creedmore sports new scale

R

rsmithsr

Well-known member
they have introduced a new scale.
low cost and direct "grain" readout.
some are concerned that other scales my lose "accuracy" in math conversions.
the possible down side is the scale is straight load cell technology, not magnetic dampened.
looks like it would be ok for a low volume loader at home.
NOW we need someone to buy one and report ??
 
rsmithsr said:
they have introduced a new scale.
low cost and direct "grain" readout.
some are concerned that other scales my lose "accuracy" in math conversions.
the possible down side is the scale is straight load cell technology, not magnetic dampened.
looks like it would be ok for a low volume loader at home.
NOW we need someone to buy one and report ??
Click to expand...

I can assure the skeptical that they are not losing any "accuracy" in math conversions. Load cells, etc read out in volts, not any measure of mass/weight, which are digitized using an Analog to Digital converter. From there the conversion from bits to any unit of your choice is identical. It would be a very naively made system that performed a conversion from bits-to-something and then converted from *that* to something else. Furthermore any of these devices are likely to run off of a 32-bit processor, but even if they're only 16-bit they have more mathematical precision than you will ever be able to make use of in real life.

GsT
 
gene i do not buy it either.
i know guys that use the fx120i in grams,
because it is more "precise" more digits in the readout.
i do not even try to talk to them
my OPINION is that creedmoor has taken the trend,
and marketed to it.
 
"More accurate" and "less accurate" math....... I'm w/Smith, I can't even carry on a casual conversation with these people.

It's like playing chess with a pigeon

Or "arguing" with someone who thinks solar energy or electric cars are saving the planet

Now the mechanics of the scale??? I know nothing about. But I do have 11 scales, and like my calipers and mics and chronographs I can just check them one against the other.

I wonder does CS take bitcoin.....hmmmm....
 
A/D converters have a couple of different properties that can contribute to errors.
Resolution is the first one.
How many bits does the converter use to determine a value.
A 10 bit converter has 1,024 possible values.
Each additional bit doubles the number of possible values.
12 bits produces 4,096 values.
14 is 16,384.

The 'value' of each bit is a function of the range (in whatever unit you care to use).
The range is set by whatever gain the output of the D/A and its amplifiers are set up
to produce.Many A/D converters have a nominal 1 volt input range.
Over that 1 volt range there are gain errors, linearity, and
offset errors.
In many cases there is also some 'digital curve fitting' coming into play.

This is the reason for multiple points in the setup.
Commonly simple curve fitting will use zero, and a single weight near maximum.

More sophisticated curve fitting might use 0, 1/4 of the range, 1/2 of the range, and then a fill scale setting.
Easily accomplished with a set of weights that are equal.

Generally the more points there are the better.
One simple trick is to use a larger number of equal weights.
This allows the simple use of the same value of weights.

There are high resolution 'successive approximation' converter.
They can get into 20 bits and higher.
 
Last edited:
brickeyee said:
A/D converters have a couple of different properties that can contribute to errors.
Resolution is the first one.
How many bits does the converter use to determine a value.
A 10 bit converter has 1,024 possible values.
Each additional bit doubles the number of possible values.
12 bits produces 4,096 values.
14 is 16,384.

The 'value' of each bit is a function of the range (in whatever unit you carer to use).
The range is set by whatever gain the output of the D/A and its amplifiers are set up
to produce.Many A/D converters have a nominal 1 volt input range.
Over that 1 volt range there are gain errors, linearity, and
offset errors.
In many cases there is also some 'digital curve fitting' coming into play.

This is the reason for multiple points in the setup.
Commonly simple curve fitting will use zero, and a single weight near maximum.

More sophisticated curve fitting might use 0, 1/4 of the range, 1/2 of the range, and then a fill scale setting.
Easily accomplished with a set of weights that are equal.

Generally the more points there are the better.
One simple trick is to use a larger number of equal weights.
This allows the simple use of the same value of weights.

There are high resolution 'successive approximation' converter.
They can get into 20 bits and higher.
Click to expand...

Kinda like my beam scale with the ceiling fan on.
 
rsmithsr said:
gene i do not buy it either.
i know guys that use the fx120i in grams,
because it is more "precise" more digits in the readout.
Click to expand...

Well, they should get their scale calibrated in tons. It will have lots of digits and be very precise.
 
I remember having to explain to another PhD EE that
"not all the digits on a frequency counter" mean something.

He really had no idea of how the accuracy of the gate counter in the unit was only about 1E-6.
He accused me of wasting money on an extremely accurate reference oscillator to lock the counter to.

We ended up renting an atomic clock to get enough digits to be useful in testing our EW system.

And even that unit had to be in a temperature controlled screen room to get what we needed.
Output accuracy still depended on the unit being at 65 F, +/- 1 F.

That allowed us to have an accuracy of around 1e-16.
 
Last edited:
You must log in or register to reply here.
Back
Top