Rigsby Machine

Complex, costly and performs a useless task.

The solar powered car darts from its starting position away from the lamp--only to be returned and repeat the cycle.

The runway, in its lowered position, closes a normally open micro switch--allowing power to a 12 volt, 50 watt halogen lamp.  This causes the solar powered car to race down the runway out of the light beam.  An Arduino microcontroller causes a servo motor to raise the runway, thus opening the switch, shutting off the light and causing the car to roll back to the starting position.  The runway is lowered and the process repeats.

Parts:

Solar Car--Amazon.com (less than $5.00)
Acrylic--estreetplastics.com
Servo HS 322--makershed.com
Arduino--makershed.com
Power supply for lamp--use a low voltage undercabinet supply of 50 watts or greater; regulated 12 volts supplies may not provide enough starting current to illuminate the lamp

Software:

#include <Servo.h>

Servo myservo;
void setup ()
{myservo.attach(5);
}
void loop ()
{
myservo.write(25);
delay (1000);
myservo.write (30);
delay (50);
myservo.write (35);
delay (50);
myservo.write (40);
delay (50);
myservo.write (45);
delay (50);
myservo.write (50);
delay (4000);
myservo.write (45);
delay (100);
myservo.write (40);
delay (100);
myservo.write (35);
delay (100);
myservo.write (30);
delay (100);
}

I cut a 12 inch long by 1 and 3/4 inch wide strip of 1/4 inch thick acrylic.  I attached a 12 inch by 3/4 inch by 1/8 inch strip of acrylic to the side.  I attached the servo horn to one end of this arrangement.

I added a "wall" to the other side, then discovered that the runway is too wide.  The car can turn sideways or even backwards!

The choice was either to cut new pieces of plastic and do this right or go for the quick fix. 

This was my first experience with Sugru (soft touch silicon rubber that moulds and sets permanently).  This stuff is great!  Squish it in your hands like clay, put the pieces together and wait over night.

Now the car can't turn around or get wedged in sideways.

Remove the servo horn from the plastic and screw it to the servo motor.

Screw the motor and servo horn assembly into the plastic runway.

Drill a 5/64 inch hole in the plastic opposite the center of the servo shaft.

Drill a 5/64 inch diameter hole in the 4 1/2 inch long (1 1/2 inch diameter) acrylic rod at the height opposite the center of the servo shaft.

This will accept a piece of 1/16 inch diameter stainless rod--the axle/bearing opposite the servo motor.

Turn the assembly upside down and secure the servo motor and acrylic cylinders to the base.

Solder 12 inch long (you may cut these down to make the project more neat) #22 stranded wires to the 50 watt halogen lamp (Westinghouse lensed spot, gu5.3 base--12 volt).

Drill two holes and secure the lever switch to a piece of 1/2 inch thick acrylic.

Solder wires--one from the halogen lamp, one to the power supply onto the normally open micro switch (this micro switch is rated for 5 amps; that's the minimum acceptable).

Drill holes in the base to accept screws that will secure the Arduino.

Using double sided tape, fasten the six volt battery pack to the base (screw the Arduino in place).

Solder the wires from the servo motor/battery pack and Arduino together.  Tape them with electrical tape to prevent shorting.

Use aluminum tape to secure the halogen lamp wires to the posts.

Use more aluminum tape to secure the halogen lamp power supply wires to the base.

CAUTION: KEEP OUT OF DIRECT SUN OR THE CAR WILL RUN AWAY!