getting started on hands-on projects - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: February 13, 2010, 12:52:10 pm
content: hi folks,Just bumped on to Dave's page via Tom Haye's course page (of AoE fame )... first off, kudos to Dave's video blog- real value infotainment!Ok, a quick intro about me- I'm a newbie IC-design engineer working for a niche audio-codec company based in the UK. I hold a master's degree in microelectronics. I belong to the generation of electronics engineers who did little hands-on tinkering in their teens.. and even in engineering school, it was mostly theory and not much lab work. I guess many would be familiar with this tribe - who are raised on a diet of spice simulations!So, today I find myself stumped that I don't get it how "it's all done in the lab".. I was almost embarassed i couldn't set up an eval board at work for a chip I helped designOver the years, I've been meaning to teach myself hands-on by building some projects etc.. but have procrastinated to no end... not just that I was lazy but also, I was overwhelmed by so much complexity out there.. didn't know where to start from??!So, here's my appeal to all experienced folks out there to give me some tips on getting started with hands-on electronics- starting from buying tools and basic instruments to set up a mini-lab, to suggesting audio/analogue projects (that's what I like most) which will help me enjoy 'doing electronics'!

author: DJPhil
author_rank: Frequent Contributor
timestamp: February 13, 2010, 03:12:23 pm
content: My experience so far in life is limited to repair and recycle, and I'm only just starting to get into the design side. Your question was very broad, so I'll try to spread it out into chunks that are easier to focus on.Tools:I'm going to assume you've got a basic assortment of screwdrivers, pliers, wire strippers and cutters, and the like. If not just speak up, this is something that doesn't get mentioned often, and could probably bear some in-depth coverage.Equipment:Solderless BreadboardUsing point to point wiring to make everything nearly cost me my sanity! This was the single most important thing for me. I picked up a pair of 830 point boards with a jumper wire assortment for ~$20US.Soldering IronI'm using a twenty year old 'hot nail' from Radio Shack, and will someday upgrade to a Hakko 937 or one of it's clones. I've read that it's much easier to learn to solder with a good temp controlled iron, and I believe it. I use my iron for desoldering salvage parts for the time being, so I can get away with an old cheapie to some extent. Fine pitch surface mount soldering with a 'hot nail' would be somewhere in between a bad idea and impossible for all but the most skilled. The cheapest irons are available in a hardware store here for about $12US and a decent Hakko clone capable of lead free soldering should be available for less than $100US.MultimeterThis is the place to learn about multimeters! I won't repeat the advice already here, but this is definitely on the list of things needed. I'd advise doing some research to narrow down what you need, and getting the best one you can afford that does what you want. I'd say that multimeters can roughly be categorized into <$30US, $30-$150US, and awesome. Each range has it's uses, and you may find deals all around the price ranges.Power SupplyMy approach here was to salvage an old computer power supply. I'm sure you know to be careful around mains voltage and big capacitors, but it's worth a mention for others who might read this.Every power supply I've dealt with has a list of it's max amperage ratings per voltage rail on a sticker on the case, so it's easy to see what you're going to wind up with. Given you'll be dealing with audio, it's worth noting that computer supplies generally only support a few hundred mA on their -5 and -12 rails, so you'll probably have to buy or build something yourself for a good split supply. Commercial power supplies are available starting from a bit over $100US, and it's possible to get lucky at a swap meet or on ebay.OscilloscopeLike the multimeter, this is the place to learn. I don't have one myself (yet), but I'd advise researching the benefits and drawbacks of used analog vs. new DSO. If you're on a budget, you can get a lot done in the audio ranges with an older analog, but it's buyer beware out there on the auction sites. Older and used scopes can come your way for any price down to 'free to a good home', but for something new you're looking at a minimum of ~$400US for a standalone, bench scope. There are USB scopes and scopemeters out there for less, but they compromise somewhat heavily on their specs for their affordability (in my opinion).Function GeneratorI know little about the ins-and-outs of function generators, so I won't say much. In a pinch, you can use