I recently purchased one of adafruit's "Arduino Starter Packs" and have been having a lot of fun with it; easy to use, powerful, so congratulations and thanks to everyone involved in making it.
My background is mainly in programming, so that side of things is easy to me; the electronics side of things I haven't done since high school, and even back then what I did was pretty rudimentary, so I'm still getting up to speed (and, as an aside, I'd certainly appreciate any suggestions on where to go/what to do to learn more about that side of things).
Components aren't like code libraries, and I've found that a major limiting factor in playing around with my new setup is that I really don't have very many electronic components, other than the few things that came in my kit and some components I've managed to scavenge from old electronics around the house. What I would like to do is assemble for myself a small (and preferably inexpensive) library of parts that give me a good basis for experimenting. I'm wondering if there are suggestions about what I should get, and maybe even if there are places that offer component "grab-bags" to begin with.
Some things seem obvious to me, like a good selection of resistors and capacitors (although I don't really know what values I should look at). When it comes to things like diodes and transistors, I really don't know what I'm looking for. I've come across a few specific ICs I'd like to play around with, like bit-shifters and BCD to Seven Segment, but I'm a little lost there.
Any suggestions on what I should get, and what the best/most economical way to get it is? As for where to get it, in a few days I'll be in Toronto, Canada for the holidays, where I know of several great stores to get components. The rest of the time I'm stuck with ordering online, but between superstores like Digikey and Jameco and specialists like Sparkfun and Adafruit, I'm confident I can find whatever I need.
I don't have any specific recommendations, just some suggestions for people who might.
One great way to collect this information (besides answers here or a page on the playground) might be a parts list on Octopart, which would allow people to buy the parts from a variety of distributors.
I would not recommend grab bags. Sometimes they contain good stuff, but mostly you end up with lot's of components that are either not veru usable values, or components that are very difficult to identify.
Some electronics shops have resistor and capacitor assortments with the most commonly used values.
I often recommend stocking the following five resistor values:
220
470
1K
4.7K
10K
The 220s are used for series pin protection; the 470s for LEDs when you're only going to light a few; the 1Ks for LEDs when you have a whole bunch and need to limit the overall current; the 4.7Ks are used for I2C and 1-Wire pull-ups, and the 10Ks for standard button/switch pull-ups/pull-downs. I actually have a five-compartment plastic case that I keep these in.
One great way to collect this information (besides answers here or a page on the playground) might be a parts list on Octopart, which would allow people to buy the parts from a variety of distributors.
it seems you can't search for partlists on octopart. could someone of you try if it's possible to add items to that list and save it under a new name?
plus: i didn't add resistors just because i couldn't find any 1/4W through holes in that billion of SMT parts. how do you search for them?
as for manufacturers/models: i chose those parts first in the search result that had a pdf datasheet attached.
maybe we should discuss individual parts and do seperate lists for special ICs/caps/Leds etc. That way i would be easier to explain them in the partlist description (individual parts can't be commented i think).
//kuk
PS: it seems the octopart list can also be embedded in webpages using one line javascript. unfortunately YaBB doesn't like this
EDIT: individual parts can be commented. it also seems that anyone can create a personal copy of list and edit/publish it under his/her own name!
so if you know of components that are essential, somehow "general purpose" please put it in this thread with a short description and i put them on the list.
[edit] the 1Ks for LEDs when you have a whole bunch and need to limit the overall current[/edit]
hmmm, i'm not sure i understand this. I'm planning to use around 48 leds using 6 4051s. At the moment I've got only six connected with 220 Ohms resistors. I found this values by using the formula:
R = (Vs -Vl) / I
where
VS = supply voltage
VL = LED voltage (usually 2V, but 4V for blue and white LEDs)
I = LED current (e.g. 20mA), this must be less than the maximum permitted
Do I need to change the resistors if I add more Leds?
