What to keep on hand?

I’m just starting out with Arduino projects, and I was looking for some advice as to what components I should keep on hand.

I know that the components will be based off of the type of projects I decide to build, but I’m talking about common components.

For example, what size resistors should I keep on hand? Are there any common sizes that are good to have on hand?

Are there any other components I should keep on hand? What do you keep in stock on your workbench?

I plan on powering my projects with 9V power supplies or batteries. I think that might factor in to the size of resistors I should keep on hand.

I know project-specific components I will have to order as I need them.

I guess I’m just trying to get some idea of what to keep on hand, because I noticed I get huge discounts by buying components in bulk, so I think it’s silly to buy 10 resistors or what ever at a time, when I can huge discounts for buying 1,000 at a time.

Plus I don’t want to be ordering things and waiting (or paying) for shipping every time I want to do a simple project.

Radio Shack sells a resistor assortment pack, has been a good range for me so far. The Radio Shack capacitor assortment pack sucks though.

You may find this thread informative:


my three top choices.

#1) catalog,
#2) internet
#3) credit card.

from there, you get everything you need for parts.

I would suggest you get 10 of these:

most work is done at 5 volts.
leds, resistors, figure for 5 volts.
needs pull ups. 1k, 10k, and 4.7k
pn2222 transistors
2n7000 mosfets
diode 1n4002
10uF/25V. caps
0.1µF and 1µF caps
some tact switches

the problem with ordering in bulk is that could get 100 LED's to find you needed the smaller ones.

if you start with an array of parts, keep notes of each circuit you look at and may want to build, write down the parts.

if you find you need lots and lots of tiny yellow LED's then get the larger quantity and double as many resistors.

as you use stuff fast, buy next quanty up lots, 25 next time, or 50.
get storage boxes or trays.

once you get a feel for what you are doing and what types of projects you want to do, just order more suff.

e-bay offers perf boards, so if you want to make a permanent project you can make on one of those.

Ok, Thanks.

I guess as I get better at this, I'll start to get a better idea of what I use the most.

Not that I have one, but something like this may be handy.

I do have one of these.

If you look at dipmicro.com, you'll find a lot of what you need.
Also taydaelectronics.com
Not such a huge variation in parts that you get lost finding stuff.
Afterwards, get comfortable finding parts at digikey.com and mouser.com

A lot of resistor and capacitor packs have values you'll never use unless you are doing some detailed analog stuff with op amps.
9V battery is a waste most of the time. Not enough current capacity, you waste half the voltage heating a regulator to make 5V, and its not enough voltage to drive a 3 LED string. Better off with 12V for LED strings, and 3 AA type batteries for the digital stuff, 4AA for powering motors & servos.
I keep 0.1uF, 22pF, 16 MHz xtals, boards to make prototypes on, wirewrap sockets, 1K, 2.2K, 5K, 10K resistors. Small signal diodes. TPIC6B595 shift registers, and 328P and 1284P microcontrollers. LEDs. 220 and 470 resistors.
Note: I am also an EE and have been accumulating parts for years. Best bet is to get what you need for a project, and order extras.
I love wirewrap for prototypes, point to point soldering sucks and takes a long time.
www.phoenixent.com, stock up.

Old printer circuit boards and sterios have a good assortment of parts.
Tredmills have displays and power supplies/contollers for a pretty powerful DC motor.
Keeps some boards around and get a solder sucker.

I'll chime in and mention a couple extras beyond the basics (resistors, capacitors, etc) that end up making life so much easier.

Jumper wires - Determine how much you think you'll use, then triple it...

breadboards - Get a minimum of 3.. Get a couple of the smaller little rectangle ones too.

Arduino - at least 2... I prefer the mini's and nano's. I have about 20 of them.

Definitely get a handful of each: NPN bipolar, PNP bipolar, N-channel mosfet, & P-channel mosfet. For "general purpose use" I'd choose ones that can handle 1A continuous current.

Order a couple small piezo buzzers too. They come in handy when you want a confirmation of action on projects. Example use would be, if you've programmed a tactile button to change a setting, and you're not seeing a result, you'll at least know your button is working if it beeps lol.. Basically they're great for debugging things.

You'll use batteries to power your projects a lot less than you think... If you are focusing on battery powered projects, I'd stick with 3.7v lithium, pretty much the standard for battery powered circuits now-a-days and they come in all shapes and sizes all the way down to coin-cell size. It's a short buck down for a 3.3v circuit and easy boost up to a 5v circuit, or you can even power a 3.3v project unregulated if you're feeling gutsy...

Oh yea, and a voltmeter is a must. Or 2 or 3, sometimes 4 haha.

Oh, and one more thing... Get at least one HC-05 bluetooth module for programming / communication. You can find them on Ebay for $5-8 bucks.

