I cannot control the transmitter with the XTR101 IC

Thread Starter

memedin

Joined Dec 24, 2022
30
0-5 V to 4-20 mA linear conversion from voltage to current signal transmitter, this is the circuit I want to make.

Materials used in the circuit:

  • XTR101
  • BAT249
  • BD243
  • Level transmitter

I am setting up the circuit, I get 5 V at the output without connecting the level transmitter. When I connect the level transmitter, I can't get 5 V and I can't see 4-20 mA. What could it be for?
 

Attachments

ericgibbs

Joined Jan 29, 2010
18,865
hi M.
Without you posting a diagram, means I would have to draw the circuit diagram.

It would be quicker and easier if you drew the diagram, then I would do my best to help you.

E
 

sghioto

Joined Dec 31, 2017
5,391
The schematic is similar to this, my sensor has 3 legs,
How's that going to work, the schematic shows a 4 wire bridge type sensor?
A 4 to 20 ma transmitter requires a load resistor normally at 250 ohms. This creates a 1 to 5 volt output depending on the current through the loop.
Is the board you have designed for a 3 wire or 4 wire sensor?
1673561047028.png
 
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sghioto

Joined Dec 31, 2017
5,391
Here's the schematic from what I can figure. I suspect C4 is a zener diode and R is the series resistor not seen in the photo blocked by Q1. Not sure what those 2 components labeled T1 are they look like resistors.
I'm assuming the 3 wires red, black and white are from the sensor. The red and black show connected across the zener diode and the white connected to input 3 but nothing connected to input 4.
It would appear this board is designed for a 4 wire sensor very similar to your schematic in post #5.
1673572715989.png
 
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Thread Starter

memedin

Joined Dec 24, 2022
30
Here's the schematic from what I can figure. I suspect C4 is a zener diode and R is the series resistor not seen in the photo blocked by Q1. Not sure what those 2 components labeled T1 are they look like resistors.
I'm assuming the 3 wires red, black and white are from the sensor. The red and black show connected across the zener diode and the white connected to input 3 but nothing connected to input 4.
It would appear this board is designed for a 4 wire sensor very similar to your schematic in post #5.
View attachment 285131
The sensor I use is 3 legged.
 

ericgibbs

Joined Jan 29, 2010
18,865
hi M,
You have to make the input a 4 wire. A full Bridge, your sensor is only a Half Bridge.
Add the two 1K 0.1% resistors to Pin 4.
Add the 250R across the output B1
Do you follow, OK.?
E
Redo1.gif
 

ericgibbs

Joined Jan 29, 2010
18,865
hi,
Look at this image,
This is what you have to do, add the resistors in order to make the half bridge into a full bridge.
The XTR must have a differential signal from the sensor and the resistors in order to work correctly.
The low value 47R potentiometer is to give a zero output setting from the bridge.
E
EG57_ 459.png
 

Thread Starter

memedin

Joined Dec 24, 2022
30
hi,
Look at this image,
This is what you have to do, add the resistors in order to make the half bridge into a full bridge.
The XTR must have a differential signal from the sensor and the resistors in order to work correctly.
The low value 47R potentiometer is to give a zero output setting from the bridge.
E
View attachment 285141
ı will connect the signal leg of 47r potentiometre to IN- feed?
 

ericgibbs

Joined Jan 29, 2010
18,865
hi.
The wiper of the Pot goes to pin #4 of the XTR
The White wire of the sensor to Pin #3
E
If the polarity of output voltage of the XTR is reversed, you will have to change over the Pin# 3 and pin# 4 connections.


Redo1.gif
 

Thread Starter

memedin

Joined Dec 24, 2022
30
hi,
I don't understand what you are asking and why.
What is the problem.???
E
Hello,
Whe I plug in my signal terminals, I cant get a signal. I think the problem of this is that it cannot feed the XTR101 due to the 78m05 regulator.
There is a 78M05 regulator in the circuit, ı guess thats the problem, what should ı use instead?
 
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