Author Topic: Resistor Question  (Read 5907 times)

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Offline CheeseNoOnions

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Resistor Question
« on: October 07, 2010, 07:48:26 pm »
Hey everyone,

I just discovered this whole community via The Amp Hour via @mightyohm via @CollinMel via a youtube search for how-to's.   Anywho, I'm really new to everything, but have managed to finish some small audio synth kits.  I've read suggestions of using 1% tolerance resistors instead of the 5% in audio applications, but I don't know why.  I do understand what the tolerance means in terms of resistance value, but I don't know what this would do to an oscillator or wave generator.  Anyone have any ideas?

Thanks
 

Offline Simon

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Re: Resistor Question
« Reply #1 on: October 07, 2010, 07:57:44 pm »
Well ideally you want 0% tolerance resistors in any application but as most of us know we all have to live in the real world. In what perspective were you told to use 1% resistors ? was it in any particular part of a circuit ? I'd try to use 1% resistors in any design and they are much cheaper than they used to be but of course plain old 5% aren't bad for general use, it's down to what your prepared to spend really
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Offline FreeThinker

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Re: Resistor Question
« Reply #2 on: October 07, 2010, 08:05:02 pm »
Well ideally you want 0% tolerance resistors in any application but as most of us know we all have to live in the real world. In what perspective were you told to use 1% resistors ? was it in any particular part of a circuit ? I'd try to use 1% resistors in any design and they are much cheaper than they used to be but of course plain old 5% aren't bad for general use, it's down to what your prepared to spend really
Could Always try popping into your Ebay shop eh Simon DRAL (ducks, runs away laughing)
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Offline Simon

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Re: Resistor Question
« Reply #3 on: October 07, 2010, 08:14:21 pm »
I can't compete on resistors I buy them by the hundred but don't bother listing them, I don't set out to stock every part possible and act as a main stream seller (well not any time soon), I just bulk buy any parts i need getting a price break and resell the surplus for what I hope is a reasonable price and enough for me to break even and get some back on what i spent in advance, basically I bet i make more than I'd get for investing my pennies in the bank.

In the UK RS charge £5 carriage (if they actually happen to stock the part  :D) and Farnell want a £20 minimum order
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Offline FreeThinker

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Re: Resistor Question
« Reply #4 on: October 07, 2010, 09:03:23 pm »
I can't compete on resistors I buy them by the hundred but don't bother listing them, I don't set out to stock every part possible and act as a main stream seller (well not any time soon), I just bulk buy any parts i need getting a price break and resell the surplus for what I hope is a reasonable price and enough for me to break even and get some back on what i spent in advance, basically I bet i make more than I'd get for investing my pennies in the bank.

In the UK RS charge £5 carriage (if they actually happen to stock the part  :D) and Farnell want a £20 minimum order
Local RS outlet is very poor,holds very little stock.They seem to have become a logistics company holding small stock totals in each outlet and shipping them around the counrty ovrnight to meet "next day"
deliverys.Was quoted an 8 week lead time for a 20mhz crystal only a couple of weeks ago!!! Got one from Malpins over the counter.
Ps Don't take me too seriously I love poking fun at people and it sometimes goes a little wrong, try to control myself but sometimes the urge is too strong!! ;D
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Offline allanw

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Re: Resistor Question
« Reply #5 on: October 07, 2010, 09:15:16 pm »
1% resistors are typically metal film, compared to the common carbon composition resistors that are 5%. They're only slightly more expensive.

People say to use them because they have lower noise and better temperature stability than the carbon comp resistors.

The lower noise is probably imperceptible though
 

Offline JohnS_AZ

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Re: Resistor Question
« Reply #6 on: October 07, 2010, 09:22:40 pm »
Also bear in mind that if you buy 5% resistors, NONE of them will be within 1% of the target value.

