Help identify the pressure sensor

[daisizhou]

There are 3 pressure sensors on the test air pressure detector,I took a picture separately
NB1 Looks like Sensym 926 SZ75153,metal shell,There are three wires in the interface.
NB2 I only see MICRO SWITCH USA,Number is K042
NB3  I only see MICRO SWITCH USA,Number is J1238 8914
Someone may know that this is a Honeywell model,I try to contact Honeywell service personnel,But gives the answer as shown below

I probably know this is the equipment produced in 1989,Can be used for medical related,Test air or oxygen dry gas,Pressure and flow
I hope people who know can tell me the model or the model used in place of it,Or its successor model

[daisizhou]

Help, friends who know their model please tell me, thank you

[amyk]

Look in here? https://archive.org/details/SenSym-Solid-StatePressureSensorsHandbook1994OCR

All custom products are assigned special part numbers, typically SZ#XXXX

Yours looks like LX18XXDZ series, but is a custom part.

[daisizhou]

Thanks for the help.
But I can’t open and browse this URLhttps://archive.org/details/SenSym-Solid-StatePressureSensorsHandbook1994OCR
I can't find the reason

[coromonadalix]

https://archive.org/download/SenSym-Solid-StatePressureSensorsHandbook1994OCR/SenSym-Solid-StatePressureSensorsHandbook1994OCR.pdf

a 96mb file

[daisizhou]

I'm very much obliged to you,Let me quickly find the model,It is indeed LX1820DZ
This is the voltage value corresponding to my actual test pressure

If you can help me find another 2 micro switches,That would be perfect

Thanks again for your help

[daisizhou]

I measured this air pressure module,I guess this sensor has no magnification function,It relies on an external operational amplifier circuit to amplify the output.This is the clue i know

[fzabkar]

Are NB2 and NB3 switches, or are they pressure sensors made by Micro Switch USA?

For example, here are two 3-pin Micro Switch pressure sensors, with signal conditioning (not yours):

https://pdf.dzsc.com/1PC/141PC01G_1077424.pdf
https://docs-emea.rs-online.com/webdocs/0025/0900766b80025ae3.pdf

The first sensor in this datasheet is a 4-pin Wheatstone bridge requiring an external constant current source:

https://stevenengineering.com/Tech_Support/PDFs/31PRSS.pdf

[daisizhou]

They are pressure sensors.But mark "micro switch" on the shell.
I checked the housing of this pressure sensor, the pictures are on NB2 and NB3
Did not see the exact specification model
I have viewed your PDF, but the shape is different.So I measured the entire circuit board, hoping to provide some clues

[daisizhou]

NB2, NB3 pressure sensor,They don’t seem to have a gain amplification function.Amplified by an external operational amplifier.
I guess it should be a bridge strain resistance
I hope to find its original record,Try to replace it or buy another model to replace it

[amyk]

180PC series looks like a close match...

[daisizhou]

180PC series looks a lot like,But only 3 lines of output,NB2 and 3 are 4-wire output.I think it should be a differential signal

[fzabkar]

Here is an application circuit for a pressure sensor using a current source for biasing the Wheatstone bridge:

https://www.notwired.co/datasheets/te/signal_conditioning_for_meas_pressure_sensors.pdf

This is the circuit I traced on a Western Digital hard drive with a 4-pin barometric pressure sensor:

Code: [Select]

                                                                     VCC
         ___                                                          +
      .-|___|--.                                     U25 /|           |
     _|        |__                                      /+|------.   .-.
    ' |   ||   |  '                           .--------<  |      |   | |
    | '---||---'  |               Wheatstone  |         \-|--.   |   | |
    |     ||      |                  bridge   | pin3     \|  |   |   '-'
    |             |                          / \             |   | R19|
    |             |       R20               /   \            |   '----+
    |      /|U26  |      ___               |     |           |        |
    |     /-|-----+-----|___|---------.   .-.   .-.          |       .-.
    +----<  |            ___          |   | |   | |          |       | |
    |     \+|-----+-----|___|-----.   |   | |   | |          |    R49| |
    |      \|     |               |   |   '-'   '-'          |       '-'
   .-.          .-+-.     R28     |   |pin4|     | pin2      |        |
   | |          |   |             |   '----+  U7 +----.      |        |
   | | R113    .-.  |             |        |     |    |      |       ===
   '-'         | | --- C14        |       .-.   .-.   |      |       GND
    |       R37| | ---            |       | |   | |   |      |
    |          '-'  |             |       | |   | |   |      |
    +-->|-->    |   |             |       '-'   '-'   |      |
    |           '-+-'             |        |     |    |      |
    |   D5        |               |         \   /     |      |
    v            ===              |          \ /      |      |
                 GND              |           |pin1   |      |
 amplified                        |           |       |      |
 pressure                         |           |       |      |
  output                          |           '-------)------+
                                  |                   |      |
                                  '-------------------'     .-.
                                                            | | R56
                                                            | |
                                                            '-'
                                                             |
                                                             |
                                                            ===
                                                            GND

U25 is the current source while U26 is a differential amplifier.