Buying resistors for Arduino

Hey folks

Since i started using arduino (''learning'' to be specific), i noticed for every project you need to use resistors (at least in projects when i used LED and potentiometer). Usually Arduino kits comes with 220ohms, 1k,10,12k etc.

So, i was wondering what do you think about what Ohms values of resistors do i need most during simple projects. By simple , i mean you use lot of LED, sensors and stuff that can be found in Starter kits. I wanna stock up some resistors of different values and i need to decide what values do i need most ? I am not going to solder in near future so i would buy 10-20 of most required value just to have it around. When i start to learn how to solder and stuff, i will buy more. Or should i buy every possible value there is, because they are cheap and figure out in future what i need. But there are around 100 values in my shop and buying 20 of each would cost me 30e. I am not kind of person that is willing to take a walk to nearest shop (which is 20 mins by bus) every time when i need something and that thing costs pennies. So what is your experience ?

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Boy this is an opinion question if there ever was one. :slight_smile:

I see two cases. One with a small selection one with a large.

For the small selection I would pick 3 resistors per decade (i.e. multiples of 10).

10, 20, 50, 100, 200, 500 ...... up to 2 meg. (the 20 could be 21 or 22, the 50 could be 47 or 51 exact values usually don't matter.)

For the larger selection I would purchase a Kit on ebay. I don't have one in mind but I've seen them there.

Good luck

John

You can get 1000 resistors of the E12 series for $3 on eBay. On top of that, I'd recommend a couple of strips of 270Ω resistors for LEDs. That'll set you back around $5 total if you know where to look and don't mind waiting a week or two for shipping.

When you are starting out, the plethora of resistance values will seem extreme. Like, who would ever need a 90K resistor!? So start with just a few and combine them to get different values. Once you get the feel for what you need, get those.

I would start with some 100, 1000, 10000 resistors. These will work with most simple Arduino projects. You can get double the resistance by putting two in series, or half by paralleling them. In general use 100s with LEDs to make them extremely bright, 1000 if they should be quite dim, and 10000 to pull pin voltages up or down for switches, sensors, communication lines, etc.

ChrisTenone:
In general use 100s with LEDs to make them extremely bright

That'll quickly wear out your typical 1.7 - 2.1 V red, green or yellow LEDs.

ChrisTenone:
When you are starting out, the plethora of resistance values will seem extreme. Like, who would ever need a 90K resistor!? So start with just a few and combine them to get different values. Once you get the feel for what you need, get those.

I would start with some 100, 1000, 10000 resistors. These will work with most simple Arduino projects. You can get double the resistance by putting two in series, or half by paralleling them. In general use 100s with LEDs to make them extremely bright, 1000 if they should be quite dim, and 10000 to pull pin voltages up or down for switches, sensors, communication lines, etc.

Thanks for the tips. I thought the same but i am noobie when it comes to this. Also i checked aliexpress which i use for my regular online shopping, there are a lot of good offfers when you buy as a kit. I will stock up some basic values and figure out what i need.

PieterP:
That'll quickly wear out your typical 1.7 - 2.1 V red, green or yellow LEDs.

Makes sense. I usually take 220R or 1k for each project (i mean, i have 4 values in my kit soi dont have many options hah). But i keep experimenting with LED and their V values.

I guess it depends on what you are in.

+++

Myself I am into LEDs, sensors, renewable energy - so far. Learning by doing :-).

In my case lower values (up to 1 K) are more usual. And I need more values in the lower end (10-600 Ohm) comparing to higher end (above 600 Ohm).

So i got some 100 pcs 220 Ohm comparing to only few above 10K in each value.

I also brought an "assortment" of resistors of general use (some 600 pieces, in double decades), ending in filling my boxes with values I think I will use - maybe - in one year or more from now. Or never. OK, they are cheap. But the negative impact is that they are many.

+++

Another thing I found useful is a 4 bucks multimeter. Certainly, the accuracy is acceptable at best. But is light, easy to use and no cry if damaged.

To measure resistors I use this one (faster than reading color codes or staring on very small figures of small strips; well sometime I will classify them - maybe :-)). Multimeter also useful for some on-spot operational measurements.

