Hi,
I use 8951 to make a simple lift. P0,P1,P3 as input port,and p2 as output port.there are 6 dc motor have to be controlled, so I use multiplexer & data latch. output from d-latch is conected to the Rb of the transistor, and the coil of the relay(used to changed the directions of the motor) is conected to the colector. the emitter is conected to the ground.

first it seems work very well. but when i want to check the voltage accross the motor, suddenly the motor stop rotating. I try again, every time I want to check the voltage, the motor stop rotating. it also happen if i touch the motor with my finger, or i conected 1 of the motor terminal with open cable just like antena
then I check the output of the d-latch, i found the data is change from 1 to 0.

why this is happen? and how to solve this problem??



best regards,

ridvvan


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