Electronics parts kit on a budget
Ugha
Posts: 543
I'm pretty much a newbie to electronics, but I'm working my
butt off to learn as much as I can, as fast as I can.
So I've decided to try pretty much any project I can think of
just to learn more.
To this end, I've decided to assemble as complete of a tool
and parts kit as possible on a very fixed income.
This is where I need your help...
I need to know what electronic parts you guys use the most
in your projects related to the BS2 and the BOE.
I've got a few 10+ year old general purpose ICs like 555s
and op-amps and such from some old radioshack electronics
kits, as well as everything that came with 3 boebot kits.
I've also got various transistors although I can't find
any info on them so I don't know their specs.
Same deal with some voltage regulators... and a few other
various parts from various locations.
Basicly... whats cheap, handy and easy to use?
butt off to learn as much as I can, as fast as I can.
So I've decided to try pretty much any project I can think of
just to learn more.
To this end, I've decided to assemble as complete of a tool
and parts kit as possible on a very fixed income.
This is where I need your help...
I need to know what electronic parts you guys use the most
in your projects related to the BS2 and the BOE.
I've got a few 10+ year old general purpose ICs like 555s
and op-amps and such from some old radioshack electronics
kits, as well as everything that came with 3 boebot kits.
I've also got various transistors although I can't find
any info on them so I don't know their specs.
Same deal with some voltage regulators... and a few other
various parts from various locations.
Basicly... whats cheap, handy and easy to use?
Comments
Unfortunately, this is a very general question with all sorts of different answers. So much depends on what you want to do eventually.
For examples of things to do with a BS2, you could go through all the Stamps in Class tutorials and make a list of the parts that the various experiments need, skipping those that have no interest currently for you. The old ICs are probably still good. The op-amps and 555s, although not the "latest" parts are perfectly good for learning and for use in some applications. The newer parts will work with lower power supply voltages and take less power, but you don't always need that. You can probably make your own transistor tester to check whether the transistors are PNP or NPN and check their gain (do a web search for hobby articles on transistor testers). For the voltage regulators ... look for the part number on them. Older ones are probably LM78xx series.
What's cheap and handy is what you already have or what someone else doesn't want. "Easy to use" depends on what you know or are willing to learn and how much work you're willing to put in.
····10, 22, 47, 68, 100, 220, 470, 680, 1K, 2.2K, 4.7K, 6.8K, 10K, 22K, 47K, 68K, 100K, 220K, 470K, 680K, 1M
Get 1/4W carbon film resistors: the 1/8-watters don't fit snugly in solderless breadbaords. Intermediate values can be filled in on an as-needed basis. The best bang for your buck from DigiKey comes at the 200-piece level. That may sound like a lot, but at less than 2 cents apiece, it really isn't. (If you happen to get resistors on tape, cut them off the tape; don't pull them out. Otherwise you'll have no end of trouble from the residual adhesive that sticks to the ends of the leads.)
As to caps, a grab bag of ceramics ranging from 100pF to 0.1uF should hold you there, along with an extra handful of 0.1uFs. To that, add a few 10uF tantalums and some high-value aluminum electrolytics, and you should be set.
You might also consider adding a couple rail-to-rail CMOS op amps (e.g. LMC6482) to the mix. (The more ubiquitous LM358 is not rail-to-rail, and its shortcomings can bite you at the most inconvenient times.)
A good 5V power supply is always handy and can be as simple as a regulated wall wart, such as this one from DigiKey. For use with a solderless breadboard, just cut the plug off, label the positive lead with some red shrink tubing, and tin the leads.
Finally, get some good jumper wires for your solderless breadboard. The ones Parallax is currently shipping (solid wire) are excellent. If you have the older ones with tinned, stranded leads, pitch 'em out once they lose their stiffness and buy some new ones. Also, save your resistor wire clippings. They're great for use as short jumpers.
-Phil
be used to emulate others so they are more useful, but I don't know which).... I've seen the 2n2222 (or something like
that) transistor mentioned more times than I can count... is there a reason why its better?
Stuff like that... In addition to stuff like... is it handy to always have a ADC on hand or can you emulate it with
other components?
Basicly... what are the most used general purpose ICs and components?
On a side note... I appreciate the info on the stuff you mentioned in your reply Mike... would it be acceptable
forum etiquette for me to ask about identifying specific components? For example... things that look like transistors
but don't work in my transistor tester (I figured out how to test them a little while ago, I should have came to
you guys first).
That's only after my part number searches fail of course.
For your other questions ... it depends.
Sometimes you can emulate an ADC with just a couple of resistors and capacitors. The values depend on the voltages involved and the speed you need. This website discusses using this sort of thing to monitor battery voltage: www.emesystems.com.
There are several cheap, readily available switching transistors. The 2N2222A is widely available and cheap. On the other hand, there are others like the 2N3904 which is also available in a PNP complementary form, the 2N3906. These are also widely available and cheap. They vary slightly in terms of gain and voltage ratings.
Logic gates ... that depends on what sort of circuit you're making. Part of using a Stamp or other microcontroller is to have the microcontroller do the logic.
