Circuit Lake

The Telescope Focus Controller was designed to allow computer control of the telescope focus position through a serial port. It also allows manual control through clockwise and counter-clockwise buttons on the telescope’s keypad. To turns the focus shaft of a telescope, The project use stepper motor to do it. The project consist of microcontroller ATmega8 as main processor, MAX232A for serial communication, and DS18B20 temperature compensation of focus position.

Michael Lutton, the project designer, explained that the controller can accept the Celestron Ultima 2000 drive base focuser output. It will respond to the clockwise and counter-clockwise voltages and drive the stepper motor accordingly. The CW and CCW input connector should be a 2-conductor 3.5mm mono audio connector.

The controller able to drive a 12 V unipolar stepper motor. The maximum step rate is 200 steps per second. The motor should have at most a 1-degree step size. The stepper motor connector shall be a 6-conductor modular jack. Other features including ability to measure its temperature and an external temperature with a resolution of 1 F. Temperature could be used to compensate the focus position if the external temperature sensor is attached to the telescope optical tube.