your computer with various software for simple audio generation, just beware of it's limitations. I haven't researched prices, as this is farther down my list of priorities.Parts and consumables:SolderThere are a heap of different types of solder, and in your case you may be forces to use lead free soon. Others may have more advice to give here, I'm using scrap lengths of rosin core industrial wiring solder I get from an electrician friend. Not recommended.DesolderingDesoldering can be accomplished with a suction bulb, suction pen, desoldering wick, or suction machine. Many would advise picking up a pen and desoldering wick, and this is plenty to get started. Bulbs are a bit kludgy to work with, and the dedicated machines are usually part of an expensive soldering station.Iron TipsIf you decide to go with Hakko, for example, there is a huge assortment of tips available for different needs. If you get a Hakko clone, try to ensure it's capable of using Hakko replacement tips. Hakko makes very good, long lasting tips, and this is a good way to squeeze some value out of a cheap clone.Tip CleanerMany use the moist sponge method, some report awesome results using the flux impregnated Hakko brillo pad looking things. I use flux soaked steel wool, and I don't recommend it.FluxRosin core solder, when melted, boils off the flux in it's core. This is the smoke you see when soldering, for the most part. When there is no flux present, solder tends to become clumpy and resist sticking to anything but the iron. Flux is essentially the 'water' in watercolor painting, you put it where you want the solder to go. You can get flux in many different forms: 'big bucket of flux', small tin, flux pen, needle tipped squeeze bottle. I use a small tin myself, but I primarily do desoldering work thus far. Watching some video tutorials on soldering will help determine what you need for your own uses. Just be sure to stay away from 'acid' flux, it's intended for pipes and such and will eat plastics.WireYou can't have too much wire! You can easily salvage more wire than you'll ever use from construction site waste, and buy only what you specifically need. One good example here is household telephone wiring. Older wiring when I live used 24AWG solid core wires, so I saved about six feet of a ten pair bundle and I've got enough breadboard wire to last forever. Various sizes of insulation become useful for temporarily connecting parts with leads, you just slip the leads in each end and if you used the right size insulation the connection will stay together hands free. There are many great improvisation opportunities here. Or perhaps, I'm just a bit nuts.Discrete ComponentsOh, you could buy them, but I recommend at least a short salvage operation. It seems like all the folks who learned hands-on first started by taking things apart. It's when curiosity kicks in that you start learning things. Why is there fuzzy plastic debris on the end of every screw I remove? How could this thing even work with a spider egg sac on the IC?! What's the series resistance of that spider egg sac? Grab the ohmmeter! If you start pulling discrete components it's a decent introduction to solder behavior as well, and a relatively painless way to learn how not to overheat parts.Stuff to take apartAsk everyone you know to save you broken things! Everyone! You'll have a never ending stream of awesome built up after a while. If you're just getting started you can try any swap meet, flea market, thrift store, etc. Try to aim for older and larger things when possible, as you won't have much to do taking apart, say, an ipod. You're looking for '80s and '90s consumer electronics, old stereos are a good place to start.Bah, I suck at organization. Anyhow, I hope this helps some. I'll be here to continue the dialogue if you have more to ask, I'm just not sure where to start rambling.

author: xani
author_rank: Frequent Contributor
timestamp: February 14, 2010, 02:58:31 pm
content: As for Function Generator and Soldering Station, good exercise would be to build one ;]. For audio worl u wont need anything more than 100kHz and that is easily attainable using chips like XR2206. For soldering station u basically need soldering iron with thermocouple ( i bougth mine for $10), 24V transformer and some standard parts.

author: Unknown
author_rank: Unknown
timestamp: February 14, 2010, 09:56:33 pm
content: Thanks a lot, DJPhil for your detailed list of tools, equipment and parts for startersI do have a basic tools and multimeter, I will start off with these and use the scope/power supply at work for now.I was looking athttp://www.vakits.com/index.php?cPath=43&osCsid=f2caf7eb2191c42087dea24515441477seems a useful place to gather parts and build something useful.The real barrier is to shake of my lazy bones and actually start building!!

