Sorry, have not noticed your prev. post.

I do not have any commercial load cells. it is a film made of gold and chromium deposited on metal surface and acts like strain gauge. this is measured with wheatstone bridge (preferably quarter bridge).
...
Is my approach is right ?

So you have one resistor that varies with the applied force. You have to measure it's deviation from initial resistance.
Add 3 resistors to make a bridge, maybe some sort of variable resistor to balance the bridge - and you can attach your 4-wire cable to it.
This bridge is less sensitive than most commercial load cells - because only 1 of 4 resistors varies. And it has non-linearity, of course. But for a given task it may be relevant.

 

Sorry, have not noticed your prev. post.

So you have one resistor that varies with the applied force. You have to measure it's deviation from initial resistance.
Add 3 resistors to make a bridge, maybe some sort of variable resistor to balance the bridge - and you can attach your 4-wire cable to it.
This bridge is less sensitive than most commercial load cells - because only 1 of 4 resistors varies. And it has non-linearity, of course. But for a given task it may be relevant.

Thank you for the response . I am planning to use quarter bridge circuit. Can you suggest any commercially available load cells for checking the circuits in breadboard ?i prefer 3 wire load cell

Thanks

 

I am planning to use quarter bridge circuit. Can you suggest any commercially available load cells for checking the circuits in breadboard ?

Have not got you. Load cell, as I see it in my personal practice, is a complete sensor: it transforms applied force into the bridge's dis-balance.
Look an example PC22-10.
There is a rather complicated circuitry inside (not a simple bridge), we have a pair of wires for excitation and a pair of wires as differential output.
If you want to use a single strain resistor, you have to decide at least 2 tasks:
- fix your sensitive element (resistor) on a part that will accept the force
- insert that resistor in a bridge or half-bridge
Then you can use your sensor with the strain gauge amplifiers, ADC and so on.
Once more: I do deal with the commercial load cells. I cannot be an expert with the homemade sensors.

 

Can you pls suggest a set of hardware required for this conversion and pros and cons if possible

adc the output and send it over a serial bus of your choice.

 

There is a rather complicated circuitry inside (not a simple bridge)

Most of them are a bridge, including the one you referenced.

The signal is typically rather wake and some amplification is used, unless you use high resolution adc.

 

A fairly inexpensive module that I have used (for a different purpose, however) is HX711. It is a 24-bit adc with a PGA on board, two channels.

It can deliver about 16 - 17 bit of effective resolution without much care.

I used it a couple times to measure very low resistance: you can see my experience with it on my blog.

It is, in case you want to know, specifically designed to work on weight scales (strain gauges).

 

HX711

It is good, really!
Still I use Texas Instruments, ADS1231 has fixed gain and is very easy in use. And it has very low noise and drifts.
AD7730 (and a lot of similar from AD) is good to, but the use is more complex.

Thanks to dannyf I've got info about the HX711. It is cheap, easy to use, popular and so on. It resembles me my favorite ADS1231 - no internal registers. And it has a switch to cut off a bridge consumption - very good!
But the characteristics are unavailable. AVIA Semiconductors... So noises and stability is doubted.

 

there is a chinese-version with slightly more data but not enough.

My experience with it is that it can deliver fairly good (noise-free) resolution without much care but suffers from opposite tempco coefficients for the A and B channels so any ratiometric design would be out of the question for this chip.

Other than that, it is a fun chip to play with.