Contents
Can I use NPN transistor as PNP?
Answer: NPN and PNP transistors are interchangeable if you remember one simple rule: A bipolar transistor is essentially two back-to-back diodes with the base being the common connection.
How do you calculate NPN and PNP?
Connect the positive lead of the multimeter to the Base (B) of the transistor and connect the negative lead to the Emitter (E) of the transistor. If it is an NPN transistor then meter should show a voltage drop between 0.45V and 0.9V. If it is a PNP transistor, then it should display see “OL” (Over Limit).
Why NPN transistor is preferred over PNP?
So the correct answer is that n-p-n transistors are preferred to p-n-p transistors because electrons have higher mobility than holes and hence high mobility of energy.
How to convert NPN output to PNP output?
As you’ve surmised, if you need a SOURCE (PNP) input, you just need a pull-up resistor to 24V – but you need to bear in mind that the polarity is then reversed, which you can easily change in the PLC programming. If you can’t do that, then you could add two resistors and a PNP transistor to convert the output to SOURCE.
Can a NPN output turn on a coil?
Using NPN outputs and switch contacts between ground and an input or coil means shorts to ground can turn things on instead, which is obviously rather dangerous with industrial machinery.
Can a PLC be wired to only PNP input?
The PLC however is wired to receive only PNP type input as some of the Input ports are wired as PNP. Can this sensor output be converted to PNP type by connecting a pullup resistor (tied to +24 VDC) ?
What kind of resistor do I need for PNP?
Use a 2W resistor, at least, if it’s 470R & higher power for lower values. The industry standard is that everything uses switched positive, so PNP output sensors. It’s a basic safety principle, as then any wiring damage most likely shorts power and blows fuses.