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Offline CompChemEngTopic starter

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What parts should a beginner buy?
« on: July 04, 2011, 07:06:01 PM »
Hey all,

I'm just starting.  I've got little free time on my hands, no significant electrical experience, and need to get moving quickly.  I'd like a good collection of standard parts so that, when I sit down to try to build something, I can just build it without burning time on trying to find something or having to order it.

This said, I'm in the Engineering field already (Chemical Engineering Ph.D. student), I've got no issues dumping a thousand dollars (or more if necessary) on parts if I get the chance to use the stuff, and I'm very comfortable with creating computer programs.

I've already ordered the Axon II + RoboRealm.  What else should I buy?

Incase it depends on what I want to build, whatever will introduce me to the field and help me learn it.  I'll worry about buying for practical concerns once I have some idea of what I'm doing.  =P

However, if I could get something that'd transmit data signals to a PC (and have some means of the PC recording that data), that'd be awesome.  My big thought here is that I've got a lot of lab instruments (even simple stuff like current meters and scales) which I'd like to have data from recorded automatically.  But, again, anything that will help me maximize my learning will be awesome.

Thanks!

Offline corrado33

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Re: What parts should a beginner buy?
« Reply #1 on: July 04, 2011, 07:16:39 PM »
I buy a lot of stuff from surplus sites that have "bundles".  They'll have a "bundle" of a hundred LEDs, or a "bundle" of various capacitors.  Sure, you may not get what you need, but if you NEEDED something you would have specifically ordered it.  I think if you stay with the hobby long enough you'll just collect things, or when you get good enough you'll be able to order everything for a project in one go.  

I don't know if it's the cheapest but electronic goldmine has a ton of bundles like that.  http://www.goldmine-elec.com/ Just look under "assortments".  

Sending data to a computer is easy.  Almost any micro controller can do it and I'm sure it can be done with other electronics as well.  Look up the UART/USART tutorial on this site if you want to know how.  You'll (most likely) need a level adapter though if you choose to go serial(they're like five bucks).  I'm sure there are other ways to do it though.  I have no experience with USB and MCUs.  

Anyway, this site has a great section of "where to buy stuff" here --> http://www.societyofrobots.com/robot_parts_list.shtml.

Oh, also, if you've never done anything like this, the $50 robot project is a great, simple way to start.  It's on the home page, you can't miss it. 
« Last Edit: July 04, 2011, 07:20:14 PM by corrado33 »

Offline garrettg84

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Re: What parts should a beginner buy?
« Reply #2 on: July 04, 2011, 07:58:23 PM »
I've purchased quite a few bundles of random parts off of ebay. I second the notion on goldmine-elec.com. I recently bought some stuff from a place that looks a bit shady, but the transaction was smooth and I got my parts pretty quick. http://iteadstudio.com/store/ is the recent place I purchased from. I also regularly pick up parts off of digikey and mouser.

Where you going to school at?
-garrett

Offline Webbot

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Re: What parts should a beginner buy?
« Reply #3 on: July 05, 2011, 01:02:18 PM »
Bundles tend to include stuff like resistors, capacitors, transistors, leds etc and sometimes the odd logic IC chips - but are a good and cheap way to build a spares bin.

If you aren't building a specific project to do a given task but you want to experiment with various things instead then I'd recommend that you get a decent breadboard (like a 'plug and play pcb!') so you can re-use stuff without any soldering/de-soldering.

Equally I would have some 'sacrificial components/devices' to use with the breadboard. This includes your 'bundle' but also a couple of cheap servos, cheap distance servos (like Sharp, or ultrasound like SRF-0f or Ping, some cheap motors, and some cheap motor driver ID like the L293D or SN755410. These are sacrificial in that you use them when experimenting via your breadboard but then buy the bigger and more expensive versions when you are ready to commit to a complete project which needs more powerful and expensive versions. Constantly plugging/un-plugging stuff in the breadboard can bend pins, blow stuff up if badly connected etc etc. So do that with the cheap stuff. Also some pre-crimped male/female connector cables (Pololou do a good range) are great for breadboarding.

You may want to 'build from scratch' in which case some ATMega328P chips with 32k of space that can plug into your breadboard are handy and cheap (few bucks). Better to blow them up rather than an Axon etc at say $100 a pop.