author: DJPhil
author_rank: Frequent Contributor
timestamp: February 15, 2010, 12:12:36 am
content: I'd never heard of these folks before, but I like the way they put the kits together (like this one). Nice and cheap too! This seems like a good way to go if you want to start by creating instead of destroying.Quote from: xaniExcellent idea!I gave a halfhearted look into trying to build a soldering station just as you describe, but I couldn't find a well trodden path explaining the inner workings. This is an example of where I'm a complete noob: basic design. I'd definitely build something myself if I could sort out the guts well enough to be reasonably certain that it was ESD safe and I could calibrate it roughly with a multimeter temp probe. I'm going to guess that the thermocouple output is attenuated by a potentiometer and used to control the duty cycle of a PWM power circuit. Am I close? Would you be willing to tell more about how you made yours?

author: xani
author_rank: Frequent Contributor
timestamp: February 16, 2010, 12:31:03 am
content: In my case it was just OP-07 for amplifying thermocouple signal (have to be precise amp, coz signal is very small), comparator (plain opamp), potentiometer + optotriac and triac for turning off/on power to iron. It didnt had any reference soure (xcept stabiliser) but +-10 C isnt that inportant in soldering.Or u can just hook up output of OP-07 to some micro and have nice display on LCD/LED, just use something with internal ADC.As for steering, its simple, if signal after x100 amplification is lower than what u set up on pot it turns power on, if its above it turns power off, so it doesnt use PWM, just switches on/off 24V AC directly from the transforomer. Ive used optotriac that switch on zero crossing so it wont generate too much interference (to be exact "MOC3041M Triac driver+zero voltage crossing")So in short its 2x12V (had that one in junks, you can use 24V one) 50W transformer, 7812 and 7905 stabiliser (didnt had 7912), amp (have to be with low offset voltage like OP07), comparator, pot, optotriac->triacMine iron is PENSOL-IRONE-N (there is also PENSOL-IRON-N which is non-ESD version of that) and it have normal thermocouple so u can pretty easily calibrate it using meter with temp function. Mine had 2 leftmost pins for power and 2 rightmost for thermocouple, middle was ground connected to one of thermocouple pins

author: DJPhil
author_rank: Frequent Contributor
timestamp: February 17, 2010, 06:11:38 am
content: Thank you Xani! I'm sorry I didn't post earlier, but you've got me pointed in the right direction and I took right off. I'm learning a lot as I go, and answering a lot of my own questions. I just wanted to thank you for getting me started.I've spent a lot of time poking around on sites like Make and Instructables and I've never seen a writeup on an adjustable solder station that didn't involve a lamp dimmer. If you're ambitious you might consider writing this up for one of those sites, I'm pretty sure it'd be a big hit.It looks like the tough parts for me will be the transformer and the iron. I couldn't find a US reseller for Pensol, but there's a company called Ayoue that makes knockoff Hakko irons. I can get one of their replacement five wire irons for about $20US, and as a plus they are compatible with Hakko tips (which I've heard good things about). I spun through a couple of local salvage company inventories looking for transformers and they don't seem to have anything strong enough. I also was treated to a dizzying spin through the details of volt-amps and power factors, which I need to go back and relearn until I understand it completely. I'm going to speak to my electrician buddy and have him bug their instrumentation guys, as I believe they do quite a bit with 24vdc.Thanks again for giving me enough to work with without spoiling the ending, I'm going to enjoy hammering out a schematic and tweaking it to suit!

author: xani
author_rank: Frequent Contributor
timestamp: February 17, 2010, 12:29:10 pm
content: 24vdc ? You mean 24vac i think ;p.As for my station I just saw project based on micro (google translated to englishhttp://translate.google.pl/translate?hl=pl&sl=pl&tl=en&u=http%3A%2F%2Fwww.elektroda.pl%2Frtvforum%2Ftopic1426196.html) and thougth "Okay i dont need display (for what ? i just need LED that shows me it have temp set up on pot, using uC for doin "on zero" switch on of triac is pointless as u can get optotriac doin it for you), setting temp by pushing buttons is pointless, and normal on-off regulation is enougth for me" so ive done it analog way. Hmm now im thinking about mounting "Analog" voltage meter to show temp ;].About transformers, anything >50VA be it 2x12 or 24V is enougth, just remember that in case of 24V transformer u need to use voltage doubler to get symmertical powerhttp://en.wikipedia.org/wiki/Voltage_doublerunder "bridge circuit"