I can't find a 10K resistor with 1/4 watts at my local store is there a problem if i use a 1watt 10K resistor ?
Hi Air, and welcome to the forum :)
You sure CAN use a higher wattage resistor, any time...only restraint is the space you have on your board. Of course at some point it becomes ridiculous, but if that's all you have, go for it!
Of course you don't want to go the other way, for example using a 1/2W when a 1W is called for, but I didn't need to tell you that :)
PS - if you CAN get 1/2W resistors or what have you, locally, you can put two same value in parallel with each other to get 1/2 the resistance....two 22k/10% resistors in parallel will give you ~11K, which is close enough usually.
What are you making?
Thanks for your quick reply gibson it's nice to be here i'm just getting started :)
i guess i ll go with the bigger wattage resistor cause space is not an issue for my project.
I found another problem though i want an 2.2M resistor but can't find that one neither.I could go with a 2.7M or put in parallel two 10Mohm resistors(that's the closest i can get :P)
BTW my project i chose to start is the one from premier guitar https://www.premierguitar.com/articles/21291-build-your-own-stompbox?page=1
Quote from: airguitar on December 05, 2017, 03:23:37 PM
Thanks for your quick reply gibson it's nice to be here i'm just getting started :)
i guess i ll go with the bigger wattage resistor cause space is not an issue for my project.
I found another problem though i want an 2.2M resistor but can't find that one neither.I could go with a 2.7M or put in parallel two 10Mohm resistors(that's the closest i can get :P)
BTW my project i chose to start is the one from premier guitar https://www.premierguitar.com/articles/21291-build-your-own-stompbox?page=1
You'll actually be closer if you parallel one 2.7M with a 10M for 2.176M. 2.7M is probably close enough for dirt, if you're trying this on a breadboard you can experiment with the change in sound of the resistors you already have.
thanks i ll go for it and see the results
Short of resistors that determine how much juice an effect draws from a power supply, most of the things we build or repair/mod here can work with resistors as low as 1/8W. Keep in mind that the wattage rating is an indicator of how much heat it can dissipate before turning into a fuse and going "poof". The surface-mount resistors we often see in effects these days are even lower wattage-rated, but as far as through-hole parts are concerned, 1/8W is likely as low a value as you'll find.
As has been noted by others, use of a higher-wattage rating simply means you may have difficulty fitting it in the available space.
Sometimes one can cope with that by simply mounting the resistor vertically (i.e., one end lead gets bent completely 180-degrees). Just keep in mind that when such resistors end up being "tall", there is a risk of shorting out the exposed part of that bent lead against the back of a pot or some other conductive surface. Happily, that can be remedied by simply planning out where panel-mount components are to be installed, so as to avoid such mishaps. And of course, if your next available opportunity/order provides you with the lower rating called for originally, one can always stick in a smaller wattage unit.
Welcome to the Hotel California. :D
Buying one resistor at a time is going to be expensive and frustrating. While you may not (yet) have your sights set on building hundreds of pedals, it's fair to say that you might unwittingly find yourself building one or two (or twelve) more after this initial foray [see paragraph #1]. So try to buy stuff a bit more "in bulk". The unit cost will fall dramatically and you'll be able to do it mail order and the postage won't be 800% of your purchase. And just by luck, there's a 15% coupon current right now (http://www.diystompboxes.com/smfforum/index.php?topic=104322.msg1112116#msg1112116) at our favourite far-eastern discount component emporium - Tayda (http://www.taydaelectronics.com/). (And for when you need more specialist parts - and I assume you're in the US - then head over to our also-favourite ursine purveyor (http://www.smallbear-electronics.mybigcommerce.com/) of DIY bits and pieces, Smallbear.)
Have a bit of search on the forum for "what components should I buy a dozen of?" threads - there are plenty of them. Then get your order in before COB on the 8th! ;D
Yes, see if you can buy a whole pack of resistors, Air!! You'll want to get lots of the recommended parts, because you will be addicted to this soon!
Of course, resistors in series just add...so, 10K and a 4.7K = 14.7k.
The way to come up with odd values of resistance with 2 resistors in PARALLEL using what you have is this formula, which is how Wavley got his answer:
R1XR2 / R1 + R2 which is also called "product over sum", and is used for only 2 resistors in parallel.
10M * 2.7M = 27M , then divided by 12.7M approx = 2.2Meg (close enough for our non-precision purposes)
You will pick this up as you go along :) Basic electronic tutorial are all over the net, check some out!
Happy building.