For example, if you buy a bunch of 5% 100 Ohm resistors, they will all measure between 95-99 Ohms, or 101-105 Ohms.
The ones that do fall within that target window are sold as 1% resistors.
« Last Edit: October 07, 2010, 09:48:21 pm by JohnS_AZ »
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Offline allanw

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Re: Resistor Question
« Reply #7 on: October 07, 2010, 09:24:15 pm »
I don't think that's true, because you'll rarely find 1% carbon comp resistors or 5% metal film resistors. They manufacture them with different materials.
 

Offline JohnS_AZ

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I'm either at my bench, here, or on PokerStars.
 

Offline JohnS_AZ

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Re: Resistor Question
« Reply #9 on: October 07, 2010, 09:41:00 pm »
I'm either at my bench, here, or on PokerStars.
 

Offline JohnS_AZ

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Re: Resistor Question
« Reply #10 on: October 07, 2010, 10:12:40 pm »
And if you want to TOTALLY geek-out on resistors ...  :) ...

Basics of Linear Fixed Resistors
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Offline allanw

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Re: Resistor Question
« Reply #11 on: October 08, 2010, 03:34:24 am »
But they're a lot rarer/more expensive. If you go to Digikey and look at their lowest priced 1kohm resistors, all the 1% ones are metal film and all the 5% ones are carbon comp.

For higher powers and such this isn't necesarily true, but it holds for 0.125W to 0.5W at least.
 

Offline CheeseNoOnions

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Re: Resistor Question
« Reply #12 on: October 08, 2010, 04:44:28 am »
Well ideally you want 0% tolerance resistors in any application but as most of us know we all have to live in the real world. In what perspective were you told to use 1% resistors ? was it in any particular part of a circuit ? I'd try to use 1% resistors in any design and they are much cheaper than they used to be but of course plain old 5% aren't bad for general use, it's down to what your prepared to spend really

From "Making Music with the 566"
By Thomas Henry

"Incidentally, both C and R should be good quality units (polystyrene or poly film for C, metal film for R) for best stability in music circuits."  I've also seen alot of kits where 1% are used throughout the design, but then there are others where they use the 5%.  You're right it's likely just a price thing.  I would spend the extra money, but does it really make a huge difference in the sound or is there some other consideration a novice wouldn't know about? 
 

Offline ziq8tsi

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Re: Resistor Question
« Reply #13 on: October 08, 2010, 04:50:43 am »
if you buy a bunch of 5% 100 Ohm resistors, they will all measure between 95-99 Ohms, or 101-105 Ohms.

i just tested a few tapes of 5% carbon films.  it is true that some of them have no resistors within 1% tolerance.  but only because the entire tape is at -2±1%.

the idea of holding back the best resistors would only make sense if the yield at 1% did not meet demand otherwise.  even if this were true in the past, i doubt it is now.  there is not much premium on 1% tolerance.

also, 5% resistors should be manufactured in E24 values and 1% resistors in E96.  so a bunch of 5% 470s would have gaps around 464 and 475, but not necessarily at 470?

incidentally, does anyone have any theories on how the ranges below E48 came to be rounded wrongly?  if you work it out (10i/6, i=6..11), E6 should have been 10:15:22:32:46:68.  i have never found any explanation of how the values 33 and 47 came to be used instead.
 

Offline Simon

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Re: Resistor Question
« Reply #14 on: October 08, 2010, 06:30:30 am »
what you also need to remember is the fact that the tolerance may vary during use and with age, you could buy a 5% resistor, find it to be bang on but then push it to near it's max wattage/tamp and find the value change to 4% ? Always remember that what you staticly measure under what are fairly controlled conditions may vary with use
https://www.simonselectronics.co.uk/shop
Varied stock of test instruments and components including EEVblog gear and Wurth Elektronik Books.
Also, if you want to get ripped off: https://www.ebay.co.uk/usr/simons_electronics?_trksid=p2047675.l2559
 

Offline orbiter

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Re: Resistor Question
« Reply #15 on: October 08, 2010, 11:29:33 am »
And if you want to TOTALLY geek-out on resistors ...  :) ...

Basics of Linear Fixed Resistors

That's a very helpful and interesting article JohnS, thanks ;)


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