Converting D.O npn to pnp

[Alex LE Lim]

Hi, this is Alex here, I purchase a Beck GmbH Differential Pressure Transmitter 984M.5X1314b but later found out that the the digital out put is npn.
However I need a pnp DO.
Any option I can just change some transistor component to make the DO pnp?

 

[Pommie]

Do you mean you need it invert the output? Edit, and what is it feeding?

Mike.

 

[Alex LE Lim]

Yes. the output rating is 4...20mA/ 0..10V

 

[Pommie]

And, which do you need?

Mike.

 

[gophert]

You can place a 100 ohm resistor and 500 ohm resistor in series between your 18 to 24volt supply and the sense wire (NPN connection). This will create a output a "0" to 10v potential across the 500 ohm resistor. Make sure the 100 ohm resistor is connected to the more positive part of the circuit.

Then you can add a rail-to-rail differential amplifier (single chip) and connect The + input to Vcc and (-) input to other end of the 500 ohm resistor. Use resistors to set gain to 1.0.

The output will be 0-10v.

There are other ways with different resistor combinations and different gains. I'm sure you will hear more advice shortly.

 

[dr pepper]

I looked up that device, and I have an equivalent device by danfoss right here, the metal can is crimped & sealed theres no way to open it up without wrecking it, and even if you did it would be microsurgery to mod it.
What is the device connected to, if the 4-20ma receiver can be configured as active or passive there might be a way to get a npn o/p to work.
When you say npn, you mean the device sinks current?

 

[rjenkinsgb]

It appears to be this version, with both 4-20mA and a switching output:

https://www.beck-sensors.com/wp-content/uploads/Bedienungsanleitung%20984M_manual_3wire_display_switch_8.930.122-1.pdf

If it's just feeding a logic level input, use a pull-up resistor to the logic supply and invert the signal after that.

If it needs to control something like a relay, you need to add a PNP transistor or P channel FET.

eg. Use the "high side" circuit from this example, connected to the existing NPN output rather than a micro.
The "VDD" supply can be 5 / 12 / 24V etc. in this application, whatever is appropriate.

If you say exactly what is being driven and what supply, people can suggest appropriate devices and resistor values.