I use an app called ElectroDroid (for Android OS) to quickly figure out what combination of resistors I need for a particular oddball/out-of-stock resistance value. It's been quite handy. Here's a screenshot example:
(http://i.imgur.com/Q6gAfoPl.jpg)
> i want an 2.2M resistor but can't find that one neither.I could go with a 2.7M
That's usually fine.
Here it is entirely fine. That circuit is very self-compensating.
High value resistors are rarely used for their "absolute" resistance rather than "relatively huge" one..
(in the way they are more of "voltage carries" than "current limiters"..)
Using a calculator like Eric showed is really the way to go...doing it by hand can be very frustrating! Mentally figuring to get "1/2" or "1/3" isn't too bad, but for really interesting combinations, it could hurt your head, ha ha...
Try doing it for THREE resistors in parallel! ;) That's why in the long run it's simpler to buy about THREE full sets of resistors - you won't face this issue for a LONG time...
If you can't find a 10K ¼ watt resistor at your local store......
Find another store!
The resistor you are "searching" for is one of the most commonly used values and sizes.
Tell us where in the world you are located, and maybe we can suggest other options for your electronics shopping pleasure.
> Using a calculator like Eric showed is really the way to go...doing it by hand can be very frustrating!
> Mentally figuring to get "1/2" or "1/3" isn't too bad, but for really interesting combinations, it could hurt your head, ha ha...
> Try doing it for THREE resistors in parallel!
Disagree. Figuring parallels SHOULD be a basic builder skill. Like a soldier figuring rifle windage, a guitarist slicing chords, a house framer figuring rafter lengths, a logger figuring a drop.
A calculator with a 1/x key is ample. While $1 4-banger calcs don't have this (you can do it long-ways but that's tedious), all PC/Mac and cellfone app calcs have a "scientific" mode. I keep a $11 TI-30 right-at-hand.
Of course when not feeling too sharp, *series* resistors are easier to figure and cover most cases.
VERY Off-Topic for this forum: Doug Self has posted tables to look-up odd values as combinations of standard values.
http://www.diyaudio.com/forums/analog-line-level/315269-willmann-tables-available-douglas-self.html
Sure, Paul, I agree that being able to figure out parallel combinations with a simple 1/x calculator is critical to understanding electronics, but once you've got over, say, 1,000 of those calculations under your belt, it is ok to reach for quick convenience.
Besides, with a soldering iron in one hand and a beer in the other, a simple app is potentially less work for my toes than a TI-30 would be. :icon_razz:
@airguitar: You can easily imagine how things would result if you haven't verbalize such a make do with "Yes/No" question.. :icon_biggrin:
Quote from: PRR on December 07, 2017, 11:45:35 PM
> Using a calculator like Eric showed is really the way to go...doing it by hand can be very frustrating!
> Mentally figuring to get "1/2" or "1/3" isn't too bad, but for really interesting combinations, it could hurt your head, ha ha...
> Try doing it for THREE resistors in parallel!
Disagree. Figuring parallels SHOULD be a basic builder skill. Like a soldier figuring rifle windage, a guitarist slicing chords, a house framer figuring rafter lengths, a logger figuring a drop.
A calculator with a 1/x key is ample. While $1 4-banger calcs don't have this (you can do it long-ways but that's tedious), all PC/Mac and cellfone app calcs have a "scientific" mode. I keep a $11 TI-30 right-at-hand.
Of course when not feeling too sharp, *series* resistors are easier to figure and cover most cases.
VERY Off-Topic for this forum: Doug Self has posted tables to look-up odd values as combinations of standard values.
http://www.diyaudio.com/forums/analog-line-level/315269-willmann-tables-available-douglas-self.html
Well, I suppose, Paul...I know I have no trouble finding the resistance of say 4 R's in parallel, and wouldn't bother go lookup a calculator online for that, it would take longer than figgering...but rearranging the eqn to set myself up for "how can I get X resistance using these 4 resistors?" is WAY more than I want to do! It's the box on there that says "enter desired value" that I find attractive ;) Honestly don't think I've ever gone that route, though.
Yeah, I do agree that everyone should know "1 / 1/R1 + 1/R2 +.....1/Rn " and what it's for. Looking at a schematic, you won't always have an online calculator (or ANY calculator, maybe!). Like Eric said, then you get 1,000 down, maybe it's ok to toss #'s into an applet if you want, but never be dependent on it, no no.... 2 cents....
Quote from: EBK on December 08, 2017, 05:39:41 AM
Besides, with a soldering iron in one hand and a beer in the other, a simple app is potentially less work for my toes than a TI-30 would be. :icon_razz:
eric, I thought you worked the scissors with your feet.
