This is a project that I completed sometime in September 2007. The main idea was to have a belt that I can wear that has LED lights all around it. These LED lights will light up one at a time and circle around me at a speed that I can control.
Another short video of the LED belt. This one shows how bright these little surface mount LEDs can be.
This is the LED Belt as it looks from far away. You can see I used an Altoids tin as the belt buckle. It was the only thing I had at the time and it just barely fit all of the components with the battery. The actual belt part is made from tubular webbing. The white dots you see are the actual surface mount LEDs. I had to melt holes in the webbing with an old soldering iron to get the LEDs to show.
Here you can see the switches and the plug. The large toggle switch is just used to turn the power on and off. The copper lever is attached to a potentiometer. The POT is used to control the timing on the 555 timer. This is what changes the rate at which the LEDs blink. If you turn the speed up too far the circuit will freeze and only one LED will stay lit. The plug is the part that attaches the LEDs to the main board. I used a plug here instead of just soldering the LED wires directly to the board so that I can use the LED portion of the belt for another project in the future or visa versa. This would also allow me to make several belts with different color LEDs and hook them all up to the same buckle.
This is what the bottom of the buckle looks like. I just used a regular buckle I purchased at REI. To attach the plastic buckle to the Altoids tin I just used hot glue. This part could use some improvements. The hot glue doesn’t hold very well and sometimes the Altoids tin will fall off. I have to keep re-heating the hot glue to re-attach it.
This is what the inside of the belt buckle looks like. Obviously the battery takes up most of the room. The small IC is the 555NE timer chip. The larger IC is a 4017D decade counter. The 555 timer controls the counter. Each of the 10 outputs of the counter control an LED. On the right side you can see the small 100K potentiometer.
I didn’t get a PCB printed out or anything. I was able to get this board for free from someone at school so I just used it. There was a lot of wiring that had to be done, but I think I found the most effective way to place the components considering what I had to work with. If I had a board printed I could make this whole belt buckle so much smaller. This is especially true if I use surface mount components.
This is a close up of the actual LED. I was able to find a lot of 100 surface mounted LEDs on eBay for cheap. They worked perfectly for this project. To get them in the belt, I soldered each LED to it’s own small, rectangular piece of PCB. Each PCB had a wire that ran from the anode on the LED to the decade counter. There is also a wire that goes from the ground inside the buckle, to each LED. They are all wired up in parallel.
To get the LEDs inside of the tubular webbing, I had to cut slits into the back of the webbing. After I cut the slits, I melted the edges with the soldering iron to keep them from fraying. I had to slide the piece of PCB into the webbing and then thread the wires through to the belt buckle end. I also used a needle and thread to sew the PCB in place. I think a dab or two of hot glue would help a lot as well. The thread isn’t holding as well as I’d hoped it would.
This is the schematic for the LED belt. You can see all of the components here. It’s really a simple circuit. The only thing that isn’t included in this schematic is the plug. It goes between the decade counter and the LEDs. The resistor, potentiometer and the capacitor are all just part of the 555 timer circuit. They determine how fast the LEDs will blink. I used a 100ohm resistor with a 10uf capacitor and a 100kohm potentiometer. These values work well together, but they can all change as long as they follow the timer formula. The potentiometer doesn’t really need that big of a range. I just thought it would give me some wiggle room.