Phil made some very good suggestions. Start there and with what you have and learn about using the Stamp. Go through the existing Stamp tutorials and buy other parts as you need them. You'll soon have a much better idea of what you're interested in and what you need to support your uses.
Since there are hundreds, perhaps thousands of different transistors, and each one has certain advantages in certain situations, it might be somewhat to put together a general-purpose kit. The choice would be very dependent on what sort of projects you have in mind. Relay drivers, for instance, would be different than instrument sense amplifiers.
It would seem to me that one good way to choose might be to keep a list, made from schematics of projects that you are interested in. Bear in mind that a LOT of transistors are close enough to others to allow substitution.
The above comments apply to ICs as well, but not to such a large extent. There are some basic circuits that are frequently used. 555 timers are popular with a lot of experimenters, for instance.
Hopefully, a lot of people will weigh in on this one, 'cause the more opinions the better...
Regards,
Terry
--- There is ALWAYS more than one way to skin a cat!
Anything else you guys might have to add would be greatly appreciated.
And doubly thanks to you Phil... this is just what the kind of thing I was hoping for.
One question though... what's rail-to-rail? Excuse my newbieness.
Does anyone have any other warnings about various components? Ones known to break down? Ones known
to be overly complex compared to their peers? Overpriced or underpowered ICs? Anything to help guide
me down the path.
Terry: What other ICs are commonly used for experimentation on various projects?
Phil: That's a good idea about the resistor clippings... I've also found that soldering them to stranded wires
are a good way to connect them to a breadboard.
Side note/stray thought:
Considering how amazingly cheap a lot of electronic components are... why are electronics so darned expensive?
So onesy-twosy "prototype" quantities can be a bit pricey.
I mean... why can I assemble an LED keychain light for less than $1, yet if I go to the store it costs $10?
Your point kind of even reinforces my question.
Oh, and part of the problem is the cost of a flash-light quality LED. They're considerably more than $1 each.
Anyways... back on topic:
What about relays? Are some better than others? (not including their volt and amp limits of course).
I'm especially curious about ICs... if anyone has any suggestions.
"Rail-to-rail" is a term applied to both inputs and outputs of an op-amp. When applied to inputs, it means that the amplifier will accept any voltage between Vdd and Vss (the supply "rails") on both inputs, and differentially amplify them in the expected fashion. (The LM358 only knows what to do with input voltages up to Vdd - 1.5V.) When applied to the output, the term implies that the output voltage can swing through the entire Vss to Vdd range, although in practice with a nominal load, it may be shy of that by several tens of millivolts. (The LM358 output range is Vss + 20mV to Vdd - 1.5V.)
In many cases where a circuit contains both analog and digital devices running from a common supply (not always a good idea, BTW), it's handy that the analog devices be able to accept the full digital voltage range which, in the case of CMOS logic, includes Vss and Vdd. A simple example of this is the PWMOUT output from a BASIC Stamp. After filtering, the voltage can range all the way up to 5V. To handle this with an LM358, you'd have to either divide the filtered voltage down, or provide the op amp a higher supply voltage. Neither of these options is terribly onerous, and people have been using the '358 for years; but the newer rail-to-rail amps do make life easier, and they're not expensive.
-Phil
Having said that, the Analog And Digital Interfacing kit from Parallax is excellent for general purpose transistor interfacing. It has exactly what you need to do the class, no double-guessing anything.
One thing comes to mind when thinking in terms of logic; many different logic devices can be improvised from ICs that contain multiple inverters. Also keep in mind that positive logic and negative logic are arbitrary to some extent. I positive logic AND gate (if I recall correctly) can be viewed as a negative logic OR gate, so if you have one or the other, and an inverter or two, than you have both...
A trick to acquire cheap parts, if you have access to old circuit boards, is to salvage the parts. The leads tend to be short, but the price is usually right! I know people that used a hair-dryer to heat solder pads en masse, than gave the board a sharp rap and watched the parts fall out...Some parts can be damaged that way, but still...
I recall starting a collection of TTL ICs, then watched the world move on to CMOS.
By the way, I find that the cost of purchasing parts is usually less annoying than the freight bill. I am within driving distance of two large distributors, and they both discourage walk-ins.
As for relays, cost is also driven by number of contacts, complexity of contacts (NO, NC, equivalent to DPDT?), the type contacts, the type of metal that the leaves are made of, etc.
You always want to choose something that will work, and hopefully work for the design life of the object, but cost as little as possible while meeting all of the criteria.
As for cost of the finished products vs. buld-it-yourself, of course there are middlemen, shippers distributors, retailers, etc.
And now I'm getting waaaay off topic for the basic stamp forum <grin>
Regards,
Terry
A few questions...
Forrest mentioned 74HC595 and 75HC165 for increasing I/O pins... I assume these are multiplex and demultiplex chips?
I know next to nothing about the process... but is anything besides these two chips required?
What about communication protocols for ICs... I've seen some that are TTL, I2C and some that are a bunch of other
letters which make no sense to me [noparse];)[/noparse] Which protocol is considered "best"? And better question... which protocols can
the BS2 support?
