Grounding problems


I think I have a grounding issue I don t know how to solve. The basic problem the 5v signal from the masso is not triggering the a small relay to turn on and off my router. I am using the spindle CW signal from the masso.

The small 5v relay controls a solid state relay to turn on and off the router.
My main power-supply is 24 volts, I added a secondary 5v USB POWER SUPPLY for running my cooling fans.

When I added the small 5v relay to control the SSR I used the same 5v Power-supply which powers the fans.

When I measure input voltage to the small relay it is 5v between the +v and -v of the small relay.
When I measure the voltage between ground of the masso and the input signal I get 5v when the spindle CW is on.

When I measure the voltage between the relay -V and the signal input I get 0 volts which I think is the reason rely is not being triggered.

So I think the problem is no common ground between the small relay and the masso or the relay is bad.

I am wondering how to fix this . Get a proper 5v power supply, the masso is not chassis ground, not sure how to chassis ground it or the relay, finally would a 24v to 5v step down converter.

So how do I connect this small relay to the masso so the signal triggers the relay or should this work and I have a bad relay? I plan to replace it just in case.


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Staff member
You need to common all -ve connections of the power supplies that you are using. This establishes a signal reference point. There is no need to connect this reference point to "chassis ground."

Your "earth/chassis ground" common point should connect all your AC powered devices to the building earth.




Hi, Dhagen

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