Home made equipment - Page 1
Forum section: electronics / beginners

author: David Aurora
author_rank: Frequent Contributor
timestamp: January 01, 2012, 05:18:25 am
content: Just kind of wondering out of curiosity how much of people's equipment is built/designed by themselves and the way it gets used (e.g. gets you by for a few months while learning until you can buy better, or becomes a permanent part of your bench etc.).For example (and a beginner's perspective), lately I've been keeping an eye out on eBay for a function generator. This would replace my home made super simple one (based on a 555), which replaced my iPhone running a sig gen app, which replaced just connecting whatever random source I could patch in. As I've been learning more about the circuits I'm working on and the tools I use to do that (scope, meters etc.) I've hit the point with each setup where I go "OK, what I'm using is lacking feature ______, which would really make this easier. Time to get a tool that will do that". And now I'm at the point where it's not enough to just know there'ssome kindof signal flowing, or havebasiccontrol over frequency range, I need something where I can go "I want this frequency, at this amplitude, with this shape. Bam.".And that leads to this question (though this is just an example, it's not necessarily a post about function generators specifically). I'm at the point now where I really want the features I see on "proper" units, and I know I could either have a crack at building one or just bite the bullet and buy one. I know I'd get more of a kick out of building one, and learn a lot about the topic. But I also know that by the time I'd finish one I would know more about the topic and start planning a better one in the back of my mind, and that process never really seems to end haha. Plus I know I won't design a better one than the ones on the market, though it's questionable whether I need that level of quality just yet anyway. So I wonder if there's a line in the sand where smarter people than I would just go "OK, it's a tool, you don'tneedto know everything about the guts of it and build your own, just buy the damn thing and get on with jobs you want the tool for".I've definitely noticed these thoughts with bench supplies I've built, or little handy home made boards I've got scattered around the bench like rectifier circuits or rail splitters or voltage dividers that I can connect as needed. There's enough of this stuff laying around now that it probably would have been much cheaper and faster to have just bought an off the shelf bench supply ages ago, but then again I might not have understood the guts of power supplies the way I do now if I'd done that. From the point of view of education, this stuff seems like an absolute bargain in retrospect.So yeah, how do other people draw that line of DIY vs off the shelf? Cost? Time? Level of geekiness? A known standard of accuracy with a store bought thing? Custom features? I tend to be missing that part of the brain that admits defeat when it comes to doing things myself, so I'm curious about how it stacks up in the long run. I'm not opposed to either buying good tools or building what I need, but more just curious about which is more beneficial in the long run when you weigh up knowledge, cost, wastage etc.

author: amspire
author_rank: Super Contributor
timestamp: January 01, 2012, 06:10:37 am
content: A lot of this comes down to the getting the best results out of your efforts.You can definitely make a good power supply yourself, and you can save a heap of money, particularly if you have some good parts lying around.It is possible, but hard, to make your own function generator that matches the modern commercial ones.Something like an oscilloscope is verging on impossible to make yourself with a sane amount of effort.If you really have a love for function generators, and over time, you will probably build several with the aim of perhaps an OpenSource or even commercial design, go for it.If function generators are not your real passion, here is what will happen. You will spend 2 to 6 months building a generator that will work OK. In 12 months, you will need something better so you will buy one, and the home built version will go into a cupboard for the next 20 years.In many cases, if you have the money, it is better to go straight to the project you really want to do, and buy the tools that you need to do so. Don't get sidetracked building a function generator, if it is stopping you from working on a project that means more to you. You would learn a lot building a function generator, but you will learn just as much using a good function generator as tool to help build a different project.Richard

author: FenderBender
author_rank: Super Contributor
timestamp: January 01, 2012, 09:51:22 pm
content: Power supplies are definitely feasible, and things like dummy loads for testing. You can also try some other little analog type meters like for ESR, etc. Function generators are possible, though for the price you can probably get a decent cheap digital one. Oscilloscopes are essentially impossible, and impractical for what you can get a cheap analog scope for. And you'll probably have to repair or toy around in that scope so you might learn something there.I think a good compromise between buying and building would be to buy old equipment that might be in need of repair or restoration and work on those. You will probably get a more functional product than if YOU designed it from the ground up, and it will most likely be cheaper than a brand new piece of equipment and will let you learn more.That's my theory.

author: wkb
author_rank: Super Contributor
timestamp: January 01, 2012, 10:27:15 pm
content: I recently built myself a little LC meter based on a PIC chip w/ LCD. Couple of hours to bread-board it together, and useful to have.This kind of stuff I think is worth building yourself, if only for the satisfaction it tends to give. Obviously building T&M kit should not distract you too much from what you *really* wanted to build

author: tekfan
author_rank: Frequent Contributor
timestamp: January 02, 2012, 12:34:05 am
content: Quote from: FenderBender on January 01, 2012, 09:51:22 pmI also think that you get the best of both worlds if you buy old test equipment and bring them back to life. For older equipment there are almost always manuals with detailed description of operation. You often see very elegant circuit designs with the explanation on how the circuit works. When you fix something you get a nice piece of test equipment and also obtain knowledge on the actual circuit that you fixed.

author: McMonster
author_rank: Frequent Contributor
timestamp: January 02, 2012, 02:42:00 pm
content: Quote from: tekfan on January 02, 2012, 12:34:05 amI totally agree. That's exactly what I'm doing with my function generator and I'm happy with this approach. The only catch is that you need to already have some basic experience with electronics, you can't jump right into repairing old devices as they tend to be just complex.Building something from scratch is usually the best approach for to start with, you can't really avoid producing barely useful or useless circuits if you want to learn something. After you did this for a while it's your decision to build or buy, as you'll have enough knowledge and experience to know what's the best.

