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Help with anemometer circuit and PS2 mouse

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I am using a LM2197 to convert AC pulses to DC for displaying on an analogue meter. This works as expected, using a stepper motor as a pulse generator. I now want to use an old hacked Microsoft PS2 mouse to get one of its opto switches to work as the sensor, but have run into problems. I have powered up the mouse with 5V and ground, pins 3 and 4 on the male mini DIN plug, but can't get any output from either of the remaining two output wires on the mouse leads. Does the signal need amplifying, or can the raw opto pulses be tapped off directly?


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The outputs are open collector and need pullup resistors to 5V. See this page for more info on the PS2 protocols.


New Member
Anemometer from mouse opto switch

I have tried a pull up resistor from the collector to +ve, but no difference. It seems that the pulse output is very weak - should it be? I am expecting a chopper output pulsing from 0 to +5V which should be readily measurable. The mouse has a chip which may be affecting the output. Is a simple 741 op amp follower needed to boost the output from the opto chopper?


Mouse Modificaton


This article may be of some interest to you.

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