I have a question regarding to the HX711, i have a load cell that its exitation voltage is between 9-12V, However if i connect all the wires to the HX711, including the VCC from the arduino, the 5V from the arduino wont be able to make the loadcell working, or i am wrong. I dont seem to find the answer anywhere thank you.
based on the data sheet of ur load cell and its current requirements
have u tried connecting the arduino to external supply and connect the hx711 to the vin pin?
Maximum operating voltage of the HX711 is 5.5volt.
Connecting it to Vin could release the magic smoke.
Just connect the HX711 supply to Arduino's 5volt pin, and the load cell to the chip's stable AVDD reference voltage.
A lower supply voltage on a load cell is just a lower output voltage.
Something that can be corrected in software.
I assume you're using a HX711 module, not a bare chip. Post a link.
Also post a link to the load cell.
Leo..
Wawa:
Maximum operating voltage of the HX711 is 5.5volt.
Connecting it to Vin could release the magic smoke.Just connect the HX711 supply to Arduino's 5volt pin, and the load cell to the chip's stable AVDD reference voltage.
A lower supply voltage on a load cell is just a lower output voltage.
Something that can be corrected in software.I assume you're using a HX711 module, not a bare chip. Post a link.
Also post a link to the load cell.
Leo..
SparkFun Load Cell Amplifier - HX711 - SEN-13879 - SparkFun Electronics this is the HX7511;
http://www.saithongelectric.com/index.php?lay=show&ac=article&Id=518670&; and this is the load cell;
I already have the load cell, the problem is that i am having a lot of problems hooking it up with a precision amplifier, and then giving that signal to my arduino; thats why i started looking into the HX711; and i was wondering if i could connect a HX711 module to my load cell. Thank you!
Yes, I think you can use your load cell with the HX711.
The wire colours also seem to match the Sparkfun board (not all load cell do).
Did you use the INA125 before.
Lots of people are having problems with this chip because there are several incorrect diagrams floating on the net.
Post a diagram/picture if you want to have another try.
Leo..
Wawa:
Yes, I think you can use your load cell with the HX711.
The wire colours also seem to match the Sparkfun board (not all load cell do).Did you use the INA125 before.
Lots of people are having problems with this chip because there are several incorrect diagrams floating on the net.
Post a diagram/picture if you want to have another try.
Leo..
Alright then, thank you, but that raises me a question, how can that work? Does the hx511 amplyfies the voltage vdd from the arduino and give it the load cell? I didnt use the ina, i used the ad624, i used the datasheet load cell configuration and didnt work, i dont know why the output is a negative voltage.
That Sparkfun HX711 board turns the not so stable 5volt Arduino supply into a stable 4.3volt supply for the load cell (AVDD).
A load cell is perfectly happy with that, although a lower supply is a lower load cell output voltage.
You have to calculate if the gain of the HX711 matches the load cell and what you want to weigh.
I think with the AD624 and Arduino's A/D, there is less room for error than with the HX711.
The AD624 (or INA125) need more supporting parts for accuracy.
Post a diagram of how you did connect the AD624.
Leo..
Hi,
I think the OP is worried about damaging the load sensor with incorrect voltage.
As long as you use an excitation voltage below the max rated it will be okay.
A load cell is just a group of resistors in a bridge configuration, lower excitation volts will just give you lower output volts.
The OP's cell is 3kg to 120kg, so I hope he is not expecting better than 0.1kg resolution.
Tom.... 
elmaco92:
Alright then, thank you, but that raises me a question, how can that work? Does the hx511 amplyfies the voltage vdd from the arduino and give it the load cell?
VDD (which is 5V) is still the same. What the HX711 does is amplifies (internally) the differential voltage from the sense wires, employs a 24bit A/D conversion, and then provides that value digitally to the Arduino. So the huge advantage here is that you're not forced to use the piddly 10bit A/D converter on the Arduino but instead get a value that's 16,384 times more precise.
elmaco92:
I didnt use the ina, i used the ad624, i used the datasheet load cell configuration and didnt work, i dont know why the output is a negative voltage.
That's just a matter of swapping either the two excitation or two sense wires on the load cell.
Chagrin:
VDD (which is 5V) is still the same.
As explained, load cell supply is NOT 5volt, but dropped and stabilised to 4.3volt.
The voltage on the sense wires is half of that.
Chagrin:
So the huge advantage here is that you're not forced to use the piddly 10bit A/D converter on the Arduino but instead get a value that's 16,384 times more precise.
Wow. Really?