In this instructable, I take a radio controlled car and convert it to a friction powered illuminated car--with ultracapacitor energy storage. You pull the car along the floor and the led on top comes on. The one farad (not microfarad) capacitor (under $4.00) keeps the light on for half an hour or more.

Step 1:

Start with a radio controlled car--one where the wheels stay engaged with the motor. Some of the cheapest cars have a slip arrangement in the gearbox for changing direction. We need a vehicle which is either tank like (left side on or right side on) or one with geared drive wheels and proportional steering. I've suggested one from Amazon.com that works.

Step 2:

Remove the cover and the lid to the battery container.

Step 3:

Remove the springs from the battery container.

Step 4:

Separate the car by removing screws so that you can access the motors.

Step 5:

Notice that two wires go to each motor assembly from the electronic unit (green, yellow and red, blue).

Step 6:

Cut the motor wires from the electronic assemly (radio receiver) and save the receiver for a future project.

Step 7:

Drill 1/8 inch holes in the battery compartment and clip out one of the battery separation walls.

Step 8:

Bring the motor wires through the holes and refasten the housing to the wheel assembly.

Step 9:

Create a diode bridge (see schematic in step number one). This allows voltage generated by the motor assembly (dc motors act like generators when turned) to always come out in a predictable fashion, regardless of which way the motor (now generator) is turned. I use a diode bridge for each motor assembly so that they will feed the capacitor and led rather than each other.

Step 10:

Solder the motor leads to the input of the diode bridge (the place where head and tail of diodes meet).

Step 11:

Insert two pieces of double sided foam tape to the ultracapacitor.

Step 12:

Stick the ultracapacitor into the battery compartment and bring positive and negative leads from the diode bridges to the capacitor.

Step 13:

Prepare to insert the led to the roof. I tried to drill through an existing "light assembly," but the drill bit caught and spun the assembly off into some unknown corner of the garage (this is why I wear goggles--you can never be sure when something strange is going to happen).

Having lost the light, I designed and printed a "light bar" with a 3d printer.

DO NOT ATTACH LEDS OR ANY SMALL PARTS IN A WAY THAT THEY CAN COME LOOSE IF THIS TOY IS TO BE USED BY A SMALL CHILD.

Sorry for "shouting," but this is important.

Step 14:

Drill holes in the roof and attach your led assembly to the roof. Bring the led wires to the capacitor. Put electrical tape around the diode bridges; we don't want things touching and shorting out.

Step 15:

Secure all the parts and give it a test run.

You will have to pull it a few times to charge the capacitor--then the light will stay on for quite a while (actually will glow for a couple of hours).