MK1 Steel router build log 1500x800x200

[Doddy]

So there is some type of voltage regulator on the inputs circuit.

Agreed - our results tally.

http://www.everlight.com/file/ProductFile/EL817.pdf

If the 817 is preceded with an italic "L", then its the Liteon LVT-817. The 1024 is just the date-code. These are all pretty much the same.

I tested my 6-36 vdc NPN proximity switches in 24vdc and 12vdc situation
Hooked up a 4.7 k output load on black vs blue wire.
this to test inline resistance of the proximity switch by voltage divider calculation.

It looks like i have +/- 9.4k inline resistance in the output circuit of the proximity switch.

http://www.ekt2.com/pdf/14_PROXIMITY_INDUCTIVE__8BX.pdf

You don't say if the sensor is On or Off. What's the actual voltage with 24V applied across the supply, measured with a 4k7 pull-up, in both On and Off states? (I'll measure mine in the morning anyway). I'd expect the output voltage to be sat at 24V "Off" and near-as-dammit 0V "On".

Do you feel i can there for not go past 12 vdc to protect the opto`s against :
24volts PSU - 9.3volts input pin voltage = 13.7 volt reverse ?

Maybe we are trying to solve a non problem, please look at line 3 and tell me what you think.

It becomes a non-problem provided that there are no pull-ups to the supply voltage to the sensor. Once you have the sensor input floating to 24V (which you'll only have with a pull-up, for example if you wanted a 24V control circuit) then you're breaking the spec on the data sheet, and will likely damage the optocoupler.

3. External power supply input: 12-24V. Equiped with anti-reverse connection function.

I simply read that that there's reverse-polarity protection on (or around) the LM317 regulator. There is nothing on the optos to protect them (this would be an easy mod to the board to support 24V signalling).

I do think this is a non-problem by avoiding 24V switching levels.