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we use two line tracing sensors [...][...] when we common the ground of the two supplies (5v and 24v) the volt on the microcontroller becomes 7v and may reach 9v (7v is enough to make our microcontroller damaged)The problem happened when we common the two grounds of the two supplies so how we can solve this problem, how we can eliminate the noise to don't make the microcontroller damaged?
How it works : sensors are connected to 24v and with regulator 7805 we connect the MC to 5v the gnd is common for all the circuit as we see.when sensors sense an object it will output 15v so we can't use 15v as an i/p to our MC so we use a transistor and connected it to 5v so when the two sensor sense an object it will output 15v so transistor will be on so the i/p to the MC will be 0 (GND) and when the two sensors don't sense any object the output will be 0 so transistor becomes off so the i/p to the MC will be 5v..the problem here when the GND of the two sensors connected with the GND of the MC the noise of these sensors will rise the 5v to 7v and may be 9v so how we can eliminate the noise effect. as we can't separate the two grounds to make the MC able to read sensors o/p.
What's the advantage of the transistor over the voltage divider? Less current? Less components?
i had tested the transistors output and they are correct 100% when sensors sense an object the o/p will be 0v and when no object the o/p will be 5v ,and i said before that the problem isn't in the transistors
the problem found in the GND connections and the supply for the MC not the i/p to it's pins that comes from the two sensors because the supply must be 5v after connecting the GNDs of the circuit (24v and 5v) the supply of the MC becomes 7v and may be higher ..