[too_cents] at times, I spend far too much time playing at parallel resistor calcs, but only ever w/ a calculator and 1/x. I wonder why anyone would need [the precision of] three resistors in parallel, except for power rating. [/money_back]
Quote from: duck_arse on December 08, 2017, 08:55:40 AM
eric, I thought you worked the scissors with your feet.
I tried, but I think those scissors were made in Soviet Russia. :icon_wink:
Six days later, I can finally wear a regular shoe on my right foot. :icon_cool:
Quote from: PRR on December 07, 2017, 11:45:35 PM
> Using a calculator like Eric showed is really the way to go...doing it by hand can be very frustrating!
> Mentally figuring to get "1/2" or "1/3" isn't too bad, but for really interesting combinations, it could hurt your head, ha ha...
> Try doing it for THREE resistors in parallel!
Disagree. Figuring parallels SHOULD be a basic builder skill. Like a soldier figuring rifle windage, a guitarist slicing chords, a house framer figuring rafter lengths, a logger figuring a drop.
A calculator with a 1/x key is ample. While $1 4-banger calcs don't have this (you can do it long-ways but that's tedious), all PC/Mac and cellfone app calcs have a "scientific" mode. I keep a $11 TI-30 right-at-hand.
Of course when not feeling too sharp, *series* resistors are easier to figure and cover most cases.
VERY Off-Topic for this forum: Doug Self has posted tables to look-up odd values as combinations of standard values.
http://www.diyaudio.com/forums/analog-line-level/315269-willmann-tables-available-douglas-self.html
I had a professor explain why he encouraged calculators in class when we got a little more complicated. "You wouldn't go to a job without a multimeter, why on earth would you go without a calculator"
There are a few things you should be able to calculate and this is one of them, series caps is another good one. Not that I don't cheat every now and then and use an app (which I've recently removed all of from my phone because it's full of amp and kid pictures) but it's a good thing to be able to do a bit intuitively, especially when you're standing in front of the parts drawers at Radio Shack on a Sunday because you just need to fix a studio monitor that broke in the middle of a mixdown session and you used most of your resistors building a Ludwig Phase II... which is a real situation that can happen.
In my first undergraduate Physics class, the professor banned calculators, and we had to be able to estimate square roots as we calculated everything by hand. The tests were multiple choice, with answer choices like:
A) 3.27 m/s
B) 3.46 m/s
C) 2.97 m/s
D) none of the above.
One day, a frustrated student asked the professor why we couldn't use calculators when in the real world we'd be allowed to.
The professor gave an awesome answer to this, which was a very valuable lesson. He said, "I've got news for you. You are already in the real world. Right now, your real world is my Physics class."
Quote from: EBK on December 08, 2017, 09:54:25 AM
In my first undergraduate Physics class, the professor banned calculators, and we had to be able to estimate square roots as we calculated everything by hand. The tests were multiple choice, with answer choices like:
A) 3.27 m/s
B) 3.46 m/s
C) 2.97 m/s
D) none of the above.
One day, a frustrated student asked the professor why we couldn't use calculators when in the real world we'd be allowed to.
The professor gave an awesome answer to this, which was a very valuable lesson. He said, "I've got news for you. You are already in the real world. Right now, your real world is my Physics class."
Certainly, if you're doing something inherently math based you should definitely have a good handle on the basics and be able to do it by hand and I'm sure that's the lesson the professor was actually trying to teach. It seems like the real life lesson I learn by that statement is that someone in control of your working parameters can force an arbitrary rule on you, which is also a lesson you should learn. ;D
I work with a lot of Astrophysicists and research engineers and I can pretty safely say "show me a physicist that says they're not using Matlab (or some other computer simulation/calculation software) and I'll show you a liar"
> "You wouldn't go to a job without a multimeter, why on earth would you go without a calculator"
My body can sense voltages but VERY imprecisely over a narrow range-- my built-in calculator can do many square-roots and some one/over problems closer than 50% (better than 10% with pencil).
> why anyone would need [the precision of] three resistors
Phono preamps. There is a 2-R 2-C network for a lumpy-falling response. If the values are not "correct", the response has "errors". Some people get very obsessive about this. Like a +/-0.01dB phono curve could make up for the crap on commercial LPs and the "creative" tweaks in mixing and mastering.
With 1%-series resistors it is hard to see how you could ever "need" more than two maybe three to hit your target close-enough for any audio purpose. I think Willmann just got into the problem and compiled the 2 3 and 4 R tables to be thorough.
Quote from: PRR on December 08, 2017, 10:23:46 PM
> "You wouldn't go to a job without a multimeter, why on earth would you go without a calculator"
My body can sense voltages but VERY imprecisely over a narrow range-- my built-in calculator can do many square-roots and some one/over problems closer than 50% (better than 10% with pencil).
