KOA Speer 1/4 watt resistors - why are they so tiny?

[jefe]

I just received a Mouser order with a bunch of KOA Speer 1/4 watt resistors. I opened the package, and was surprised to see these tiny little resistors - much smaller physically than what I'm used to seeing. They look like 1/8 watt-sized resistors. I double checked, and yes, the individual part packaging (and my packing slip) list them all as 1/4 watt, not 1/8 watt.

As an example, here's the Mouser link to one of the resistors I ordered:
Mouser P/N 660-CFS1/4CT52R183J

Another (maybe) weird thing: When I was ordering, I noticed that the description said "1/4Watt Metal Film Resistors 18K OHM 5% 1/4W". At the time, I thought it was a little strange to see "Metal Film" and "5%" in the same description. I'm used to Metal Film being 1% tolerance, and Carbon Film being 5%. I was only looking for 5%, so I went ahead and ordered and didn't think too much about it.

I did take a quick look at the datasheet before I ordered, but I didn't think to actually check the physical dimensions.

Whatever, I'm sure they'll work fine. I was just wondering if anyone else had this experience, or had any opinions on these tiny things. They're so small that they could be described as "cute". They make me mad, like when I see a tiny cute little stuffed animal - j/k.

Oh, and BTW, I HATE ordering from Mouser. Stuff like this always happens to me when I order from them. But, they do stock just about everything, so I'll probably order from them again.

[drewl]

Better technology
That's why my vision is going downhill.......staring at teeny tiny pc boards with teeny tiny components!

[caress]

with mouser it's always a good idea to check the datasheet for the item, the page in the product list and the item page, as to avoid getting something weird.  i personally love mouser and order from them all the time, but i have probably spent at least $20-30 on smd, knobs with the wrong shaft size, pots with long shafts, etc...  it hasn't happened in a while for me at least - practice makes perfect!
mouser has loads of other 18k 1% metal film resistors, too.

[R.G.]

I see that Mouser gave you the link to the datasheet which correctly and exactly describes the size of the resistors for the part number you ordered. And:

I did take a quick look at the datasheet before I ordered,

So you were warned, right?

but I didn't think to actually check the physical dimensions... BTW, I HATE ordering from Mouser. Stuff like this always happens to me when I order from them.

You know, every time I've ordered from Mouser, I got >exactly< what I ordered. It was not always what I wanted, but it was exactly what I >ordered<.

If they give you exactly what you ask for, are you blaming them for offering you too many choices? 

Seriously, think about it. You want a place to send you what THEY think you want, or to reliably send you what you tell them you want out of a huge selection?

I guess I'm getting around to - go take a long look in the mirror. I do that myself a lot. It helps me assign blame for my mistakes properly. 

[jefe]

If they give you exactly what you ask for, are you blaming them for offering you too many choices? 

Yeah, I am! j/k... but ordering capacitors from them can be a daunting task - there are thousands of choices! But you're right, I got exactly what I ordered. On the up side, I don't really see it as a problem - I ordered 1/4 watt resistors, I got 1/4 watt resistors.

I wasn't really posting this to bitch about Mouser - sorry if it came off that way. I was just wondering what the deal was with these small resistors. Is it better technology, as drewl suggested? (And yeah, those color bands were hurting my eyes, lol!)

Again, it's no big deal.

Has anyone else used these resistors?

On a side note, we recently had an issue here at work where a supplier installed the wrong resistors on our boards. One of our inspectors picked it up because the resistors just looked physically too small - smaller than he was used to seeing. By tracing back through the paperwork, we were able to confirm that the supplier had indeed installed 1/8 watt resistors, where they were required to install 1/4 watt. My point is simply that I - and other people I know - are used to 1/4 watt resistors looking "a certain way" (being a certain size), and when something doesn't look right, it can... I dunno, get your attention?

[R.G.]

I probably should have put more smileys in. 

It really is better technology. I've run into this before. The nominal power rating of a resistor, just like the power rating of a transformer is a thermal thing. That is, it is properly rated at the temperature where it will just barely not melt down into a puddle or go up in smoke. The filament of a 100W light bulb is actually very tiny compared to a 100W resistor. The difference is that the 100W resistor has to keep its surface temperature below the charring point of PCB material. The light bulb filament does not.

The improvement in technology is that they have new resistive materials in the smaller resistors that can run hotter and not fail. That lets them put the same watts in a smaller - and hotter - package.

Since most resistor in effects dissipate under 10mW, not the 250mW rating of a 1/4W resistor, they will work fine.

The only place you may really need 250mW dissipation in a normal-ish pedal is in the limiting resistor of an LED.

[jefe]

I probably should have put more smileys in. 

No problem, you used the perfect amount of smilies in your earlier post. 

It really is better technology. I've run into this before. The nominal power rating of a resistor, just like the power rating of a transformer is a thermal thing. That is, it is properly rated at the temperature where it will just barely not melt down into a puddle or go up in smoke. The filament of a 100W light bulb is actually very tiny compared to a 100W resistor. The difference is that the 100W resistor has to keep its surface temperature below the charring point of PCB material. The light bulb filament does not.

The improvement in technology is that they have new resistive materials in the smaller resistors that can run hotter and not fail. That lets them put the same watts in a smaller - and hotter - package.

Since most resistor in effects dissipate under 10mW, not the 250mW rating of a 1/4W resistor, they will work fine.

The only place you may really need 250mW dissipation in a normal-ish pedal is in the limiting resistor of an LED.

Thanks a million for the explanation R.G. - it was kinda bothering me, or more acurately, I was very curious about the small size of these resisitors. If the reason is "better technology", I can certainly live with that.   

[Pushtone]

I had the same experience.
Got the KOA tiny resistors and was pleasantly surprised.
About the size of a diode.

I check and double the dimensions for caps but for resistors I pick 1/4W and be done with it.

I seem to have to order from a mix of resistor manufacturers at Mouser.
One brand won't have all the values or Mouse has a high min qty.

[skiraly017]

Mouser has always been very cool about me returning my "mistakes". However, there was one time when I had thoroughly researched a part to the smallest detail to make sure I got it right. When it arrived it wasn't what I had ordered. Turned out the part numbers were skewed somewhere in their system.

[jefe]

Mouser has always been very cool about me returning my "mistakes". However, there was one time when I had thoroughly researched a part to the smallest detail to make sure I got it right. When it arrived it wasn't what I had ordered. Turned out the part numbers were skewed somewhere in their system.

That's cool, I'm glad you've had good experience with them for the most part, as have I.

I just want to point out that in this particular case, I didn't make any mistakes in ordering (and I do make my fair share of mistakes from time to time) - like I said, I ordered 1/4 watt resistors, and I got 1/4 watt resistors. The only surprise to me was the newer, smaller size - like Pushtone said, they're about the size of a diode.

Tonight, I'm building the Axis Face Silicone from Fuzz Central.   

[Solidhex]

Better to be small than too big! I have a ton of components from all over that are too big for most practical pedal use.

--Brad

[Paul Perry (Frostwave)]

I expect that a physically small 1/4 resistor dissipating a full 1/4 watt, will run hotter than a larger 1/4 watt resistor running with the same power.
Unless the first one has very conductive leads, and that is where most of the heat goes.
But as RG says, most stompbox resistors don't burn much power at all, if they did we couldn't afford the batteries

If you ever ARE running a resistor at the limit, stand it up free of the board & don't put it next to an electro.