This is my instructable for the creation of adult sized flashing shoes. It was actually a project I was building for a friend that wanted a pair of shoes that would light up. Being as electronics is my hobby and line of work I decided I would make him a custom pair.
Initally I was simply going to use a force resistive sensor, a couple cheap comparator chips and run the on/off output of the comparator into a 555 trigger to send out a burst of flashing. The plan was to calibrate the sensor to trigger only during heavy G loading (ex. Foot contacting the ground) to keep the flashing from constantly triggering when the person was simply standing still.
Due to the cost of FSR sensors, and the bulky size of my homemade ones I had to scrap the idea. I needed a solution that would come in under $30 and work reliably (I also tried pedometer circuit hacking...but was very unsatisfied with the results). Due to my budget and time constraints using a simple one time programmable PIC was also out of the equation (could not find a cheap reliable sensor for flash triggering without using a FSR).
Final solution, let someone else do the hard work and simply hack up a cheap pair of kids flashing shoes to work with my larger design! This would be inexpensive, very reliable, durable, and would not eat up a bunch of my time. Prefect!
Step 1: Find Your Donor
Find a suitable flasher shoe donor. The one I finally settled on was a pair of kids winter boots. I used these because they had a the brightest LED's, I liked the flashing pattern and all the electronics were contained in the fleece linner top...nothing was embedded into the rubber sole making it much easier to remove.
Step 2: Start Hacking
Hack it all apart. I chopped into the boot to liberate all the electronics I needed. I was trying to save the boot to give away to a thrift store or the like once I had what I needed out of it, but the damage I needed to cause put an end to that plan. Inside you should find a small microprocessor with button cell battery connected to the LEDs. In my case all the electronics were sealed in a small acrylic box filled with epoxy...no chance on a battery change ( not easily), but nearly indestructible!
Step 3: Mod It
Modify the internals. The shoe triggered 4 LED's in a nice sequential patteren. One of the outputs on the internal chip must have been damaged when I was removing the unit as only 3 LEDs were active once I got to testing the unit. Perfect for our case as only 3 LEDs per shoe were needed. The LEDs the shoe came with were small, but very fragile (thin leads) so I replaced them with larger LEDs. The current rating is very similar between the two lights so we risk no damage to the internal circuity.
To extend the wiring I used an old Cat5e cable I had laying around, stripped the casing off, and use the twisted pairs for most of my tinkering work. Close to the cheapest wire I have found! I soldered the wire extensions on, heat shrinked all connections, then doubled the wires over the micro and held them in place with a little bead of hot glue to act as a strain relief. Once I tested the unit to make sure everything was functioning as normal I took a large section of clear heat shink and totally cover the micro controller. We are now ready for installation!
Step 4: Install
Install your modified creation! I had planned to install the LED is the sole of the shoe, but ended up using the lace holes to mount them. In this manner the flashing was quite a bit more visible in direct light, and the sequential pattern of the LEDs running down the shoe looks really cool in my opinion. The battery/circuit was slid into a small slit in the side of the tounge and due to the ample amount of padding in this shoe you cannot at all feel it once on your foot. Pictured is a bit of shoe lace magic I had to preform in order to lace the shoes up correctly, luckly this shoe has small loops to run the laces thru that I could use to free up the lace holes for LEDs.
The leads off the LEDs are bend 90 degrees, double heat shinked for durability, and then pressed into the lace holes. The holes are tight enough that no glue was needed to keep them in place. I had not taken the extra effort to clean the wiring up totally as I was unsure if the owner of the shoes would like the placement of my LEDs. I left enough slack in the wires to change up the design as he saw fit.
Step 5: Testing
With everything installed I tapped the shoes onto the ground a few times and was very satisfied with how they worked. Once I tried the shoes on I found they trigger with almost every step (on my carpet flooring, they should trigger 100% of the time outside on pavement).
The only real problem with the shoes that I see is that they are crazy bright! Walking down a dark hallway makes for a very interesting experience! With the LEDs cycling 3 times per side in about 2 seconds you get a very strobe like effect!