# Which electronics components should I always have on hand?

I am thinking about ordering up some parts for every day use. I am thinking about making one big purchase so as to minimize on shipping and other charges.

What are some of the components that any electronics hobbyist should have around ALL the time?

To put a little more scope: typically working with Arduino's, PICs and sensors. 5V - low current projects.

Looking for: component, value or range (if any), manufacturer (optional)

For example - Resistors, 1K through 100K 5W

## locked by KortukNov 15 '11 at 23:59

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• I wonder if this could be made a wiki, incorporating answers with a minimum number of votes. Disagreements can be settled by duel. – tyblu Dec 2 '10 at 11:22

Here is my general collection. Apart from the components listed below, when ever I by parts I usually by a few extras. It doesn't take long to build odds and ends that way.

• 1/2 W 1% Metal Film Resistors. All E12 values between about 100 R and 1 Meg. Random collection of values in 5W.

• 1, 10, 22, 33, 68, 100, 220, 330 nF 63 V film caps. A random assortment of electrolytics - 1, 10, 100 uF in voltages between 16 V to 63 V. A hand full of different value ceramics less than 1 nF.

• General purpose PNP and NPN transistors. I typically have BC337/327s laying around, but just about anything will do.

• 2N7000 N-fet

• Which ever high power BJTs and FET you come across. But it's hand to keep at least one decent N-FET laying around.

• LM7805 and LM317s. These are almost indestructible. The 317's with a single resistor makes a really hand current source that's good when you want to protect an output or power supply but don't need anything to accurate. (The circuit is in the datasheet)

• Opamps - TL072 or TL074 for a general purpose, low input current. LM358 are easy to get and while not rail-to-rail, can be used for many applications of a single rail. I also have a sampling of different rail-to-rail op-amps that get used occasionally.

• Some shunt references. LM336, TL431 or many others. Adjustable ones are hand to keep on standby so you set them to the value you need.

• 1N4148's and 1N4007's.

• A couple of spare micro-controller in you favorite flavor.

• I'd downgrade the resistors - I'm quite happy with 1/4 Watt resistors. Also, I'd look at replacing the LM7805 with something more power efficient. 7805's will drain batteries all on their own :( – edebill Dec 12 '09 at 16:38
• Well... I guess I don't use batteries that much. – Clint Lawrence Dec 13 '09 at 4:26
• I'd agree that 1/2W is more than you need, but I'd advocate using the money you save by going to 1/4W to upgrade from E12 (10% tolerance) to at least E24 (5%). See bit.ly/cTVeGp for more options, like stocking the E48 (2%) set in 1%. To do the math for you, there are 12 values/decade in E12, 24 in E24, etc, for a total of 49 values in 100-1M for E12, 97 in E24, 195 in E48, etc. If you can find them at close to $.05 each, and you get 10 each, that gives you$24.50 for E12, $46.50 for E24, or$97.50 for E48. Probably easier to get a kit like:elexp.com/cmp_2501.htm . – Kevin Vermeer Jul 8 '10 at 1:19
• While I agree that better tolerance is useful, I've already collected too many "weird value resistors" that I'll probably never use. – davidcary Nov 13 '10 at 5:26

I feel like the component left off this list is the almighty zener (maybe some 1V and 5V so you can build up voltages you need). You can use them for grunt references for DACs (assuming you don't care about drift) and they are useful for setting up voltages wherever you need them. They also work great as clamps in the event you want to protect your circuit from overvoltage at one point or another (the zener will kick in and start sinking current whenever the node it is on goes above the voltage of the zener). You can also use them to set up current sources in conjuction with a resistor and a transistor to have a very stable current source for other parts of your circuits (works much better than just a resistor and a voltage source).

I never really realized the power of them until I started using them.

• I completely forgot Zener Diodes. I forgot Diodes all together, but they are used regularly. I love a zener, and 5.1V zener diodes are almost completely temperature independent. – Kortuk Dec 10 '09 at 19:18
• 1V "zeners" have a soft knee and generally lousy specs. So don't string them together, get the higher-voltage part. – markrages May 14 '11 at 18:06

I really enjoy having a few BJTs and a few MOSFETs around. If you are used to using them, building a very high gain amplifier with an offset to put it in the middle of your ADC range will always pay off. The number of times 1 cap, 2 resistors and a BJT replaced 4 op-amps with an entire range of components.

To make a list:

Resistors, the normal set you can get, I like to have 1 ohm through 10 Meg, but I have a lot of resistors, they never hurt.

Caps, the basic values, 1000pF, .1uF, 4.7uF, there are a few more, but you get the idea.

inductors, I honestly never have any, I only used them in projects specific to a professor assigning them(RFID).

BJTs, just get some cheap through hole ones, I would keep one that can handle pretty high current, and them some that are designed for the 100uA - 500mA range.

op-amps, there are many times where they help, comparator operation is my most common. I like rail-to-rail op-amps. There are many other things to look for, but for my use, rail-rail is the most important.

