This is with scope ground wire clipped on the power supply V- terminal. Test lead is on either wire on the limit switch and the signal never changes with the switch pressed. The average voltage agrees with the volt meter set to DC reading 7.12V. The noise is always present. Both switches show the same behavior, nothing changes when pressed.
Well, you've got rid of the 60 Hz hum at least. That's good. But the limit switches are already doing their jobs so you're not really chasing the problem as I see it.
However, what happens if you adjust the trigger level? Does the fuzz move up and down with it? Try setting trigger to an unused channel.
BTW: The fuzz isn't necessarily a problem. The scope is showing noise that is ignored/unseen/filtered by the controller.
Hello Evan. Thanks for the info. I did adjust the trigger up and down and park it dead center of noise. No change. It sits at that range at all times no matter what the switches do. Maybe this is a current type detector after all.
More than likely it is some noise on your line or system. The simple micro switch setup is just a current loop. Maybe driving some opto's on the main board. Opto's normally 10 Ma for full on. Like a 4n25 or CNY17-4, etc.
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Maybe the limit switch circuit is not that sophisticated and you just have a bad or noisy switching power supply
This is with scope ground wire clipped on the power supply V- terminal. Test lead is on either wire on the limit switch and the signal never changes with the switch pressed. The average voltage agrees with the volt meter set to DC reading 7.12V. The noise is always present. Both switches show the same behavior, nothing changes when pressed.
Well, you've got rid of the 60 Hz hum at least. That's good. But the limit switches are already doing their jobs so you're not really chasing the problem as I see it.
However, what happens if you adjust the trigger level? Does the fuzz move up and down with it? Try setting trigger to an unused channel.
BTW: The fuzz isn't necessarily a problem. The scope is showing noise that is ignored/unseen/filtered by the controller.
Hello Evan. Thanks for the info. I did adjust the trigger up and down and park it dead center of noise. No change. It sits at that range at all times no matter what the switches do. Maybe this is a current type detector after all.
Limit switches are simply beasts. Just need to know where the wiring goes is all. Without a wiring diagram you're doing far too much guessing.
One answer is to open up the boxes, meter it out and do a rough hand drawn diagram.
Sounds like a lot of screwing around for the sake of EMI. Just stick a differential xceiver on the line.
More than likely it is some noise on your line or system. The simple micro switch setup is just a current loop. Maybe driving some opto's on the main board. Opto's normally 10 Ma for full on. Like a 4n25 or CNY17-4, etc.