Sn04-n 5-30v no replacement

Hello. I have a bad proximity sensor in my 130w CO2 Laser and I was wondering if I can replace the one I have which is rated 5-30v with a 10-30v. I can not find a supplier in the US.

The important thing is that it is a NPN device, this refers to the switching polarity (normally open vs. normally closed).

There are lots of inductive sensors around (3d printer suppliers typically have them) and so long as you match the polarity and voltage range you will be ok.

You might be able to match the form-factor or you may need to make a plate to fit it, with some adjustments of course.

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Thanks, so the voltage range needs to match (5-30v).

These may be a direct replacement:

New egg:Unique Bargains 4mm Inductive Proximity Sensor Switch NPN NO DC 5-30V 200mA 3-wire SN04-N -
Light Object: SN04-N Metal Proximity Sensor - LightObject | Professional Laser Cutters and Engravers Solutions

They are also on AliExpress although its url will not resolve.


Well, you need to match the voltage your machine uses… that’s almost always 5v if the sensor simply plugs into the controller board. It won’t be greater than the motor supply voltage (12 or 24v).

You can check this with a voltmeter or by tracing where the wires go. But most inductive sensors have a wide supply voltage range anyway, they all use a similar circuit internally, but come in many different shapes.

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Thank you Don! I’m gonna try aliexpress and see if they can do a fast shipping. Its probably gonna cost more than the part itself.

Hello, I ordered YAMIN brand from Aliexpress. It was supposed to be 5-30v, but I received OMCH brand 6-36v. I was wondering if they would work?

Do you have a multimeter? if so trace the wires to where they plug into the controller and check the voltage the existing unit gets.

I run a (very differently packaged) one of these sensors as a Z axis sensor on one of my printers. It also says 6v but has reliably worked from 5v for years. As I mentioned the actual (analogue) circuit all these units use is pretty common, you tend to loose range with lower voltages, but the sensitivity remains high.

So maybe just plug it in temporarily; don’t try homing etc, but move the unit and see how it behaves as you manually move it towards the target? Does the led on it work as expected? With enough range? and Reliably? if so you are probably good.


What @easytarget said…


I´m gonna check that voltage when I get home this afternoon and see how many volts Im getting. This is the literature that came in the box, but I can not read Chinese unfortunetly.

I see, below the first set of equivalent circuit diagrams; DC6-36V(5-30V),
But that PDF is horribly encoded and nothing have can translate it. Usuall Google translate and co. do a good job on this sort of document. Ho Humm.

Still; I’d take it as a good sign that the actual operating voltage range probably includes 5v.

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This is the voltage I am getting at the sensor when I switch the machine to on (23.74v). It seems to be working fine so far.

Need to do some engraving tomorrow to see how it behaves.

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