All of which is fixed by a voltage regulator
Comment on Scales that refuse to measure if the battery isn't brand new
Thorry84@feddit.nl 2 months ago
That’s because of the way these scales work. They use a material that deforms under stress and when it deforms the resistance changes. By putting current through this material and measuring the voltage drop, it can be mapped to how much stress the material is under and thus how much weight is on the scale.
This is a pretty roundabout way and has a lot of caveats, but it is very cheap. So cheap scales always work this way. That’s why they aren’t super accurate and have deviations depending on things like temperature. Another big downside is any permanent deformation ruins the calibration, giving incorrect results. That’s why you never put more weight on kitchen scales than it says, it will break them.
The issue you are running into is the way it measures. It applies a very specific voltage and current in order to get the result. The lookup table it uses is only valid within a narrow range. When the battery voltage goes outside that range, it can no longer perform the measurement. Even though there’s plenty of juice for things like the little processing chip and the LCD display. They don’t need a lot of power and can do with low voltages. But it can no longer weigh anything so it just errors out with a low battery warning.
SkybreakerEngineer@lemmy.world 2 months ago
magikmw@lemm.ee 2 months ago
Except the cheap part. But likely not by much.
chonglibloodsport@lemmy.world 2 months ago
You can order 3000 3.3V low drop out (LDO) voltage regulators on LCSC for $25.50. That’s less than a penny each.
Ghoelian@lemmy.dbzer0.com 2 months ago
Yeah, but it’s more than 0 pennies each.
B0rax@feddit.org 2 months ago
Doesn’t help when you need 3.3V and the batteries are now down to 2.5V they are not putting a boost converter in there.
itsmect@monero.town 2 months ago
Batteries have one advantage over over supplies: extremely low noise. Even an good LDO will bump up the noise floor, and a cheap lcsc part will do so too. Plus you’s want a reasonably low dropout and quiescent current, which also increases price. Maybe 10ct in volume is reasonable for such a part - and yes, that will absolutely eat the margin
Buffalox@lemmy.world 2 months ago
Absolutely, My kitchen scale remains accurate and can use the same battery for years.
XeroxCool@lemmy.world 2 months ago
Eventually, the battery drops lower than the device needs. So no, none of which is fixed by a voltage regulator.
iamdefinitelyoverthirteen@lemmy.world 2 months ago
No, not voltage, current.
B0rax@feddit.org 2 months ago
Which in this case means: you need a constant supply voltage
thisguy1092@lemmy.world 2 months ago
Mighty informative, thank you
Wizard_Pope@lemmy.world 2 months ago
Look up piezolectric materials if you wanna know more
marcos@lemmy.world 2 months ago
The GP is not describing a piezoelectric scale. And you won’t be able to find any piezoelectric scale that is anything similar to “cheap”.
Wizard_Pope@lemmy.world 2 months ago
Well which principle do the cheap ones operate on?