You have to think about maximum current consumption of the component or circuit. If you've got 20mA per LED, and there are 100 LEDs in your circuit, that 2000mA (2A) max current draw is way over the 500mA max that USB can provide, for instance. Your driver IC will likely have a maximum output (for the whole device, in addition to the per pin limit) as well.
What you have to do is look at what your device is capable of driving -- and my values are based, generically, on LEDs being driven right out of a microcontroller, and tend to be somewhat conservative.
Looking at the ATMega168 data sheet it says that a pin can sink or source 40 mA, with a total on all pins of 200 mA (this is the limit through the Vcc and GND pins). So, when calculating your resistors you need to take both values into account when using a direct connection. If you're going to run the LEDs through another device (e.g., ULN2803) then you more latitude with the number of LEDs and the brightness you can achieve.
ah aright, that's a good point. I've never thought about it :
what's the solution to this problem?
However, I assume that by using 48 leds in 6 analogue multiplexers (401), theoretically only 6 leds can be on at exactly the same time. Thus, it'll only need a maximum of 6*20 = 120mA.
Am I missing something?
would it be technically possible to allow the javascript embed of partlists in this YaBB installation?
how about flash from trusted servers (youtube) or is it disabled for the same [security?] reasons?
Thanks for the information! The resistor values are particularly helpful, I'll be sure to pick those up. The Octopart list also looks like a great idea, I'll definitely be using that in the future (and I hope it keeps growing!).
I don't know if anyone's interested, but, after having been at this for a few weeks now and gotten my bearings a bit, I wrote a (very long-winded) blog post on buying parts. I tried to stay away from explaining how to use thing, and focus on what you might want to get and why. Hopefully someone who is in the same position I was a few weeks ago might find it useful.
I've brought some kits from maplin before now. You can get an E12 series resistor kit, which gives you all the resistors in the E12 range, which for this sort of stuff would be all the resistors commonly used. You can also get a GCSE component pack and case, which comes with an assortment of stuff, including some resistors, capacitors, transistors, LED's (i think) and a few vairous other componenst such as 555's. www.maplin.co.uk
I've brought some kits from maplin before now. You can get an E12 series resistor kit, which gives you all the resistors in the E12 range, which for this sort of stuff would be all the resistors commonly used. You can also get a GCSE component pack and case, which comes with an assortment of stuff, including some resistors, capacitors, transistors, LED's (i think) and a few vairous other componenst such as 555's. www.maplin.co.uk
Maplin are a little pricy. I got [u]these[/u] off ebay. They are 1% metal film rather than maplin's 5% carbon E12 kit, and you get over four times as many. Costs 1£ more shipped, but its from Hong Kong so took a week. Great deal tho if you are likely to need a bunch of resistors
yeah, id agree maplin is a little bit pricey, but may well be more available to some people cus of their stores, also, i tend to find their products are a bit more geared to education.
I really like the idea of creating an Octopart parts list containing most of the common parts used in Arduino projects. I checked out the list made by Kuk but I couldn't find a way to add to it. What I did was create another parts list that includes all of the parts used for the projects in "Making Things Talk" by Tom Igoe. I made the list in such a way that all of the parts can be purchased at once from Digikey (so that someone doesn't have to purchase the parts from several vendors just to get started). Most of the parts have a datasheet associated with them as well.
Octopart doesn't seem to have a way to collaborate on a parts list so maybe Kuk can add the relevant items from my list to the official one?
The list includes 1/4W Resistors at 100, 220, 470, 1k, 10k, 22k, 100k and 1M; Caps at .1uF, 1uF, 10uF and 100uF; 3.3V and 5V TO-220 regulators, Red and Green LEDS, a 2n2222, 1n4004 and a zener diode, TIP120 in a TO-220, reset switches, male header pins and a 9V battery clip. It doesn't include a breadboard, wire or pots (I haven't found a good bread-board mountable pot I like at Digikey yet - I really like the Bourns 3386T-1-104). I began commenting the parts, but I haven't finished that yet.
Perhaps an admin can setup a wiki page for various part lists, and where to get the parts.
I am also confused as to what I should have to begin experimenting!
