Re: bathroom scale hysteresis

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Hi,
Thanks to all who took time to reply.

Yesterday I went to a Bed, Bath, & Beyond store where there were
several models on display.

I brought with me several 0.5 liter water bottles (approx 1 lb.) and
half-consumed one (approx 0.5 lb.) so that I could adjust my weight in
0.5 lb. increments. I tried 3 models and found two that I think
exhibited this programmed hysteresis, and one that did not.

The $40 Thinner TH300 uses load cells and reports to 0.5 lb.
Holding an empty shopping basket and full pockets, I measured at 181.0
six times in a row. Then, holding ~0.5# in my basket, I still measured
181.0. Again, holding ~1#, I still measured 181.0. Then, when holding
~1.5#, apparently past the programmed hysteresis threshold, scale
reported 182.5.

The $50 Tanita BF679 reports to 0.2 lb. It did not have hysteresis.
Each measurement was independent, reporting like 178.2, 178.4, 178.6,
178.4, ... (I wasn't holding an empty shopping basket for this one).

The $60 WeightWatcher WW60 (Scales by Conair) uses load cells and
reports to 0.1 lb.
I (plus basket) measured 180.7 six times in a row. Then holding ~0.5
lb., I measured 180.7 again. Then, holding ~1#, I measured 181.9 .

So, I see this programmed hysteresis in some models, with a breakaway
delta of ~1#.

I had thought I originally noticed this two months ago in several
Taylor models and a Tanita, but I wasn't able to test any Taylors
yesterday and my one Tanita test didn't show it.

Best regards,
John Ruckstuhl

Outstanding report...thanks!

My experience with Tanita has been the same - no hysteresis noted.

Consumer Reports magazine tested several models of body fat scales in the
last year or so. As I recall, they liked the Tanita the best - they warned
that body fat was quite variable, and probably not very accurate, but that
the body weight reported by Tanita was better than most other units (not
sure if they tested for hysteresis).

GG

[email hidden] wrote:
[snip]

Quoted message said:

The $40 Thinner TH300 uses load cells and reports to 0.5 lb.
Holding an empty shopping basket and full pockets, I measured at 181.0
six times in a row. Then, holding ~0.5# in my basket, I still measured
181.0. Again, holding ~1#, I still measured 181.0. Then, when holding
~1.5#, apparently past the programmed hysteresis threshold, scale
reported 182.5.

[snip]

Quoted message said:

John Ruckstuhl

Do you think that this behaviour would result if the ADC resolution is
coarser than the display resolution, for example the LSB represents 1.5#?
Or maybe the ADC has missing codes. This wouldn't require tricky
programming, just a bad ADC.

In article <[email hidden]>,

Quoted message said:

So, I see this programmed hysteresis in some models, with a breakaway
delta of ~1#.

I had thought I originally noticed this two months ago in several
Taylor models and a Tanita, but I wasn't able to test any Taylors
yesterday and my one Tanita test didn't show it.

I have a Taylor bathroom scale, with a 1# hysteresis. I weigh myself
every morning. Each new weight is either the exact same as the
previous weight or at least 1.2 lbs different. (The scale shows
weight to 0.2 pounds.)

Seth
--
Oh well, never mind. I have the electrodes and the conductive gel and
a serviceable familiarity with sendmail.cf -- Tanuki the Raccoon-dog