Need help finding an electronic component

[Linux-SWAT]

Hi,

I need to find a digital hang hook scale circuit board.
While there's plenty of cheap pre-made models available like the ones in the picture, I need to buy naked ones where I can electronically read the weight from.

 

[rygD]

Instead of a smart ass comment ("I found a variety of components in the thing that I keep all mine in, so maybe check your own storage"), I will say that the pic with the is cute.

I can't offer any real help with this, but I will do a search.

 

[T.T.]

I'm not sure if you'll find one that has exactly what you're looking for up front, but you may be able to open one up to see if there's anything you can interface to.
I know that even cheap harbor freight calipers have a data output, so you might get lucky taking a cheap scale apart and poking around it's board.


Edit: I did do a quick search on load cells that can do tension or compression, but most of the ones that came up were $600 and up, and I can't imagine you want to spend that. But, you could buy a cheap digital scale like you have pictured, and rather than try and interface with whatever weird IC may be in it, just use the load cell directly. Most load cells are just resistors that change resistance under load, so I can't imagine it would be too hard to take something like an arduino and just measure the resistance of the cell.

 

[Linux-SWAT]

I can't do that for my project. But I kept this last resort option.
I googled around for one hour without success.
I was certain to find this on conrad or mouser, but no.

 

[WizardStan]

If you've got one, open it up and start googling for part numbers.

 

[T.T.]

what is your project anyway?

 

[levi]

How do you mean 'electronically read from'? You mean some sort of serial port you can hook up to? That sounds rather specialist, so it's something you'd need to build yourself from components.

Only problem is when I search my usual component supplier for a 'strain gauge' it actually returns me a couple of pages of piezoelectic pressure sensors. I guess if you were to put a filled airtight bag inside which gets squeezed as the hook gets pulled, you could make that work, but it still seems a lot of work against just a flexible strip you can measure the resistance of, which is what I understand a strain gauge usually consists of.

 

[Hellfleck]

not seen these with a serial output and the small ones are battery driven with auto power off

I would suggest you get one you like, take it apart and see how the measurement cell is driven (take a few data point weight vs. voltage), then cut out their electronics and hook up your own micro to the cell to measure it ... will take a bit of tweaking and calibrating but most of these cells are somewhat linear or can be approximated

 

[Binky]

If you don't mind a bit of soldering, this might be a good place to start:

https://learn.sparkfun.com/tutorials/load-cell-amplifier-hx711-breakout-hookup-guide

 

[FBnil]

I found a lot on aliexpress (arduino compatible), search for "digital weight sensor" add "pull" if it needs to pull down (more expensive), even hydraulic pressure sensor.

example (cheapest)

A push sensor can be made a pull down sensor with a bandana and a hook...

 

[Hellfleck]

https://learn.sparkfun.com/tutorials/load-cell-amplifier-hx711-breakout-hookup-guide

very nice link from there to another board : https://learn.sparkfun.com/tutorials/openscale-applications-and-hookup-guide

which is basically a board for 4 point weight scale with serial output ... nice, need to get one : https://www.sparkfun.com/products/13261?_ga=2.250169990.1461501715.1510836674-579741278.1510836674

 

[Linux-SWAT]

Nice suggestions everybody ! I was clearly missing some vocabulary terms.
Thanks !

 

[comradekingu]

You could OCR the display with a webcam?

 

[Linux-SWAT]

No .
It's a load cell using tension that I need.
Europe and US made are very expensive, but cheap versions are available in China.

 

[benoitb]

You could OCR the display with a webcam?

I was thinking that or even looking at the display interface itself and finding how to decode it. Since it's the cheap device's only output it could be your input.

 

[Linux-SWAT]

Indeed, but I would like to use a more "industrial" process.

 

[Grench]

Hmm... How about a bluetooth fish scale?
http://www.tacklewarehouse.com/Conn...vBS0W2P9aLp2cbNXqPh50PQOqYBv2f4EaAmgkEALw_wcB

When I first saw that I thought it was pointless... Maybe you found the point to it?

 

[Linux-SWAT]

Too much latency.

 

[kuru]

A push sensor can be made a pull down sensor with a bandana and a hook...

Spoiler

Am I helping?

 

[FBnil]

Am I helping?

I genuinely LOLed. You should have added subtitles: "Come with me if you want to live"