| Author |
Message |
flipper
Guest
|
 Posted:
Sat Oct 08, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
|
|
On Fri, 7 Oct 2005 23:14:11 +0200, "Ruud Broens" <broensr@wanadoo.nl>
wrote:
| Quote: |
"flipper" <flipper@fish.net> wrote in message
news:upack1ttm3oncpau05mulagdtn86bla7pb@4ax.com...
: On Fri, 7 Oct 2005 17:29:31 +1000, "Phil Allison"
: <philallison@tpg.com.au> wrote:
:
:
: >"flipper"
:
: >>>>The tolerance number assumes nothing;
: >>>> they'll simply be within 1% ...
:
: >>> ** WRONG.
:
: >> You need to learn a new word.
:
:
: > ** You need to go get fucked - psycho.
:
:
: >>>New Metal Film resistors are and need to be well within the 1% error
: >>>maximum
: >>>to allow for aging.
:
: >> Sorry, but no.
:
:
: > ** Prove it.
:
: > With real data.
:
:
: I did, below.
:
: >>>** That is NOT my experience over 40 years of dealing with the critters.
:
: >> I don't know what you think your experience has been but the
: >> specification for tolerance is initial at 25C and the rest are
: >> add-ons. Always have been.
:
:
: > ** Crap.
:
: >> For example
:
: >> http://www.universalimport.se/Mfr.pdf
:
:
: > ** Meaningless.
:
:
:
: >.......... Phil
Who'd have thought a 1 W resistor could lead to such heated argument :-)
Where to get is off the screen.
Just measured some 156 56K 1% BC (Philips) metalfilm resistor values.
Result: Avg 55,86 K Max: 56,26 K Min 55,69 K
average is 0,25 % off, 95% are within 0.6 %, all are within -0.6..+0.45 %
Since they are on a (much longer) roll, it's interesting to see the values
in sequence. It suggests a production process with upper and lower
trigger levels changing some production parameter , ie. values are
continuously measured and fed back into the manufacturing process,
hence some 'extreme' value on the roll will give a 'swing of values' into the
other direction and vice versa, some kind of noisy oscillation around the
mean value. From this, it doesn't seem likely such a low cost product as
a resistor is scrutinized for possible 0.1 % values, a separate more controllable
production process for those makes more sense.
It's just one batch, but measurements seem to bear out Phil's statements,
in this case
|
As I mentioned to Phil, my example was not to say those particular
type of resistors were made that way but to show how a manufacturing
process might not result in the 'assumed' distribution.
Phil and Ian might be interested to hear if your results produced a
bell curve, though.
Doesn't matter much to me because I don't design circuits 'hoping'
some percentage of them will happen to come out 'better' than spec'd.
|
|
| Back to top |
|
 |
flipper
Guest
|
| Posted:
Sat Oct 08, 2005 4:43 am Post subject:
Re: Where to get 1watt 1% resistors. |
|
|
On Fri, 07 Oct 2005 17:43:33 GMT, "Ian Iveson"
<IanIveson.home@blueyonder.co.uk> wrote:
| Quote: |
"flipper" <flipper@fish.net> wrote in message
news:5d8ck192a0c2grsgoacr35qp7fseht9kfg@4ax.com...
On Fri, 07 Oct 2005 06:16:04 GMT, "Ian Iveson"
snip of pedantic arguing
Doesn't matter because the issue is what the tolerance
specification
means, not what you're going to 'guess' from how you think they're
made, sorted, culled, or not, or whatever.
You don't get to decide what the issue is.
|
I do when it's about what I posted and what I said. And the point was
one thing, what a 1% tolerance specification meant and what the
resultant tolerance is with two 1% resistors in series.
It means you can count on the individual resistors being within 1% of
the nominal value and two in series will be within 1% of the nominal
series value.
If you want to play games with 'distributions' then so be it but I'm
not playing. |
|
| Back to top |
|
|
Phil Allison
Guest
|
| Posted:
Sat Oct 08, 2005 10:08 am Post subject:
Re: Where to get 1watt 1% resistors. |
|
|
"Ruud Broens"
| Quote: |
http://www.universalimport.se/Mfr.pdf
** Meaningless.
.......... Phil
Who'd have thought a 1 W resistor could lead to such heated argument :-)
Where to get is off the screen.
Just measured some 156 56K 1% BC (Philips) metalfilm resistor values.
Result: Avg 55,86 K Max: 56,26 K Min 55,69 K average is 0,25 % off,
95% are within 0.6 %, all are within -0.6..+0.45 %
Since they are on a (much longer) roll, it's interesting to see the values
in sequence. It suggests a production process with upper and lower
trigger levels changing some production parameter , ie. values are
continuously measured and fed back into the manufacturing process,
hence some 'extreme' value on the roll will give a 'swing of values' into
the
other direction and vice versa, some kind of noisy oscillation around the
mean value. From this, it doesn't seem likely such a low cost product as
a resistor is scrutinized for possible 0.1 % values, a separate more
controllable
production process for those makes more sense.
It's just one batch, but measurements seem to bear out Phil's statements,
in this case
|
** Now that is " real data " and confirms my experience exactly.
The main production variable is imperfect consistency in the metal coating
applied to the ceramic tubes - it they were all perfectly identical, the
lathe that cuts the spiral in the surface would not need to measure each one
as it worked.
Thanks for those figures - Rudy.
.......... Phil |
|
| Back to top |
|
|
Jeff Thompson
Guest
|
| Posted:
Sun Oct 09, 2005 9:58 pm Post subject:
Re: Where to get 1watt 1% resistors. |
|
|
Dope mcSmoke wrote:
| Quote: | Phil Allison wrote:
"Dope mcSmoke"
Phil Allison wrote:
** Use two 0.5, 0.6 or 0.75 watt 1% MF types in series.
That'd be like a 1W 2% resistor
** WRONG !!!
Even if *both* resistors were 1% high, the series value is also 1% high.
Using resistors in series or parallel IMPROVES the % accuracy of the
final value.
........ Phil
Thinking about it now I realize that:
two 1% 100R in series being 1% off could make 2*99R=198R or 2*101R=202R
which is still 1% off, so you're right. But you still don't have to be a
total bitch about it.
Yes he does, He's incapable of anything else. |
|
|
| Back to top |
|
|
|
|
|
|
Profile
Log in to check your private messages
Log in