resistor brands

[peterthenovice]

what are some well know resistor brands. some that have good data sheet,etc. first class and second class resistors. I'm thinking of doing a science project( i'm fourteen) on the temperature variance of resistors.

[c4757p]

I'd just go to Mouser or Digi-Key, search for a common value, and start browsing. There are a ton. A couple that pop into my mind are Vishay/Dale and KOA Speer. Maybe try eBay for some Wun Hung Lo resistors as well - trust me, they are crappy. Might be good for such an experiment. Also consider actually testing these (scrape off the paint) to see if they're really the type they claim they are. I've heard of carbon films being painted blue and sold as metal film.

More important than brands, IMHO:

- Different types: Metal film, carbon film, metal oxide. Perhaps compare with older tech by getting some carbon composition (they still make them).
- Different values: Both tiny (1-10 Ohm, unless you can measure four-wire), medium (1k or so) and large (10Meg?).
- Different forms: Axial and surface mount (you can solder leads onto the surface mount resistors with a steady hand). Maybe different sizes of those.
- Test a bunch of identical resistors to account for variation in the same line.

And of course get multiple brands of each. Resistors are cheap, no reason not to get every variation you can think of.

[Dr. Frank]

what are some well know resistor brands. some that have good data sheet,etc. first class and second class resistors. I'm thinking of doing a science project( i'm fourteen) on the temperature variance of resistors.

Hello Peter,
for your project (i.e. about the 'Temperature Coefficient'), you don't have to select by manufacturer, but by technology.
Different manufacturers offer the same technologies.
The difference between manufacturers might be, how well they produce the components, i.e. that's about quality and reliability (not relevant for you), and sometimes, if they really fulfill their published specifications.

For your purpose, you'll need resistors of the main different technologies: Thick Film, Thin Film (= Metal Film), Carbon (hard to find), Wirewound Power, Wirewound Precision (expensive), Metal Foil (very expensive).
 
Provided you have a sophisticated DMM / Ohmmeter (4 terminal / Kelvin connection and maybe offest compensation), you may determine the T.C. of all of them (difficult for the high grade resistors).

Regarding manufacturers, VISHAY has acquired most of the high quality resistor brands as Beyschlag, Draloric, Dale, Roederstein, Sprague, etc.
Vishay also have their own manufacturing, and invented the metal foil technology.

Other independant and good suppliers are KOA, ROHM, Yageo, Panasonic.

Depending on your test setup, you'll need perhaps through-hole components instead of SMD.

Perhaps, you also want to include resistor technolgies for temperature measurements, i.e. with much higher T.C. and/or  non-linear R(T) characteristics, then add NTC, PTC, Pt100.

(You'll need a thermometer, anyhow)

Frank
 

[Fsck]

If you want some amusement, get ebay unbranded chinese resistors. Their precision and accuracy are both amusing when compared to commonplace branded ones like Vishay and Dale.

[free_electron]

Isabellenhutte resistors. Those are top notch !
I got some really whacky brands that do 0.3ppm/c ... As tempco.

Caddock
Roederstein
Yageo
Stackpole
Taiyo yuden

[ftransform]

My metal thin film resistors from amazon were approximately 50ppm/dec C when measured (advertised as 100ppm). My ebay carbon film resistors from china were approximately 250ppm/c when measured. Not too shabby. I don't think the tempco was advertised.

A yaego precision resistor kit (e96 values in the 10k range, marked 100ppm) had a tempco of 7 ppm on a random resistor. Much better, but not always necessary

The one thing you really need to watch out for is ebay ten turn trimpots. The single turn panasonic trimpots are ok (250ppm) but the 20 turn bochen's are a joke.

In order to be a reasonable engineer you should probably have an assortment of cheap and high quality parts.

I don't think there is a good need to use a 20ppm/c resistor to current limit a indicator LED or as a pullup/pulldown for digital logic, the most heinous of values are used for this purpose (see dave jones video on carbon paste resistors!, I think he said they were like +-50% ). I keep a book of china ebay metal film resistors (as many values as you can get), a book of carbon film resistors and precison books that have 5 each of e96 values per decade (still working on this expensive collection).

If you find my previous thread on trimpot temperature co changes I detail a crude but effective test setup for measuring temp-co with common items, you would probably want to make it a bit more refined if its for a science fair though. You will need a decent ohm-meter for this experiment.

