Re: Resistor Size

[K3yPr0gg3r]

Hi,

I downloaded a Resistor Color Code guide to assist me with identifing the various resistors that I need while populating a PCB. I've noticed that in some build docs. I need an R value resistor, (i.e. 100R). I've checked the guide, and the colors of an R resistor and an ohm resistor are the same. So am I correct in assuming that a 150R resistor is the same as a 150 ohm resistor?

Thank you

[jimilee]

Jes!


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[davent]

The capital 'R' is an easy keyboard entry that sorta approximates the look of the ohm/omega sign, Ω, at least that's what i always figured.

dave

[BrianS]

One thing that I learned from a member on this forum was to check every resistor with my multi meter before using it in a build. Is it monotonous, yes (especially when you have a large resistor count), but it will keep you from potentially making a mistake. My rate of success on first time fire ups went up a lot after I started doing this.  I use a piece of styrofoam and line up the resistors according to the build doc and start measuring them.  It's pretty much fool proof if you go slow when you start putting them on the board.

[HamSandwich]

The capital 'R' is an easy keyboard entry that sorta approximates the look of the ohm/omega sign, Ω, at least that's what i always figured.

dave

I always thought R was just 'resistance', but your reasoning also makes sense.

[galaxiex]

Not to be too nit-picky here.... 

.... but resistor *size* could be mistaken as the physical size of the part, eg: 1/4 watt 1/2 watt etc...

What you are talking about is the resistor *value* 150 ohm, 120K ohm etc...

I'm not the parts police,  ... but I think it's good to get in the habit of having the terminology correct.

And to also answer your question as above, yes the capital R means ohms, so also yes, your 150R means 150 ohms.
The R is included to avoid a mistake such as using a 150K instead.

[AwesomeTyler]

I've got a question relevant(ish) to this:
As a noob that just bought a mountain of boards, I'd prefer to just buy everything I need in bulk order and get a real part organizer going. It's killing me though, I don't wanna order a ton of parts and get the wrong ones. Can 100k resistors be misconstrued in anyway? Mouser only filters by ohms, and I don't wanna accidentally order 200 100 milli or mega or kilo anything just to have a ton of parts I don't need. Is there a difference between 100k and 100K or any other variation I need to look out for or would each variation stand for a 100,000 ohm resistor? I know it's a dumb question, but we're talking about a ton of components here lol.

Thanks guys,
Tyler

[K3yPr0gg3r]

Tyler,

I'm going thru Mammoth for my resistors...the blue ones, (metal film), unless the build calls for the tan, (carbon comp). I've run into that on only one of my builds. Mouser can get confusing at times being new to building myself. Caps. are my biggest stumbling block. Once I have the correct value I just "bookmark" that page. I must have 30 to 40 pages marked in my pedal folder. You can also find components on Newark, Tayda Electronics (diodes, IC's and transistors), and at diyguitarpedals.com. The box caps are in nanofarads so NO conversion, and he has some hard to find components as well! Just FYI, those will be coming from Australia, but he gets stuff right out.
Hope this helps

[BrianS]

I would go to Tayda for your resistors and film box caps for just starting. It could be hit and miss with their ICs (I've gotten a couple of bad ones) and electrolytic caps.  Their resistors and box caps register just as good as the ones from Mouser (and someone will comment that the quality isn't as good and that could be very true) but for starting out it is by far the easiest and least expensive place to buy stuff. Sockets and potentiometers are good also. Once you get a handle on everything and what you want to stock up on then buying from Mouser, Allied, Newark, Arrow, etc....... Is the way to go when you can buy in bulk and get good pricing. One thing you have to watch out for is shipping costs. They will eat your rear end up.  Forgetting a part (and everyone does) can cost a lot or add time (waiting to order for another project) to building your pedal. If you get hooked on this (likelihood in the high 90 percentile) organization (spreadsheet) is extremely helpful.  Ordering from Mouser is pretty daunting for sure. But you will get the hang of it.

And Tyler the resistance filter at Mouser goes from ohms (which would be a 100r resistor on a build doc) to Kohms (100k resistor) to Mohms (1m resistor), etc... Hope this explains that for you.

[midwayfair]

Typical size of 1/4W resistors is 7.68mm. But most of the time you can assume that they're that size. Manufacturers don't want to make their parts incompatible to existing parts libraries and PCBs. They want to make things easy on you.

[AwesomeTyler]

Thanks so much to the three of you. Very useful info.
Anything else I might wanna look out for whilst ordering a fully stocked organizers worth of components?

I'm here neatly not too ashamed to post links to what I'm about to buy before making the purchases. Or at least the cart.

Any reason I should go with high end stuff from Michael Percy or partsxconnection?

[AwesomeTyler]

I'm still very much looking into whether or not it's worth it to buy 'high-end' or 'audiophile' quality components for some pedals and which components would be worth having or even make any noticeable difference.

In-particular, partsxconnection has some resistors 'on sale' that have a were magnetic draw than typical resistors. Not sure if that's sales hype or not, but having components with a low noise-floor/less electro-magnetic field seems worthwhile.

There's also caps that go into the $50 a piece area (wtf?!). Not sure what using an oil filled cap would do to a pedal to affect tone..but at those prices, I'm not sure I even wanna know.

[davent]

I would think the coveted amps and pedals of yore were made with the very cheapest parts available to the makers at the time of manufacture. Do we want cleaner dirt or dirtier dirt?

dave

[AwesomeTyler]

I would think the coveted amps and pedals of yore were made with the very cheapest parts available to the makers at the time of manufacture. Do we want cleaner dirt or dirtier dirt?

dave

Well, that's assuming we want dirt at all in this case. Obviously dirty is a slightly different story, albeit not entirely. I still hate that I can't gig with a Big Muff in venues larger than a small dive bar due to the sheer volume of the noise on a dimed amp.

I'm looking more into effects that perform a specific duty and need to perform as 'dead-on' as possible (ie. Delays, filters, mod). If shinier components will help it do it's job as expected time and time again or lower unwanted ambient noise, then shinier components it will get (within reason). If we're talking about to small of a difference for it to ever make a noticeable difference, I'll stick with building $30 a pedal.

-Tyler

[BrianS]

What Dave said is probably very true.

I was at a very well know commercial pedal makers shop last year and was talking with one of the employees and asked where they got there 3pdt stomp switches. His reply, the cheapest we can find.  I was a little in awe because the b stock pedal I purchased cost $165. If you are looking to fine tune your parts I believe the audio path is where most put the high end caps and parts. I'm not an electronics expert but a 1 cent 10k metal resistor that measures 10k on your multi meter should be just as good as a 50 cent one. It may not have the longevity of the 50 cent one but In my case that resistor will probably last for as long as I need it to. Also take into consideration the amount of power going through the pedal. In most cases it's not very much. Not a tremendous amount of push on the components. Again, and I'm not being a smart a--, it's ultimately your money and if it puts you in the comfort zone then go for it.