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I need to generate a voltage signal to +5vdc on an input pin for a microcontroller. I have a functional circuit in place to handle a +24vdc input from a proximity sensor. Basically, this input pin on the microcontroller is held at 0vdc across a resistor and a zener diode is regulating the incoming voltage from the sensor. Since I need a positive voltage to be generated from the sensor, would that require a PNP or an NPN style sensor? Also, if I am using a proximity sensor and need the positive voltage signal to be generated while there is an object being detected, and the voltage signal to be near 0vdc when there is no object, would I require a NO or NC style?

Any help would be appreciated. Thanks.

PNP NO

Bill Sturm
Abbeytronics LLC

If I am thinking correctly a PNP proximity switch will have the positive output that you require. Also a N.O. output would be needed for the output to be "high" when its sensing an object and "low" when nothing is present. Hope this helps.

N.O. PNP.

Regards
cww

Thanks to all, very helpful.

Hi,

It's not really possible to determine if you need PNP/NPN based on the information you give so far. The reason is that it is not clear whether your microcontroller needs a current source or a current sink. Also, it sounds like a normally open sensor might work however it's a good idea to verify the microcontroller circuit against potential sensors' circuits. Terms like PNP/NPN and NO/NC do not sufficiently describe a device's input or output circuit.

If he is making it clear that he need a high input. i think its clear that his microcontroller is Sinking Input only. So PNP NO is perfect what he need.