That's a pretty good point, and I'm a pretty big believer in being able to do all the common formulas by hand (or in your head), but reality is that I'm a middle age man with two jobs, a three year old, and a rock and roll youth, my calculator rarely leaves the vicinity of my meter, scope, and soldering iron :D
E192 series overcome all the above issues..
(and you can count on 0.5% tolerance for some "intermediate" values, if you're such a circuit designer purist :icon_biggrin: or just proceed to 0.1% tolerance and don't bother with series/parallel combinations anymore..)
P.S.
I'm waiting for Sir Mike (or any other reactionary fellow :icon_lol:) to come and ask what about if you need a high wattage specific value resistor.. :icon_redface:
Quote from: antonis on December 14, 2017, 07:00:50 AM
E192 series overcome all the above issues..
(and you can count on 0.5% tolerance for some "intermediate" values, if you're such a circuit designer purist :icon_biggrin: or just proceed to 0.1% tolerance and don't bother with series/parallel combinations anymore..)
Or, if you want fewer part drawers, you could use 20% tolerance resistors and keep measuring until you find one
just right. :icon_razz:
Quote from: EBK on December 14, 2017, 07:54:03 AM
Or, if you want fewer part drawers, you could use 20% tolerance resistors and keep measuring until you find one just right. :icon_razz:
And result in a dead-empty battery, 'cause the parts getting closer to their nominative value are set in another (narrower) tolerance class.. :icon_wink:
Quote from: antonis on December 14, 2017, 08:02:43 AM
Quote from: EBK on December 14, 2017, 07:54:03 AM
Or, if you want fewer part drawers, you could use 20% tolerance resistors and keep measuring until you find one just right. :icon_razz:
That should be hopeless Eric, 'cause the parts comming closer to their nominative value are set in another (tighter) tolerance class..
No, I meant if you needed something like 115k, you'd just measure your 100k pile until you found it. :icon_wink: (although, I wouldn't have time for such an approach, and I imagine the values would be somewhat Gaussian-distributed, making this doubly impractical)
Didn't anyone ever told you NOT to respond with quotation during quoted person editing..??? :icon_lol:
If they indeed are Gaussian distributed they exhibit high-degree predictability so you can set a formula for the less actions (measurements) till goal..
P.S.
Maybe it's time to go for lunch and save myself from been a banned spammer.. :icon_redface:
I can go back and edit the quote if you want. No one would ever know.... :icon_lol:
Quote from: EBK on December 14, 2017, 08:33:51 AM
I can go back and edit the quote if you want. No one would ever know.... :icon_lol:
if'n you did
this, it might flush out one of those reactionary types antonis
* was seeking earlier.
* antonis - noted spammer, recently banned.
What about if you need a high wattage, specific value resistor?
* I will assume being talked about means that I have 'arrived' on the social scene? :icon_lol:
> if you needed something like 115k, you'd just measure your 100k pile until you found it.
Best-case, the manufactured values are utterly random, and given a large enough barrel, you will find a 115K.
As manufacturing improved, values clustered around nominal, Gaussian trend, and parts in the crack got harder to find.
Worse than that: we didn't have sub-penny resistors, no deep barrel to sort through. Then you take a file and work-down a 100K into a 115K. Dab of nail-polish to seal the raw carbon.
Quote from: armdnrdy on December 06, 2017, 11:50:27 AM
If you can't find a 10K ¼ watt resistor at your local store......
Find another store!
That's assuming you actually have a local store to begin with. The cheapest possibility to get hold of a 1/4W 10k resistor anywhere close to me is about $12USD, I'd get 20 each of 30 different values. Not bad looking at the total value but for the one resistor I need it's expensive and that money could buy a lot of stuff from Tayda.
I can also travel a bit (not that far but more than an hour off track as opposed to on my way home) and buy a single carbon comp resistor for about $0.1 or a metal film for $1.5. They have cheaper metal films, but not in store at the moment (estimated delivery in 11 weeks).
Quote from: Perrow on December 15, 2017, 10:28:22 AM
a metal film for $1.5
:icon_eek: :o
They probably are Uppsala Seismologiska Unstitut sole supplier..
Quote from: antonis on December 15, 2017, 11:21:37 AM
They probably are Uppsala Seismologiska Unstitut sole supplier..
That's actually probably true, they are the "go to" supplier in Sweden, they are in Stockholm though (as I am most days but not nights).
My favorite institute of Uppsala is the geological, they've promoted themselves with the slogan "Geology, the foundation of everything" which I find hilarious.
Way off topic...do you know Stevie Klasson?