Pages: [1] 2   Go Down
Author Topic: Beginner question: building a parts "library"  (Read 3246 times)
0 Members and 1 Guest are viewing this topic.
Toronto
Offline Offline
Jr. Member
**
Karma: 0
Posts: 70
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

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.

Thanks!
Logged

Forum Administrator
Cambridge, MA
Offline Offline
Faraday Member
*****
Karma: 12
Posts: 3538
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

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.  
Logged

Copenhagen / Denmark
Offline Offline
Edison Member
*
Karma: 6
Posts: 2360
Do it !
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

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.

Logged

Hollywood, CA
Offline Offline
Jr. Member
**
Karma: 0
Posts: 66
Actor / Engineer
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

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.
Logged

Jon McPhalen
Hollywood, CA

berlin
Offline Offline
Sr. Member
****
Karma: 0
Posts: 295
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
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 starte to explore the octopart.com option.

here's a quick public partslist:
http://octopart.com/partlist/view?id=NjEzNzMy

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.


i


« Last Edit: December 18, 2007, 10:36:20 am by leKuk » Logged

Forum Administrator
Cambridge, MA
Offline Offline
Faraday Member
*****
Karma: 12
Posts: 3538
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Awesome.  I added a link to it on the playground: http://www.arduino.cc/playground/Main/Resources.  I hope people will continue to build on it.
Logged

0
Offline Offline
Jr. Member
**
Karma: 0
Posts: 70
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

[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?

thanks
Logged

0
Offline Offline
Faraday Member
**
Karma: 8
Posts: 2526
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

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.

-j

Logged

Hollywood, CA
Offline Offline
Jr. Member
**
Karma: 0
Posts: 66
Actor / Engineer
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

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.
Logged

Jon McPhalen
Hollywood, CA

0
Offline Offline
Jr. Member
**
Karma: 0
Posts: 70
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

ah aright, that's a good point. I've never thought about it  :smiley

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?

cheers
Logged

berlin
Offline Offline
Sr. Member
****
Karma: 0
Posts: 295
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
Awesome.  I added a link to it on the playground: http://www.arduino.cc/playground/Main/Resources.  I hope people will continue to build on it.
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?

 

« Last Edit: December 18, 2007, 01:24:16 pm by leKuk » Logged

Toronto
Offline Offline
Jr. Member
**
Karma: 0
Posts: 70
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

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!).
Logged

Greenwood, Indiana
Offline Offline
God Member
*****
Karma: 0
Posts: 508
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

kek, not perfect but it does find 1/4watt through hole resistors.

http://octopart.com/search?q=1%2F4+watt&c=10&d=0

At least resistors are not likely to quit being through hole for some time.


Logged

If it was designed by man it can be repaired by man.

Toronto
Offline Offline
Jr. Member
**
Karma: 0
Posts: 70
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

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.

http://www.upwardnotnorthward.com/2008/01/electronics-shopping-list-part-ii.html
Logged

Brisbane, Australia
Offline Offline
God Member
*****
Karma: 1
Posts: 593
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
would it be technically possible to allow the javascript embed of partlists in this YaBB installation?
I could steal everyone's account with a tiny snippet of javascript. See why it isnt allowed? smiley-wink

It would be possible to make a BBCode for the site though.
Logged

Pages: [1] 2   Go Up
Jump to: