Planetary Motion Depicted by the Orrery

The project uses flashing LEDs to represent the planets in order to simulate the mechanically scanned planetary motion known as the Orton Orrery.

The Orrery is based on a single PIC16F627 microcontroller and only 6 planets from Mercury to Saturn are available in order to keep with 18th century Orrery tradition. The rotating assembly consisting of LEDs and PIC and the motor are the two electrical parts of the Orrery. They are being powered from separate sources wherein a small plug-in mains power supply provides power to the motor and onboard coin cells provide power to the spinning part.

To avoid the need for a motor speed controller, the display is maintained to be synchronized with the motor rotation by including a phase locked loop (PLL) in the PIC code. The current consumption of the rotating part is a little more than that of the PIC and the duty cycle is very low despite all of the LEDs. This signifies that coin cells can satisfactory power the LEDs and PIC.

A 20cmx20cm box frame is used to house the Orrery. Mounted centrally to the back board is the motor.

Rest of the project