[peterthenovice]

thanks for the information. I plan on using 3-5 brands 2-3 tech metal-film carbon, etc. tested over 150-200 degrees C with my hakko temp adjust iron

[kfitch42]

thanks for the information. I plan on using 3-5 brands 2-3 tech metal-film carbon, etc. tested over 150-200 degrees C with my hakko temp adjust iron

You probably don't want to get these guys tooo hot. From one random spec sheet I found:
http://www.vishay.com/docs/20035/dcrcwe3.pdf
it has a temp range of -55 to +155 C. Getting to -55 might be a stretch. You are probably only going to be able to get about a 100 degree C swing.
at 100ppm/C you _should_ see at MOST (100*100)/1000000 = 1% change in resistance. i.e. 1 ohm on a 100ohm resistor.  Make sure you multi-meter can really show that reliably.

[c4757p]

thanks for the information. I plan on using 3-5 brands 2-3 tech metal-film carbon, etc. tested over 150-200 degrees C with my hakko temp adjust iron

The temperature is too high - you're not going to see much by testing them outside their rated range. You may end up damaging them, even. Also, the temperature won't be very stable like that. My suggestion is to use a big power resistor as a heating element - just strap the resistor to it, run current through the power resistor, and let the temperature stabilize. With a variable power supply and a chunky ceramic wirewound, you can get just about any temperature you want.

[kxenos]

And for colder measurement you could probably use something like a bowl with oil that you leave in the fridge overnight with the resistors inside (the contacts being outside the bowl) and measure them while it slowly heats up to room temperature noting the liquid's temp. and the resistance.

[peterthenovice]

And for colder measurement you could probably use something like a bowl with oil that you leave in the fridge overnight with the resistors inside (the contacts being outside the bowl) and measure them while it slowly heats up to room temperature noting the liquid's temp. and the resistance.

i had a heat source now i have a source a cool temps

[FenderBender]

Dale (now part of Vishay)
Caddock
Ohmite
Xicon

They're all pretty good.

[amspire]

thanks for the information. I plan on using 3-5 brands 2-3 tech metal-film carbon, etc. tested over 150-200 degrees C with my hakko temp adjust iron

You will do a much better job with a domestic oven and refrigerator and something to measure temperature, like a thermocouple probe that now comes with many multimeters. You want the resistor heated uniformly to get reliable results. A soldering iron on the leads will cause big temperature gradients in the resistor, and while I am sure you will see resistance changes, it will be hard to turn that into any meaningful ppm/C numbers.

[peterthenovice]

thanks for the information. I plan on using 3-5 brands 2-3 tech metal-film carbon, etc. tested over 150-200 degrees C with my hakko temp adjust iron

You will do a much better job with a domestic oven and refrigerator and something to measure temperature, like a thermocouple probe that now comes with many multimeters. You want the resistor heated uniformly to get reliable results. A soldering iron on the leads will cause big temperature gradients in the resistor, and while I am sure you will see resistance changes, it will be hard to turn that into any meaningful ppm/C numbers.

i plan on using a thermocouple.  this is a good idea.

[codeboy2k]

The one thing you really need to watch out for is ebay ten turn trimpots. The single turn panasonic trimpots are ok (250ppm) but the 20 turn bochen's are a joke.

if I needed something both low tempco and trimmable, what I usually do is put a high value trim pot across a lower value , low tempco resistor. This way the tempco of the lower resistor dominates. I think everyone knows this already ??

So for example, if I had a precision, low-tempco divider, say 10k top and bottom, 5ppm, and I wanted to trim the divider, I would use a perhaps a 100 ohm, 5ppm resistor in the middle of the two 10k's that make up the divider, and trim that 100 ohm with a parallel 5k trim pot, 250ppm. This way the tempco of the 5k trimpot, what ever it is, does not have as much effect on the final value.  The 100 ohm's tempco dominates.  I've drawn it up, because drawing a circuit, however simple, is always better than describing it.

[cwalex]

if I needed something both low tempco and trimmable, what I usually do is put a high value trim pot across a lower value , low tempco resistor. This way the tempco of the lower resistor dominates. I think everyone knows this already ??

Thanks for this tip. I didn't know this already

[ptricks]

As others said mouser, digikey all their stuff is going to be good.
Stay far away from vendors on ebay selling resistors really cheap.
Those resistors are okay for general use but the lead wire they use is tiny and breaks easily.

[Prizmatic]

God bless cheap Chinese metfilm resistors, great for hobby RF use. Not had a painted one or broken lead yet, and my parts bins are full.