A TTL-to-RS232 convertor is a 'must have' as this allows you to connect your microcontroller (working at say 5v) to your  PC port (working at +- 12v levels). But make sure your PC has an old world RS232 port (normally a 9 pin socket). If your PC only has USB ports then look at a TTL-to-USB convertor or consider going 'wireless' with a bluetooth tranmitter from your robot and a bluetooth USB dongle at your PC end. Establishing comms back to your PC is imperative as this is the way to debug your programs.

If you are going to build a working robot then at some stage you will need a good soldering iron, wire crimpers, maybe a PCB etching kit (or expensive reflow oven for SMD components) and this is where the $ start to kick in.

Sounds like you already got volt/current meters etc. I have an old fashioned oscilloscope and, to be honest, I hardly ever use it. A modern digital o'scope may be of use but be prepared to pay a lot for a decent one. Alternatively: look at the SoR scope project which endeavours to use a microcontroller as the 'scope sensor' and uses your PC as the scope output. Fine for regular stuff but cannot for example interpret an I2C communication protocol. Not sure if that makes sense to you or not - depends on your knowledge on this stuff.

However: (and here is the sales pitch for 'free stuff'!). Think whether you want to concentrate on the low level stuff (like how to make the servos/motors move and how to read every sensors etc) and/or the higher level stuff such as the Artificial Intelligence 'brain' of your project.
If you are interested in the brain then my free WebbotLib can do all the low level stuff for you letting you concentrate on the higher level stuff. Since source code is provided then you can also use it as a reference as to how to do the low level stuff yourself.


Rambling answer: sorry. But it does depend on the sort of stuff you are interested in ie: maze solvers, line followers, autonomous roving vehicles, autonomous flying/swimming gizmos, a 'bring me a beer robot', vision, robot arms, a humaoid etc etc.


Webbot Home: http://webbot.org.uk/
WebbotLib online docs: http://webbot.org.uk/WebbotLibDocs
If your in the neighbourhood: http://www.hovinghamspa.co.uk

Offline corrado33

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Re: What parts should a beginner buy?
« Reply #4 on: July 05, 2011, 02:18:17 PM »
I agree with Webbot.  A breadboard is a MUST!!!  Spend 20 bucks and buy a decent one.  You'll run out of room quickly!  Mine even has banana jacks up top to connect power to.  Since you probably already have a bench power supply, this will be really nice.

I bought my level converter (TTL-to-RS232) at alldav.com for 5 bucks.  It hasn't failed me yet.  I'm SURE you could build one if you REALLY wanted to.  It's just a chip, some resistors, and a DB9 connector. 

Yeah I wish I had bought jumper wires from pololou.  They just have a single header pin on each side kinda and plug in and out of the breadboard nice and easy.  I just made a bunch of different lengths of wire and  stripped the ends off.  lol  Took me forever.

Offline Soeren

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Re: What parts should a beginner buy?
« Reply #5 on: July 06, 2011, 03:22:07 PM »
Hi,

However, if I could get something that'd transmit data signals to a PC (and have some means of the PC recording that data), that'd be awesome. 
You can get fairly cheap RF modules where the transmitter is smaller than a postage stamp.


My big thought here is that I've got a lot of lab instruments (even simple stuff like current meters and scales) which I'd like to have data from recorded automatically.  But, again, anything that will help me maximize my learning will be awesome.
You could use on-board data logging to a micro-SD card (or a USB key with more complex programming). Not real time, but good for running statistics on whatever you samples cover.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline CompChemEngTopic starter

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Re: What parts should a beginner buy?
« Reply #6 on: July 12, 2011, 02:53:37 PM »
Thanks all!  I'll be going through and making some of these purchases soon.

For the moment I'm trying to get a battery together.  I've read through SoR's guidelines (see also: Axon II Datasheet) (6V to ~7.2V, 6V preferred; at least 1000mAh; Hitec connector; Ni-MH or Li-ion) and I've been looking through the user-recommended shop on SoR's battery's list, All-Battery.

I'm a bit unsure of the details of:
  • how to buy a charger which will work with the battery that I buy;
  • if a pack of batteries bundled together would need to be unbundled before charging.

Would anyone be able to recommend a specific battery/charger set that I could buy from All-Battery?  Even if there are more factors for me to consider (i.e. price), it'll at least help show me a combination that could work.  As for price, I'm willing to pay whatever it costs for a decent set.

Thanks!

Offline corrado33

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Re: What parts should a beginner buy?
« Reply #7 on: July 12, 2011, 03:24:33 PM »
Battery packs don't need to be taken apart to be charged.