For critical measurements I use another multimeter, which is more expensive.

For use in solderless breadboards, don't buy resistors less than 1/4 Watt, the leads are too skinny for easy insertion in breadboards. I would start with all 1/2 Watt until you get the feel for it.
I like this one:

It has mostly already been said. For normal arduino digital circuits you need pullup resistors (say10k), led current limiting resitors (220 ohms),
pin protection and transistor base resistors (say 1k). For other purposes, eg voltage dividers, resistors for multiple buttons on 1 analog pin etc. etc. etc. a selection pack should do.

I don't even have the luxury of an components shop within a 20 minute bus ride so my policy is to keep a large stock of cheap modules and components (mainly from direct from China - free postage, no minimum order value but up to 4 week delivery time) and use a next day delivery service for exotic or urgent items ( significantly more expensive!).

A while back I bought a kit of 30 values, 20 pcs of each, 1% tolerance for the equivalent 3-4 Euro or so off Taobao. You'll be able to find similar sets on Ebay, Aliexpress, Amazon, etc. Great value for money, and a great range of resistors, it ranges from 10Ω to 1M or so.

On top of that I have a 1000 pcs bag of 10k (used all the time for pull-up resistor and so), and a similar bag of 330Ω resistors (using those all the time for LEDs - so they take about 5 mA at 3.3V supply). Those bags cost the equivalent of about 1 Euro each.

All 1/4W resistors, for most applications that's more than enough.

Such a set will last you for VERY long and you will always have the correct value at hand (or be able to create it with two parallel resistors if you really need a specific value). And if you find you really need a lot of a specific value, order more of those as you go.

Now you're at it, it's maybe a good idea to get similar kits of capacitors. A set of ceramics (a range of 10p-4µ7 or so with extra 100 nF ones as those you need all the time for filtering), and a set of electrolytics or tantalum (1µF-470µF covers most use cases).

I also have the policy of ordering at least double the numbers that I need. E.g. when I need a specific sensor or IC, buy two or three of them. This as you may break one, and very good chance you'll come up with another project that needs the same one later.

@Wvmarle: very effective procurement "policy"!

I will check whether I can buy components in bulk of 1000 pcs myself.

And also a good hint for capacitors. Today (Sunday) I needed a 1 uF capacitor. Because I do not have that value I used a 10 uF capacitor, which hopefully did its job. I spotted a set of various capacitors that fits my habitual scope of work.

I'm often buying resistors off Taobao (most shippers are in Shenzhen, nice and close by for quick & cheap shipping), and the problem I often encounter is to find smaller quantities than 1,000 pcs... even bags of just 100 pcs are quite hard to find... other than in the multi-value kits, that is. Resistors are just so cheap.

Liggy:
Since i started using arduino (''learning'' to be specific), i noticed for every project you need to use resistors (at least in projects when i used LED and potentiometer). Usually Arduino kits comes with 220ohms, 1k,10,12k etc.

Ebay and co ..... just search for something like: "(1.2Ω–1M Ω) 500pcs 50 Values 1/2W 0.5W 1% Metal Film Resistors Assorted kit Set"

When I started without much of a clue what to have - I got an assortment from Sparkfun then as I started to use them got more of what I used - or in the case of needing resistors to make some LED's bright I used the assortment to get me close and bought 100 of about 8 different values in the rough value I thought would work and tried different values to get the 18 or 19 ma I wanted.

You could just have measured the voltage drop over the LED and then calculate which resistor value you need for the desired current. Much easier.

I did the calcs from the data sheet and missed something - so thus the bracket the values, and at the cost for a 100 roll was not too bad, maybe measuring the voltage drop and supply voltage would have been another way, was last year so don't remember all what I tried - also using a chip that sank the current so did not have 5 v available

Also seems to me the LED's had a curve for the current and the limited data sheet I had did not show the curve, just the nominal voltage drop

But I will give your suggestion a try on the next project

thanks

As with all diodes forward voltage will go up a bit with increasing current - they're not ideal components.