairly common, and feel free to change the value of things if you want to experiment.

- one 555 timer
- one 4017 decade counter/ decoder
- two 1k resistors
- one 10 µf electrolytic capacitor
- two .1 µf ceramic disk capacitor
- six-eight 1N4148 diodes (number needed depends on the number of LEDs you use)
- one 10k trimmer (or potentiometer, but the trimmer was smaller)
- one eight pin IC socket
- one sixteen pin IC socket
- one SPST toggle switch
- four-six 3000 mcd red LEDs
- one nine volt battery snap
- a lot of jumper wires

Step 2: Connect the 555

In this circuit, the 4017 decade counter is fed by a pulses sent by a 555 timer. So it only makes sense that the first thing we do is wire up the 555.pin 1 to ground pin 8 to power, connect pin 2 and 6, connect pin 5 to ground through a .01 uf capacitor, conect pin 6 to ground through a 10uf capacitor, and connect pin seven to the wiper pin of the 10k pot/ trimmer and connect one of the pot's outside pins to pin 6, and the other to power. don't worry about pin 3 just yet.
hook up the ground from the 9v snap to the middle pin of the switch, and connect another wire to the outside pin, and connect it to the board for all the ground connections. connect the positive side directly. put a .01 uf capacitor from power to ground.

Step 3: Wire Up the Pot

Solder the trimmer (or pot if you are using that) with one outside pin to pin 8 through a 1k resistor (the resistor is not necessary but it helped a little with me), the wiper pin to pin 7 on the 555 and the other outside pin to pin 6 on the 555.

Step 4: Wire Up the Decade Counter

connect pin 8, 13, and 15 go ground. connect pin 16 to power, and connect pin 14 to pin 3 of the 555. The rest of the pins on the decade counter are going to be connected to the LEDs. Remember the order of the pins that the LEDs go to from the schematic.

Step 5: Wire Up the LEDs

Basically all you need to do with the LEDs is wire them in the correct order to the decade counter. the only thing is, you will need to wire 3 of the 4 LEDs to two of the pins from the decade counter, and must be connected to it through diodes so that electricity does not jump from one pin to the other. Connect the anode of the LEDs to the decade counter, and connect all of the cathodes, and connect them to ground through a 1k resistor. If you are using 4 LEDs, connect the first one to pins 3 and 5 through diodes on the decade counter. connect the second one to pin 2 and 1 through diodes on the decade counter. connect the third to pins 4 and 10 on the decade counter, and connect the fourth LED to pin 7 on the decade counter (you don't need a diode for this one.

Step 6: Finished

If you are going to use this as a bike flasher, you are going to need an enclosure for it, and a way to attach it to a bike. a project box from radio shack would probably work fine, and there are all sorts of ways you could attache it to a bike I would probably try a couple of zip ties first, but there are probably better ways to do it. If you have any sort of problems or questions, please leave a comment and I will try to help you out. Also please rate this instructable so I know how I did. Have fun!
P. S. When you turn it on, you will see the back and forth sequence, but it will pause briefly before starting over. this will not happen if you use 6 LEDs, but I feel the flashing affect makes it more visible.