Since you have a decently large budget, but a nice charger.  A nice charger will be able to charge all types of batteries (Li-Po, NiCd, NiMH, lead acid) and at all different capacities.  I personally have a triton2, although there are many out there.  Lots of them run on 12V though so you'll either need a car battery or a 12V power source.  I used a modified computer PSU.

Offline CompChemEngTopic starter

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Re: What parts should a beginner buy?
« Reply #8 on: July 12, 2011, 04:12:03 PM »
corrado33,

So if I buy a Triton 2, it'll charge anything (that would be practical for a not-huge robot)?  Does it need something else like an Octopus RC Charging Cable to go with it?

I just need to make sure that I order everything, or when I get the parts in I'll then realize that I don't actually have everything and need to wait for shipping again.  =P

Thanks!

PS - Is "Triton2 EQ AC/DC Charger" the ticket?  Here's the full list.
« Last Edit: July 12, 2011, 04:16:32 PM by CompChemEng »

Offline corrado33

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Re: What parts should a beginner buy?
« Reply #9 on: July 12, 2011, 05:10:56 PM »
Hm, that charging cable is pretty cool!  But, you could always make it yourself for a dollar or two.   ;)  Besides, if you're going to build a robot and make your own circuit board (eventually), you can put whatever connector you want on it to charge the batteries.  But yes, with that cord you could probably charge most common battery packs with plug type connectors. 

I actually don't have the triton 2 you linked, I have this one.
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMAJ0&P=6

But the one you linked can be plugged into the wall.  When I researched chargers mine fit my needs perfectly, however your needs may be different.  Do a bit of research before you buy to find out which one will work better for you.  I mainly bought my triton 2 because I wanted to be able to charge 24V worth of NiMH cells.  That's 20 cells (aka individual AA rechargeable batteries). 

You can even make a charger if you wanted too.  If you just had one battery pack and wanted to charge ONLY that, you could probably find schematics online to do it. 

Offline CompChemEngTopic starter

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Re: What parts should a beginner buy?
« Reply #10 on: July 13, 2011, 01:36:01 PM »
I took corrado33's suggestion and went to http://www.goldmine-elec.com/ to check for some deals to start building a collection of robot parts to have around.  I found some stuff, but some of the deals seem too good to be true and I'd like to ask someone with some experience if the parts that I'm looking at could actually be useful to have around.  (Sorry about the English - lacking sleep.)

Could these motors be useful?  At less than 1USD/motor, it seems like a good deal, but I'd like to make sure that there's not something that I'm missing as a newbie:
http://www.goldmine-elec-products.com/prodinfo.asp?number=G17376B

Ditto for these LEDs?
http://www.goldmine-elec-products.com/prodinfo.asp?number=G17636

I'm mostly interested in the motors, though, incase anyone's time is short.  =P

Thanks guys!

Offline corrado33

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Re: What parts should a beginner buy?
« Reply #11 on: July 13, 2011, 02:38:29 PM »
Haha I bought those motors.  You'll need to make (or buy) a gearbox for them to be useful, so the price per USEFUL motor is a bit more than you'd think.  Still cheaper than buying most geared motors I've seen, but it's a PITA.  I ended up buying gears from american science and surplus's website. (Google it and search for gears).  Like I said, you have to be very crafty and decently skilled at construction because the gears have to line up REALLY well.  

LEDs are LEDs are LEDs are LEDs (most of the time).  

You'd probably get sick of red quickly lol.  When I bought my assortment I bought this.  (I have no idea why this wasn't in the "LED assortment" category.  I actually had trouble finding it.)

http://www.goldmine-elec-products.com/prodinfo.asp?number=G17169

A bit more expensive per LED than yours, but yours are all mini leds, while with mine I get a bit of everything. (Mini, normal, large, square, red, green, yellow, orange)  I haven't put a dent in them yet.  I don't know if mine was the best deal on the site, but most of the time LEDs just make things look cool, so I try to do without them.  I mean how many "Power on" leds do you actually need?   ;)

One thing that I never thought about when I was first starting is debugging.  How are you going to set up something quickly to tell if the ADC is working correctly, or if your sensor is giving good data?  Since you're looking to hook up to a computer you should be good but... a simple 7/8 segment display is very useful.  Sure, it's not extremely easy to hook up (it requires at least 8 open I/O pins), but it's EXTREMELY easy to use.  (So is a blinking LED, but that gets annoying REALLY fast.  "Did that blink twice, or three times... GAHHHH")
« Last Edit: July 13, 2011, 02:45:36 PM by corrado33 »

Offline CompChemEngTopic starter

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Re: What parts should a beginner buy?
« Reply #12 on: July 13, 2011, 03:34:38 PM »
Webbot,

I'm definitely interested in the high-level side of AI.  Honestly that's half the reason that I'm here: I need to make a body for the darn thing.  (The other half is more career-related; I need to figure out how to get my lab instruments to interface with my computer.)  Despite my comfort with creating programs, I just don't have experience with putting circuits together.  It's that sort of experience that I've been hoping for here.

