After our attempt at using the measuring tape to convert linear motion to rotational and drive the motor, we decided to look at something different. Using wheels to turn motors.
Once we knew we wanted to used wheels to run motors, we decided to make a car out of it.
We used 2 DC motors of 200 rpm and 2 steppers. All of their shaft were connected to small wooden wheels which were then connected to larger wooden rings. We used safety tape to ensure that the wheels don’t slip but roll.
The open circuit(OC) voltage and the short circuit(SC) current of the motor are as follows –
200 rpm DC motor – OC voltage – 7V, SC current 0.24A
Stepper motor – OC voltage – 35V peak, SC current 0.1A
We then mounted a board of 64 LEDs onto the chassis. Each motor was used to light 2 rows of LEDs. In case of the stepper, each coil lit one row. Each of the stepper coils and the DC motor outputs were passed through full bridge rectifiers so that we always got a positive voltage irrespective of which way the wheels rotated. The rectifiers were soldered to a perf board and mounted below the LED board.
Below is a video of the car working.