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You have an overload on the mV scale. Switch to DC volts to see what voltage you have.Micheal_Leo said:... but multimiter is not displaying anything ...
Baluncore said:You have an overload on the mV scale. Switch to DC volts to see what voltage you have.
Please provide the circuit you are using with all resistor values.
What is the resistance of the strain gauge?
yes half supply,i do not have 120 ohm resistors,.can i use 100+ 22 ohm resistors in series?Baluncore said:The resistor ratios must match.
Is that a pair of 220R = 220 ohm resistors in the top row, making half the supply ?
Below left is another 220R resistor, but it should match the 120 ohm strain gauge, so it also makes about half the supply. Then mV range should work.
Replace the bottom left 220R with a 120R resistor.
Why are you using such a high bias voltage? Maybe switch to a single 1.5V AA battery to avoid wasting so much power...Micheal_Leo said:please find the attached schematic diagram
berkeman said:Why are you using such a high bias voltage? Maybe switch to a single 1.5V AA battery to avoid wasting so much power...
Yes.Micheal_Leo said:yes half supply,i do not have 120 ohm resistors,.can i use 100+ 22 ohm resistors in series?
THE Attached results are mv and Voltage , please see this , i will connect it to hx711, these results before force not applied , please guide that should i consider mv or voltage to transfer it to arduino to study stress in that part.the PLA printing material not follow hookes law i have applied force on part for testing so little bending is present in partBaluncore said:Yes.
i see change in mv but also my finger burn accidently comes near to strain gauge , strain gauge get hot during this phenomena mv voltage out of control like it kept increasing ,Baluncore said:I do not know where you are going with this.
Do you see any change in the mV reading when you flex the strain gauge?
If you see only a small change, you may need to adjust the 22R resistor, to better balance the bridge, to get closer to a zero difference voltage output. Then you can use more gain in the hx711 without the amplified DC offset hitting the voltage limits.
The differential voltage output that now goes to your mV meter, will go to the hx711 differential inputs, INA+, INA-. The bridge drive voltage will probably come from the hx711, AVDD and AGND.
Too much voltage to the bridge circuit.Micheal_Leo said:... i see change in mv but also my finger burn accidently comes near to strain gauge ...
thank you very much, hx711 supplying voltage is 5v, i shoud use dc power supply and give 1.5v to both hx711 and wheatstone brdigeBaluncore said:Too much voltage to the bridge circuit.
Too much bridge current.
Too much heating of the strain gauge resistance.
The gauge resistance is temperature dependent, so balance changes.
Use less voltage, use AVDD and AGND from the hx711.
i have voltage regulator so have intention to supply 3v to both bridge and hx711Baluncore said:The hx711 can run on between 3 and 5 V. If you use the same voltage as your controller, the digital signal voltages will all match without problems.
The hx711 has a regulator that provides the voltage drive to the bridge. The voltage is set by the ratio of R1 and R2 on the hx711 reference PCB design in the data sheet. Use what it has now, or select resistors that set the bridge voltage to somewhere between 1.2 and 2.5 volts.
If you increase the bridge drive voltage by 1%, you get a 1% increase in the difference voltage from the bridge, for the same strain. That is a problem with accurate 24 bit measurements.Micheal_Leo said:i have voltage regulator so have intention to supply 3v to both bridge and hx711
please can you suggest best A-D converterBaluncore said:If you increase the bridge drive voltage by 1%, you get a 1% increase in the difference voltage from the bridge, for the same strain. That is a problem with accurate 24 bit measurements.
The A-D converter is ratiometric. It uses the bridge drive voltage as a full-scale reference, and so automatically corrects for variations. That is why it has the voltage regulator for the bridge drive on the same chip as the A-D converter. If you do not use that on-chip regulator, you will get scale errors in the strain readings. Read the data sheet, and follow the advice.
You cannot afford the best.Micheal_Leo said:please can you suggest best A-D converter
i have try to do it , somehow it work as i expected , the video attached , secondly the follwoing hx711 amplifier i have , i am very much confused how to attach wheatstone bridge with this hx711 , please need your guidanceBaluncore said:You cannot afford the best.
Use the hx711, because it is available, cheap ($2), and comes mounted on a PCB.
There could be several reasons for this issue. One possibility is that the strain gauge is not properly connected to the multimeter or the circuit. Make sure all connections are secure and the correct settings are selected on the multimeter. Another possibility is that the strain gauge is damaged or faulty, in which case it will not produce accurate readings. It is also important to check if the multimeter is functioning properly and if the batteries are charged.
If your multimeter is not displaying any readings for the strain gauge, first check if the multimeter is set to the correct range and if the leads are properly connected. If the issue persists, try using a different multimeter to see if the problem lies with the instrument. If the second multimeter also does not display any readings, then the strain gauge may be damaged and needs to be replaced.
Yes, the type of strain gauge can affect the readings displayed on the multimeter. Different types of strain gauges have different resistance values and require different settings on the multimeter. Make sure to refer to the strain gauge's datasheet for the correct settings and compatibility with your multimeter.
Inaccurate readings on the multimeter can be due to a number of factors. One possible reason is that the strain gauge is not properly calibrated. Make sure to follow the manufacturer's instructions for calibration. Another reason could be external factors such as temperature or electromagnetic interference. It is important to use the strain gauge in a controlled environment to get accurate readings.
The best way to troubleshoot issues with your multimeter and strain gauge circuit is to follow a systematic approach. First, check all connections and make sure they are secure. Then, check if the multimeter is set to the correct range and if the strain gauge is properly calibrated. If the issue persists, try using a different multimeter or strain gauge to isolate the problem. If all else fails, consult the manufacturer's instructions or seek assistance from a professional.