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Hey, I was scraping the blue coating off some through hole MF's Do they laser trim those too, or something else? I couldn't see much, but when I was done, 10k had become 10.5k. (I could do in circuit, tweaking with an exacto knife.)
George H.
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Interesting, Don't CC's have a terrible tempco. (We used them as low temp sensors, maybe better near RT.)
Spiral grinding of cheap leaded resistors:
If I was them, I wouldn't be talking about the mercury contacts.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
I recall one of the local disties back years ago decided to stop carrying resistors-- their bean counters figured it was something like
80% of their costs for 20% of their volume, and they wanted to concentrate on high-markup semiconductors. No longer around, natch.Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
ure
Neat, Thanks. (I take it those are spitting out 1% metal film resistors.)
Hmm, how else are you going to make contact to the spinning lead?
(there's some indium gallium... ? tin? alloy that melts below 100C.)
Got it, Field's metal. (I assume named after our own John Fields :^)
George H.
"The Journey is the reward"
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n moops.. nope it is indium gallium and tin... Galinstan.
Geo
"The Journey is the reward"//
speff.com-Hide quoted text -
The more modern Ohmite carbon comps were about 5 times better that the really old ones that had the leads spiral wrapped around the ends.. The 47 to 100 ohm Ohmites were very nice as fuses / overload indicators when placed in the cathode of series power regulator tubes. Discoloration "level" would indicate a certain amount of overload, and next cracking to open, and then carbonizaton and finally "busted black".
That's like the distributors who tried a $50 minimum order for repair parts. They claimed they couldn't afford to keep filling $20 minimum orders. It didn't last very long before they either went back to $20, dropped any minimum or closed their doors.
How accurate was your meter?
"George Herold"
In the first video Dave finds that some Philips resistors have a ~
+/-0.5% distribution right around the ?correct? value.In the second he finds that some cheaper (Xicon?) also have a 0.5% ?spread?, but the average is a bit (~0.35%) lower than nominal.
This raises a bunch of interesting questions. Do any resistor makers publish this sort of data?
** The tolerance percentage includes a nominal service life - so a nominal 1% tolerance part is usually much tighter when new. That is all that is being claimed.Does buying resistors from a ?better? manufacturer lead to resistors with a better mean.
** Pointless even reseching it as it would be a moving target.So does anyone know how 1% resistors are made? I find it hard to believe that they trim each one.
** That spiral cut does not get there by itself and the cutting machine stops when the value is right.Tighter tolerances ( than say 1%) requires slower operation and or the use of a laser - so the parts cost more.
.... Phil
carbon film also has a spiral cut.
how about carbon, or copper, brushes: two each end so you can make a kelvin measurement.
Whatever you use cutting is going to cause localised heating so you'll have thermocouple effects messing with your measurements, for small resistors you'll probably have to use AC to counter that.
-- ?? 100% natural --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
George Herold a écrit :
Lots of ways. For ex, after a first meas, which you probably even can infer from the previous bulk value(s) in the batch you go near the final cut position, then make contacts with a wire/flex/whatever that have to withstand limited rotation. Or maybe cover the full angle span with a spiraled conductor, or brush contacts, or... or...
-- Thanks, Fred.
Spehro Pefhany a écrit :
And that one is supposed to help the customer build confidence...
Or that one that is just like the machines are in the living room...
A friend of mine that once was in charge at Vishay for solving some quality issues on a production line for high value resistors (in India IIRC) told some horror stories that just reminds me some of those pics...
-- Thanks, Fred.
Not always.
Matching and culling mass production runs of resistor bodies is easy.
They can do (read it) it before coating, terminating and marking, or they can make it whole, and read it and mark it afterward.
I am sure that for testing lot run values, they use a platinum faced wiper.
Nah! He melts at a much higher temperature ;-)
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
He won it in a spelling bee.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
"SoothSayer"
** What an idiotic remark..... Phil
Yours? Yes, it was... your retarded crack was absolutely an idiotic remark to make.
You grasp of manufacturing processes rests firmly at nil.
s
ugh
aThat's cool, Thanks! Looks like about one resistor every second or two. So maybe 3x10^7 per year. (I'm still amazed they can make a profit selling them.)
I wonder how many resistors the average American 'consumes' in a year.
George H.
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