Some 5V and 3.3V linear regulators, it is nice to be able to step from a wall converter that is something around 9V to a usable range.

Heatsinks can be nice to have, especially for those linear regulators.

LEDs and Photodiodes, LEDs for debugging and so forth, photodiodes because you never know when you need to measure light(I like to have a few IR and some general visible light ones).

Flash, for example, this PDIP 1MB chip is a 1.34 a piece and can really improve the memory of your system. You can get a little larger for about the same if you do not mind a SOIC-16 package.

I know Flash memory seems a bit odd, but I have so many different projects where non-volatile memory helps, and often I just need more space, it meets both bills.

Hope this list helps.

• Thanks Kortuk. This certainly does help. Question on the caps: electrolytic or ceramic? On the BJTs, op-amps, regulators any specific part numbers I should look out for? – jdiaz Dec 10 '09 at 7:29
• @Kortuk: Can you explain what you mean by using a BJT over an op-amp in your first paragraph a little further? – Clint Lawrence Dec 10 '09 at 10:40
• @jadiaz, I think having both electrolytic and ceramic are important. I like to keep alot of ceramics around in the smaller values(1uF and less) and I like to have all of my big caps be electrolytic, as they are being used as a power supply for the chip, but are not good at absorbing high frequency power. @Clint, I will edit in an example a little later when I have a chance. – Kortuk Dec 10 '09 at 17:53
• Tough N (P if you get a good deal) MOSFETs make a good basic brute force switch for a lot of purposes from PWM switching to adjustable current sources. – XTL Jul 3 '10 at 22:56
• Agreed. I use P if they are a good deal, but in general use N, just due to the deal. – Kortuk Jul 5 '10 at 19:39

Don't forget test equipment!

Besides a good DMM (4 1/2 or 4 3/4 digits are worth it, also look for one that has capacitance sensing), get some patch cords. I highly recommend items from Pomona. We just made a recent purchase, mostly of patch cords (minigrabber on both ends, banana-to-banana, and banana-to-alligator), but also a few quirky things from them:

• # 6342 (probes with "pogo" tips) -- these are spring-loaded probe tips that add some compliance so when you are pressing onto a circuit board, it exerts a more controlled force.

• Is the set[1] good for a hobbiest/student? Have looked for the equipments you listed a long time. [1] elexp.com/ktc_lead.htm – hhh Jun 22 '10 at 5:57
• For pointy probes, I have used just 22AWG wire strapped with normal multimeter probes. Works well and needs just 1 set of probes. – hhh Jun 22 '10 at 6:50
• If I had to pick one, I would buy the #6342 pogo tips in a heartbeat. They weren't that expensive, and the springyness is invaluable for making good contact. You just can't do that with non-compliant wires or probes, without having to sit there and press hard against the component in question. – Jason S Jun 23 '10 at 23:47

I keep around breakaway pins and headers. They're great for dev boards, orders from SparkFun and for working with an Arduino.

I would also suggest some male-male jumper wires if you plan on using breadboards with an Arduino. They're very handy. Instead of jumper wires, I use solid-core hook-up wire in various colors (I believe 22-ga, but the size isn't critical). I find I have made quite a collection of varying-length jumpers this way and saved a few bucks, but having them soldered to pins prevents you from breaking off an overused wire in a header, which is quite frustrating. It's only a few bucks, so it's probably worth it.

Also, a box of those pre-cut and tinned breadboard jumper wires are really handy. They come in varying colors and lengths, which makes it easy to build prototypes quickly. I do keep a box of these around.

For small but versatile circuits, such as proven power regulators, those tiny breadboards can't be beat. I have a few around with common circuits that I frequently use as building blocks for larger composite circuits.

I know these aren't components, per se, but I find them very handy to have around to use with my components and felt it was within the spirit of the question to include them.

• 22ga is best for breadboarding. 20ga is too large, and 24ga you may find coming loose too easily. – Jason S Dec 10 '09 at 22:29
• Thanks for clarifying! It's one of those things I never committed to memory and only notice when on the spot like this. FWIW, I have successfully used 24-ga (In fact, I believe that's what the boxes of precut breadboard wires are) and haven't noticed any problems. – Lou Dec 11 '09 at 13:24

• TLVH431 -- I highly recommend this one, it's inexpensive and works up to 18V while using a 1.25V reference pin threshold (original TL431's are 2.5V) and reference pin current is very low. TLV431 is less expensive if you only need up to 6V operation.

Analog multiplexers:

• HC4051/4052/4053 series -- these are good for general-purpose, low-source-impedance (<1kohm) input voltages (leakage current spec is 1uA which is pretty lousy)

• FSA4157 / NLAS4157 -- these are good for micropower circuits, they specify leakage current much lower than the HC405x series.

dual opamps that are relatively inexpensive but decent (look at specs to see what you like): I prefer duals as they are more economical than singles but easier to layout than quads.

rail-to-rail input and output (RRIO):

• MCP6242
• MCP6022
• TS922

rail-to-rail output (RRO)

• MCP602
• MCP617
• LMV358
• LMV822
• LMV722
• LMV772
• TLC2272
• TLV2442
• LVC342
• TLV272
• I knew I would forget a few, Analog multiplexers are an example. I never have enough, having to order 20 or so every couple months. – Kortuk Dec 11 '09 at 1:12

Lots of 10K resistors.