Side note: Someone who actually knows what they are doing (IE: someone other than me) should take all this great
information and make a parts guide for newbies getting into experimenting with electronics. A parallax PDF would
be a great help to a lot of people.
The Basic Stamp is well documented - suggest you also read What's a Microcontroller here
www.parallax.com/Portals/0/Downloads/docs/books/edu/Wamv2_2.pdf
and the Basic Stamp Reference Maual here www.parallax.com/Portals/0/Downloads/docs/prod/stamps/web-BSM-v2.2.pdf
··· I've basicly done what Phil suggested with the different components as far as types and values, those are great starting values/parts..· I often grab up electronics that people are·about to throw away and scrap them out.. Radio Shack has a desoldering iron that works great. Just remember to get some extra tips..·Solder suckers, braided copper wire, and all the others, I've had no luck with at all. A regular soldering iron can sometimes be used on Caps and transistors because the leads are close, you can heat them all at once. IC's are a different story, you need a desoldering iron to get them, otherwise your wasting your time..· Some good, small flush cut·wire cutters, small pair of needle nose pliers, and a small file ( like what you use to clean points in a old distributor from a engine ). With those you can clean up the left over solder on the leads·( filing, slow going, but hey it's free stuff ), straighten leads etc. Just make sure you test them before you "clean" them up. Over the yrs I've collected all kinds of goodies, I've got bags and bags of stuff. TIP120's, FET's, 555timers, Opamps, heatsinks, mica insulators, you name it. Many of my projects are mostly from used parts..·· Takes time, but I think it's worth it. Once you do it for a while you learn whats easy to salvage, and what you have a need for.. If you cant identify it then leave it, if it takes longer than a certain amount of time to extract it·then it's not worth it etc...·· I find it also helps if I try to identify the parts, such as resistors in such a way that you'll remember what the colors and numbers mean, makes it faster when sorting through parts trying to find something you need for a project.. I organize my parts, but the odd ball stuff just gets tossed in a bag..· As many hobbies as I have, one of my favorites is electronics because it's so much cheaper than my other hobbies, and thats mostly because I salvage parts that 95% of the people dont have a clue about so most of the time the "junk" is free..
· For jumper wires, I use solid copper phone cable.. Buy it by the roll.. You need a wire stripper that will go that small though, I cant remember what gauge it is off the top of my head though..· I like keeping my breadboard organized, so leads that are cut exact, also bending jumpers to make it nice and neat. Drives me nuts having a 2'' wire looped over the board when the connections are 1/4 inch apart. The phone wire being so cheap, you dont have to worry about reusing them after your done, although I do if I can.. Just dont reuse them to many times, being solid copper after it's been bent a few times they can break off in the breadboard. You can take my boards apart, so thats no big deal, but some boards you cant, you might end up with a short later on in the board if you cant get the broken peice out..
· I never have tried using a hair drier ( heat gun would work better ) before, if I remember I'll give that a try tomorrow and post back my results.. That would be a HUGE time saver. I've got a bunch of boards with parts I want, but the way they are soldered it's difficult to extract them ( flush cut at the board )..
·· You can also find great deals on bulk parts, not to long ago I bought 2000 LEDs for 30 bucks. One place has 5LBS of assorted·resistors for 5 dollars.. "Grab bags" of different things, some places even sell used boards with a bunch of parts you can take off for cheap.. http://www.alltronics.com
· One thing I dont skimp out on are multimeters, they are a must have. I've used cheaper meters in the past and never liked them. But for just starting out cheap one is fine, just look for a auto ranging meter that can read resistance. Getting several different kinds of test leads is important.. I've been debating on getting a benchtop meter lately.. The meter I use all the time is a 500 dollar meter I use for work and automotive apps, I just hate carrying it around with me everywhere I go, so much stuff on it there are a few things I have no clue how to use LOL.. So a bench meter, and a scope are next on my list. You may not have a need for a scope for a long time, I dont have a huge need for one, but it's would be nice to help my understanding of signals..
What about LCDs? Or LCD controllers? What do you guys keep on hand for those?
What about CMOS chips? Do you guys find that the static sensativity makes them unsuited for projects
and you have to buy non-CMOS (I think they are called TTL) versions of something you have already?
What about H-bridges and controllers? What kinds do you usually keep on hand?
How about hardware? Milling your own stuff is extremely expensive... where do you get the
frames for your robots/projects?
Identifying parts you salvaged from an old pcb or you find laying around is usually not so difficult anymore. There are several websites offering data sheet information for 99% of the electronic parts you will most likely encounter. And best of all - they are free (ok, some are limited to 50 searches per day....).
My favorites are:
http://www.datasheetarchive.com/
http://www.datasheetcatalog.com/
http://www.datasheet4u.com/
I also have a collection of data books that list all transistors (manufactured at the time of print), or Op Amps or ICs, but I find I hardly use them anymore. It's so easy to do a quick search in one of the sites...
For Integrated Circuits: Locate the (or one of the) manufacturers and try their website for "Application Note"s on the chip. Sometimes they have more info on how the chip may be used. Very helpful at times.
Enjoy your hobby!