Variable speed focus motor controller.

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Powered focusers are very nice to use. No 'jitters' or 'jumps' in the image as you are focusing your telescope and you can get very fine motion. Building one yourself is fairly simple and the costs are about $35. The board I've designed here works around a 555 circuit to do the speed control which turns on and off an IRF530A FET. It is designed to power a standard DC gearhead motor. The speed is selected by adjusting a 50K potentiometer. Two DPDT on/on push button switches enable the motor, one for each direction. Runs off of a standard 9v battery The circuit is not powered until a button is pressed for longer battery life. Each switch utilizes 5 of its 6 terminals. The motor side of each switch is labeled E, C and D for 'Enable', 'Common' and 'Default'. The Common terminals connect to the motor (labeled MTR). The E terminal is connected when a button is pressed and the D terminal is connected when a button is not pressed. SW3 on the layout is the other half of each button wired together in parallel. The SW3 side of the buttons powers on the 555 circuit when pressed while the ECD side provides reversible power to the motor. Here is a link to a PhotoShop document you can use to mask and etch the needed board if you are not going to use perf-board. Back to Ozzzy's Astronomy page