• If I may ask, why? – J. Polfer Feb 2 '10 at 16:15
• Because you use them for everything. :) Pull-up resistors on digital chips, gain resistors on op-amps, etc. It's always the value we run out of first. – endolith Feb 5 '10 at 22:24
• -"If the only tool you have is a hammer, every problem looks like a nail...". Maybe some other components as well? – Johan May 14 '11 at 6:35

74HC595

I'm a bit old school - don't forget your 555 timers.

• ...or the 741 op-amps... – ttt Apr 1 '10 at 8:56
• forget the 741 op-amp! You can buy better opamps for less money. – markrages May 14 '11 at 18:04

If your working with Pics and Arduinos it's probably a good idea to get some shift registers, you never know when your going to need a load of extra ins and outs.

I would vote for having a 5K or 10K twenty turn pot on hand. It can be useful for things like nulling offsets tweaks during breadboarding. I doubt you'll be using the pots much in the final circuits however, so just a couple will probably do you.

• yeah, we have a general rule of no potentiometers in production circuits. – Jason S Dec 10 '09 at 22:28

Solder Wick

Lots of common components can be salvaged from almost anything with a PCB inside.
(I am not suggesting that you should ever rely on this though.)

And of course, solder wick really helps when you make mistakes too.

Don't forget those 10A fast-blow fuses for your DVM

=P

I'll say it: some microcontrollers of your choice.

AVR is extra simple to wire up and breadboard friendly, easy to program (free as in freedom tools and programming hardware you can make in a jiffy), has pretty nice GPIO system and many models have ADC's and PWM generators and decent documentation. They're also more easily available compared to many others. Some attiny2313 (no AD) and attiny26 (fast PWM, AD) are my choices. But don't count out another arch if you know it works!

Even if you'll want to do something differently eventually, an MCU can easily generate sequences, measure/capture things, switch things, do PWM or frequency generation, logic operations, interface to many devices (see also: Bus Pirate) and/or enable computer control, work as clocks or timers etc. And they are pretty reasonably priced.

Even if you don't want to use microcontrollers at all in a project, they'll be useful for prototyping and instrumentation.

and to above 22 gauge solid hook-up wire, various colors 3220 point QUALITY breadboard assorted relays

Sorry to resurrect this old thread, but it came up in the "Related" box and I felt like I needed to put my $0.02. Electronix Express is a great resource for cheap assortments of basic components. They're tailored towards the education and hobbyist industries, and have a basic group of slightly old-school components. For example: • 365 count (5 each of 73 standard 5% carbon film resistors from 1 ohm to 1 meg) 1/4W resistors for$6.95
• 220 count assortment of mylar, ceramic, monolithic, and electrolytic capacitors from 2.2pF to 1,000uF for $14.95 (Or$6.95 for a 90-pc kit)

Only complaints are no datasheets and a slightly difficult to navigate web store. However, it's fun to just browse. They also have tools, protoyping/breadboarding equipment, and project kits in addition to their components. I usually spend more than I needed to.

Note: I am not affiliated with them, just a satisfied customer.

• Cannot find international S&H. I have used Futurlec with its "Value Packs"[1] and S&H is transparent [2]. But have to try your tip: particularly the testing set[3] interests me. Again just a satisfied customer. [1] futurlec.com/ValuePacks.shtml [2]futurlec.com/Delivery.shtml [3] elexp.com/kit.htm – hhh Jun 22 '10 at 6:06
• Futurlec have improved their shipping times lately, my first orders took around a month, now they're down to around ten days. – user1307 Jun 25 '10 at 1:50
• Contacted Electronix Express. Minimum order is 100USD for international shippings, not for me as above 50USDs' pkgs tend to go to customs -- sad and true. – hhh Jun 25 '10 at 10:49

Decoders such as the 74LS138 for Address Decoding.

LCD's such as the basic 16x2 character LCD with the HD48770 controller, always nice to have a few of these for projects, they can also come in handy for debugging.

Definitely add relays to the list, and don't forget flyback protection diodes for the relay coils so you don't blow up your microcontroller outputs! Some rectifier diodes will work fine, and are good to have around for reverse voltage protection circuits too.

Make sure the relay coil voltage and current rating can be met by your microcontroller's outputs.

Very useful for safely driving lamps, solenoids, etc.

Flux, paste and their removal tools

When the pump and the solder wick are not enough...

I like cut in costs so actively looking substitutes on the first item. For the second items, I have been using items meant for car-industry: big bottles, cheap and long-lasting.

1. STANNOL® MINI-FLUXER (to manipulate the surface tension)
2. acetone or paint-removal-spray (to remove excess rosin)
3. rosin (like this) and ethanol (to make your own fluxes)