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2024-05-27 5:09 pm
@azslab Is there a magnet in the machine that the sensor pictured passes over?
First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, 360, fairly knowledge in PC plus numerous MPU's & MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.
Topic starter
2024-05-27 5:21 pm
@zander No magnet, it detects anything ferrous. I actually use a steel washer mounted on a nylon threaded rod on one axis and a dome head nut on another axis. You can buy NPN or PNP ones depending on how you wire them. The good thing about them is they can be mounted at a right angle to the metal reference point so there is no way of smashing into anything. If they're mounted on a moving part of the machine you only need one per axis. This is as opposed to using one at each end and having the ferrous reference point moving.
2024-05-27 5:40 pm
@azslab Ok, not sure what that is since no magnet is involved.
First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, 360, fairly knowledge in PC plus numerous MPU's & MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.
Topic starter
2024-05-27 5:47 pm
Voila
2024-05-27 5:47 pm
@azslab Can you tell if there is a magnet inside the 3 wire sensor?
First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, 360, fairly knowledge in PC plus numerous MPU's & MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.
Topic starter
2024-05-27 6:01 pm
@zander I think they work with a coil inside. When a ferrous object passes near it triggers the gate of its transistor. Hence why you can buy NPN or PNP ones. It was a few years when I installed them so not fresh in my mind. But excellent pieces of kit.
2024-05-27 6:18 pm
@azslab Ok, so an electro magnet, that explains the extra wire, ground, power, and sense. Ground and power should be external from whatever board you use, and the ground should also be connected to the board Gnd with the 3rd wire connected to an analogue or digital pin depending on voltage. It will appear in sketch the same as a button.
First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, 360, fairly knowledge in PC plus numerous MPU's & MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.
AZSLAB reacted
2024-05-27 6:33 pm
@azslab I spoke too quickly, that device is more likely using some sort of circuit to detect the change in the coil's field since the ferrous material will disrupt the magnetic field thus disrupting the electrical field.
First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, 360, fairly knowledge in PC plus numerous MPU's & MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.
Topic starter
2024-05-27 6:58 pm
@zander That makes sense. I was strongly advised to use them rather than mechanical switches on the CNC forum I use. I had actually bought the switch seen in my little video before knowing about the best way of making home / limit circuit control for a CNC machine. The mechanical switch had been unused in a drawer untill I used it for this experiment. Now I'm aware of mechanical switch bouncing I can see why I got the advice at that time albeit without a technical explanation.
Chris
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