author: Unknown
author_rank: Unknown
timestamp: January 02, 2012, 03:53:48 pm
content: Considering your future and present projects would set the criteria, for test equipment you would need... e.g. a signal generator can be produced using a Single Chip; the XR2206 is good up to 1.2 MHz in my experience, but would need some additional amplification for it's 1 volt output to higher levels... here is where the design bit comes in, using an Op-amp and output A-class transistor, see URL:http://www.eleccircuit.com/xr2206-function-generator/this site has circuit info, and just Google around for the XR2206, there's lots of detail available.

author: David Aurora
author_rank: Frequent Contributor
timestamp: January 03, 2012, 11:20:15 am
content: Thanks for the ideas, I'll be back to this thread first chance I getThe idea of reviving old test equipment is so logical I'm embarrassed it didn't occur to me before haha! Probably a bit of self doubt there too I guess, but realistically I should be up to a lot of basic restoration jobs at this point without too much brain explosion risk

author: Ajahn Lambda
author_rank: Regular Contributor
timestamp: January 03, 2012, 03:22:29 pm
content: Just a quick bit on reviving or tinkering with old equipment for your own uses [and from my experience]: try to find a design that someone else has already torn down and played with (or better yet, a passionate group of someone-elses). This way, you're not stuck with a crap design that's known to do bad things, e.g. catch fire, fall out of spec, break easily, etc. It also ups your chances of finding replacement parts or upgrades.Let others with expertise do the 'hard work'; it's easy as a beginner to get discouraged, so I prefer that people learn in the easiest manner possible. Quite the opposite method of my university professors. :p Don't worry, there are plenty of hard-learned lessons out there to explore, and we're in no worry of running out soon.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: January 03, 2012, 03:38:22 pm
content: Advantage of getting 'real' equipment is that it keeps a decent trade value,while market value of homebrew stuff is practically zero.

author: saturation
author_rank: Super Contributor
timestamp: January 10, 2012, 12:52:29 pm
content: Buy whenever possible.Your builds are only as good your tools.Imagine building a simple wooden box, how would you build it without tools? make your own hammer? nails? saw? What quality would the box have with DIY tools? How long would you work on making the tools? How soon do you need the box? Would you build from discarded metals or mine it and forge it? Where is your forge? What will you use to shape it with? etc.,The same goes for T&M in electronics, these are the tools that build the circuits, and if you make your own the quality of designs using these tools are limited by the quality of the tools.If you don't know certain key techniques that are core to electronics, build such devices to a prototype level to understand the principles, then once completed and specs are stable, disassemble and reuse parts for the next project. One of the most expensive parts of builds are just the case and hardware: knobs, feet, dedicated PSU, jacks etc., and often exceed the cost of just the electronics and its PCB.

author: nrgeek
author_rank: Contributor
timestamp: January 24, 2012, 09:03:04 pm
content: Ok on this note .. I have yet to build my first project ..Im still just absorbing info .. and man is there a bunch to absorb ..I was wanting a signal generator, to use in combination with my used tektronix 465m 100mhz scope .. but there are so many options and money is very tight .. wife bitches about what I spend on hobbies etc .. lord knows I have many pricey ones lol ..boats, cars, computers, fishing, etc so I mainly fund my stuff I want from wheeling and dealing .. barter .. ebay etcGetting off topic lol .. I do that alot ... what I need to know is what would be a good signal gen, for testing capacitors and other such things that my arise in the near future as I dig deeper into this new /sorta old to me hobby..I will be mainly repairing lcd, plasma tvs and computer lcd screens, cell phones, laptops, desktop boards etc.. junk I pickup at local recycle places free, or dumpster diving forbut also want to do more in as far as building projects from scratch as well .. or mods to existing stuff .. bench power supplies, maybe some linux based projects, ccd cameras , just small projects that will come in handy to me .. Im a computer tech and IT systems/network manager by trade so there are quite a few things Ive seen that all this knowledge will benefit from . Hell Id like to even build my own fish finder that would be a cool thing to meAnd one Ive yet to see any one here or other blogs do .. may have I just haven't seen it yet.so which is better or should I get both or are they one in the same function gen and signal gen.. I keep seeing both mentioned over and over .. signal gen seems to pop up more ..Id like to find a used one rather than building one just yet .. and fix it .. there are so many types etc .. what would be a good starting point as a beginner price being the biggest factor would like under 50 bucks.. Ive seen really old stuff .. a bunch of old heathkits, wavetek, hp, tek, barco and on and on ..with all kinds of descriptions Multi Frequency Cross Hatch Signal Generator, rf sig gens, Sine and Square Wave Audio Gen, Sweep Generator & Marker Generator, video gens, ntsc gens, with just as many or more specs .. Info over load lol ..Then you have the AD9850 signal gen boards from hong kong stuff with lcd and with out lcd0.01Hz~2MHzHELP lolI just want to have the basics at hand when I need it .

author: saturation
author_rank: Super Contributor
timestamp: January 24, 2012, 11:29:31 pm
content: This may help. There is also a kit version or just the DDS module, just check eBay offerings.https://www.eevblog.com/forum/projects-designs-and-technical-stuff/inexpensive-calibration-references/msg84388/#msg84388