This was one of those things that made my life so much easier when dealing with arduino. Not having to have my project or the arduino tethered to my computer. With this nifty lil breakout board you can program and communicate wireless over bluetooth. So if you want to make a change to a program you have running, upload a new sketch, communicate, or read serial data, you can do it without moving your project. Another good thing about it is that I made it so I can open the serial monitor without it reseting the arduino. You can also pair it with your phone and read/write serial data with your phone.

You can see in the picture below, I made it where it's plug and play to a pro mini or nano and is powered by a small coin cell rechargeable 3.7v lithium battery.

Oh, and one more thing... Get at least one HC-05 bluetooth module for programming / communication. You can find them on Ebay for $5-8 bucks.

Hi Gabenix, I looked into BT modules a while back and came to the conclusion/was told that they could not be used for remote programming Arduino. So this is interesting news. Can you give a link to a good tutorial or something on this please?


perhaps you can buy some kind of "starter-kit", with a few caps, resistors, leds,....
it helped me alot!

Hi Paul... To be honest I couldn't find any tutorials to explain how to program/upload sketches with the HC-05. In fact, the conclusion you came up with is in-line with all the information out there. But it's actually an extremely simple solution.

The only thing that keeps the HC-05 from uploading a program to arduino is that it doesn't have a DTR (Data Terminal Ready) pin which tells the arduino to reset and accept a new sketch.

The solution is to re-purpose the "state" pin (PI09) on the breakout board. It's purpose is to attach to an LED and indicate the connection status. It's default setting is to send the pin HIGH when a connection is made, but you can simply enter into command mode of the HC-05 and use an AT COMMAND to tell it to send the pin LOW when a connection is made.

Voila! In about 1 minute of time you have successfully re-purposed the LED pin to a DTR pin which will reset your arduino to accept a new sketch when you hit the upload button.

A couple things to note... This will work for a pro-mini without additional hardware by connecting to the DTR pin. If you're using an UNO or similar, you will need a capacitor in between our custom "state" pin and the reset pin on the uno. The reason is that the HC-05 will drive our custom pin LOW for the entire connection which would essentially be the same as holding the reset button the entire time. Having the cap in between solves that problem.

It a quick easy fix, takes about a minute to do. It's just a lot harder to explain the steps to do it in a couple sentences.

Here's a link to the AT COMMAND set ---> Robopoly ‐ EPFL

and here's a link to a tutorial, video, and sketch on how to enter the AT COMMANDS. ---> Modify The HC-05 Bluetooth Module Defaults Using AT Commands - TechBitar

Hope this helps answer some questions...

I second taydaelectronics.com as a good resource for cheap parts to stock.

Thanks for all the replies, this helps a little for me getting started.

I am confused about one thing though, once I build a project, what do I do with it? I mean, I see all the project kits you can buy online and they all have cases or something, like one is a calculator. Once I build a project, then transfer it from a breadboard and solder everything up, how do I get a case for it, or something to put it in? Do I have to make something like that?

I know that Arduino could be damaged by ESD… So I don’t think I’d just want to have my project laying around. I’d want to box it up so that it could be used without worrying about damaging it.

A clock kit I found comes with a case like this (attached).

@CrossRoads: You said that 9V batteries can’t carry enough current. I just bought an AC adapter for Arduino which is 9V and 1A… is that going to be enough? Is it better than 9V batteries?

Problem with those little PP3 batteries is not necessarily the current they can provide, but that they can't provide it for very long. Battery capacity is measured in, for instance, mAh (milliAmp x hours) which is a measure of its energy rather than its power. They run flat pretty drastically.

(Power is volts x current, so for a given voltage, current is a proxy for power. Energy is power x time, so if current is a proxy for power, then current x time is a proxy for energy. )

For project boxes I like to use old cigar boxes found at fleamarkets or thrift stores. Easy to drill holes into.
This project is a temperature monitor.

I also have been liking these plastic boxes from Modern Device.

Personally, I use a 3D plastic printer for project cases, prototyping, and parts which is a luxury I’m thankful to have. But prior to having the printer I just bought sheets of acrylic from my local Lowe’s home improvement store and sandwiched finished soldered PCB’s in clear acrylic. It’s cheap, easy to cut with a razor knife, and you can make them any size you want. I think it looks pretty snazzy too.

Similar to these…

gabenix, please see this thread, I didn't want to hijack CSGuy's thread any further!

Those are pretty neat. I guess I think about it too much. I could use my imagination a little bit. The first picture that was posted made me think about using an old power supply box for one of my projects. I have an old 305W power supply from a old computer.

I could remove all the components from the case and reuse the case for one of my projects. It even has a place already for a fan to help move air and keep things cool. I think I could drill some holes in that pretty easy.

I know it can be dangerous to open those cases though. I'm not sure how to remove all the components safely.

I know it can be dangerous to open those cases though. I'm not sure how to remove all the components safely.

Only when, or shortly after, they are plugged in! As long as it has not been connected to the mains for 1/2 hr or so there is nothing to worry about.