AlainB
Member
Hi,
I want to put back the 4 limit switches on my small CNC machine. The switches are Hall Effect Sensors. There is no part numbers on them but I figured out how they work and also that they can work at 5 volts. Red is 5 volts, black is ground and blue is the state of the sensor, 5 volts when not energised, 0 volts when energised by a magnet.
I want to use a single pin of the parallel port to input a change of state of any one of these sensors.
The schematic is the circuit I builded on a breadboard and it is working fine. The diodes must be there otherwise it is not working. The pull down resistor is also needed because there is a small voltage (leaking voltage??) at the cathode side of the diodes, around 0,02 volt and just touching with a finger is enough to trigger the output. I tested many values from 1K to 1 Meg and they all work well. I settle for a 100K resistor.
As I said, it is working fine but I would appreciate your opinion about this circuit. Would there be an easier way to do it, or a better part to use.
Putting the sensors in serie does not work unfortunately. It would have been a nice way of doing it.
Here is my little machine in action:
https://www.youtube.com/watch?v=OwjynFhSbWk
Alain
I want to put back the 4 limit switches on my small CNC machine. The switches are Hall Effect Sensors. There is no part numbers on them but I figured out how they work and also that they can work at 5 volts. Red is 5 volts, black is ground and blue is the state of the sensor, 5 volts when not energised, 0 volts when energised by a magnet.
I want to use a single pin of the parallel port to input a change of state of any one of these sensors.
The schematic is the circuit I builded on a breadboard and it is working fine. The diodes must be there otherwise it is not working. The pull down resistor is also needed because there is a small voltage (leaking voltage??) at the cathode side of the diodes, around 0,02 volt and just touching with a finger is enough to trigger the output. I tested many values from 1K to 1 Meg and they all work well. I settle for a 100K resistor.
As I said, it is working fine but I would appreciate your opinion about this circuit. Would there be an easier way to do it, or a better part to use.
Putting the sensors in serie does not work unfortunately. It would have been a nice way of doing it.
Here is my little machine in action:
https://www.youtube.com/watch?v=OwjynFhSbWk
Alain
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