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Cheap Ball Mouse

Mouse
Mouse

Cheap old style ball mouse. PS/2 interface.

Top Removed
Top Removed

Top removed from the mouse, the ball fits in the gap in the centre. The slotted discs are visible which contact the ball & move relative to the surface the mouse is on.

PCB
PCB

PCB removed from the shell. Pairs of IR LEDs & Phototransistors make rotary encoders with the slotted discs. The microswitches read the mouse buttons & wheel.
IC in the centre interfaces with the PC over a PS/2 connection.

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Logitech Cordless Ball Mouse

Top
Top

This is an old legacy wireless mouse from Logitech. This uses a ball rather than optical technology.

Bottom
Bottom

Bottom of the mouse, showing the battery cover & the mouse ball.

PCB Bottom
PCB Bottom

Top removed from the mouse, showing the PCB inside. The smaller PCB on the left supports the microswitches for the buttons & mouse wheel.

Switches
Switches

Closeup of small PCB showing the microswitches & the IR LED & phototransistor pair for the mouse wheel encoder.

Main PCB
Main PCB

View of main PCB, with interface IC lower right. Pair of quartz crystals provide clocking for the transmitter & internal µC.
Battery contacts are on lower left of the PCB. At the top are the IR pairs for the X & Y axis of the mouse ball.

Encoder Pairs
Encoder Pairs

Closeup of the pairs of IR LEDs & phototransistors that make up the encoders for X/Y movement of the mouse, together with the slotted wheels in the mouse base that rotate with the ball. Steel wire around the smaller PCB is the antenna.