After a quick look at your site, I'm really interested in what you're offering.  I'm going to spend a while reading over it.

PS-  I have a powerful interest in being able to assemble a robot that'll constantly send off its input and such to a PC and then having that PC being able to return commands to the robot.  Wireless is greatly preferable but I'd be absolutely thrilled to even have a wired version.  I pretty much figured that I'd have to learn robotics and make such a thing from scratch.  But if you have any sort of guide or even just hints at how to move in that direction, well, I'll be sincerely grateful.
« Last Edit: July 13, 2011, 03:43:50 PM by CompChemEng »

Offline corrado33

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Re: What parts should a beginner buy?
« Reply #13 on: July 13, 2011, 04:38:39 PM »
What you want to do is actually pretty easy.

I don't know if there are other ways to do it, but I'd use a microcontroller to collect and analyze the data from one of the lab devices, then send it (maybe via. bluetooth), to your computer.  Then use a program on your computer to output it to something pretty you can see.  And maybe send something back to the "device".  

EDIT:  Oh, BTW, you don't need to learn "robots" per se, just how to program microcontrollers.  If you know any sort of computer programming (basic, C++ etc), you should catch on VERY quickly.  You can program MCUs in C (which is what I do).  Webbot's library is VERY useful, and makes the learning curve slightly less steep when starting to program MCUs. 
« Last Edit: July 13, 2011, 05:06:34 PM by corrado33 »

Offline CompChemEngTopic starter

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Re: What parts should a beginner buy?
« Reply #14 on: July 13, 2011, 05:18:51 PM »
corrado33,

That sort of setup would definitely work!  Though I'm not sure what to buy or how to put it together.

PS - (To your PS =P):  Yeah, I've done projects in BASIC, Visual Basic, C++, Visual C++, C#, VBA, Matlab, and Java.  C++ tends to be my default language, and I'm very good at quickly picking up new languages.  If I can get the hardware together and some sort of way to put any type of code into the chip, I should be set.  It's getting to that point that's the problem.

I get the general idea that I'll need a microcontroller to program, that I'll need engines/servos to move stuff, that I'll need a battery to power it all, etc.  But when I look at a website to buy such things, I haven't a clue which specific ones to buy.  I think that I get batteries and servos now, but I'm still trying to figure out the others.  And I haven't a clue as to how to even figure out which resistors, capacitors, voltage regulators, etc. to get.
« Last Edit: July 13, 2011, 05:35:45 PM by CompChemEng »

Offline corrado33

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Re: What parts should a beginner buy?
« Reply #15 on: July 13, 2011, 05:30:25 PM »
Well, what you buy and how you put it together depends on exactly WHAT you're interfacing with and how it communicates.

You can't just buy a MCU and expect the same code to work with all of your lab devices.  (Unless they're all made specifically to communicate in the same way.)

So, with that said, what are you trying to communicate with?  What kind of ports does it have?  Does it have a usb port?  Does it have a serial port?  Do you just want sensors?  Are you trying to monitor temp and pressure?  How can you "tap into" the instruments?  I'm guessing these things aren't like Mass Specs or UV-viss or IR specs cause those already have computer hookups.  (Unless they're ridiculously old)  So I'm thinking you need to interface with slightly simpler things.  

I'm assuming you're probably not supposed to talk about exactly what you do at work (as most things in the chemical engineering field are probably proprietary), and we're not asking you to tell us everything.  We just need more information before we can even think about creating a circuit or program.


(Also, you might want to start a new thread since we're completely off topic here.)

Offline CompChemEngTopic starter

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Re: What parts should a beginner buy?
« Reply #16 on: July 19, 2011, 02:22:53 PM »
corrado33,

I'll start a new thread on the other line of questioning later once I've built the $50 Robot.  Doesn't seem like it's fair for me to ask for a spoon-feeding when I haven't yet done the minimum necessary to achieve a basic understanding.

This said and back to the topic of the thread, I've got everything except the soldering iron, the solder, and the battery charger.  I've put them off to last since I want to spend cash to get the right parts, yet my college-student self is reluctant to spend a few hundred dollars when I'm not entirely sure that what I'm ordering is what I need.  (I've been down that road before.)

So will this charger charge this battery pack?  (I've already bought two of these battery packs.)  The specifications on the charger's page say that it charges "1-24 NiCd, NiMH (1.2-28.0V)".  The voltage range looks good since it's a 6V battery pack, but what does the "1-24" refer to?  Also, will I need some sort of additional adapter or wire to hook up the battery pack's Hitech connector to the charger?

My other question would be about soldering irons.  The SoR website seems to recommend that a serious newbie invest in a good one with an adjustable temperature range and tips that can be changed out, though I'm not sure what temperature range I should look for.  Some soldering irons boast about being hotter than others; is there a lower or upper limit that I should be concerned with here?

Also, with solder, what are the different kinds?  What should I be using?  Should I avoid solders with lead in them, or do all solders contain lead?

Thanks again!

Offline corrado33

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Re: What parts should a beginner buy?
« Reply #17 on: July 19, 2011, 02:36:23 PM »
Yes, that charger would easily charge those battery packs.

The 1-24 refers to the number of "cells".  A cell is just a single battery.  Think about it this way, if your tv remote control takes two AA batteries, it's running off of a 2.4V battery pack right?  Each individual battery is a "cell".  If you look at the number of cells (1-24), and multiply the numbers by the voltage of a single AA battery (1.2V) you'd get 1.2 - 28.0 V, correct?  (With a little cut off of the top).  Since you're using a 6V battery pack, it has 5 cells.  You can probably count them.   :)

Yes, you would need some kind of connector between the output of the charger and the battery.  The output of the charger is two female banana jacks.  So if you could get a banana plug to hitech if you wanted, but you could EASILY build a connector.  Buy two banana jacks, like these...
(Found mine at radioshack, expensive there but whatever, it's only a couple bucks)

Then buy some banana plug ends.  Like these... you need four.


Make two decently thick wires out of the four banana plugs.  Then mount the banana jacks to something (a plastic project box maybe), and run two wires to some header pins that you can plug your hitech connector into.  Make sure you label which one is which and which way to plug in your connector.  The charger DOES know if you hook them in backwards, but still, it's good practice.  You should probably have extra header pins from the $50 robot. 

Easy as pie.   :)

You could build it from radioshack for <10 bucks, or if you buy the things online probably a lot cheaper.  Or you could just buy an adapter. lol 

I actually wired something similar up for my charger to be able to charge a bunch of different AAs and AAAs.  Just make sure you use wire thick enough to handle the power you're putting through it.


As for the soldering iron... I bought one from radio shack years ago.  A variable temp one would be nice, but you can get away with cheap ones.   :D
« Last Edit: July 19, 2011, 02:38:54 PM by corrado33 »

Offline CompChemEngTopic starter

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Re: What parts should a beginner buy?
« Reply #18 on: July 20, 2011, 04:48:17 PM »
corrado33, awesome, thanks!

And for wires - do you know where I should buy a bunch of wires from?  Both wires for use as connections in circuits and some of the "decently thick" wires for connecting the battery charger to the battery with the banana jacks.

Offline corrado33

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Re: What parts should a beginner buy?
« Reply #19 on: July 20, 2011, 05:13:55 PM »
In all honesty, I have no idea where good deals on wire are.  I bought a bunch of... 22 gauge maybe... maybe 18 or 20 gauge wire from radioshack a long time ago.  Came in a pack of red, green, and black.  It's solid core, so it's not all stranded like speaker wire would be, and that's good for using a breadboard.  I haven't needed any since.  But if you're buying a bunch of stuff online you might as well get some jumper wires, as they're made for use on a breadboard.  Or you could buy some wire, cut it into 2-6 inch sections and strip the ends of each wire to make your own.  :)

As for thicker wire, you're on your own.  Sorry!  I purely speculating now, but I would imagine you wouldn't need more than 12 or 14 gauge wire to be safe on the charging wires.  Probably even thinner than that but I'm just being cautious.  (Sure we could calculate the heat loss with a given current but... yeah I don't feel like doing that right now! lol

 


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