Is it a good idea to DIY build everything else after buying an oscope and DMM?

[jaqie]

Hey there, all.  A little info about me that may be pertinent to answering my question.
---------------------
I am disabled on disability, so money is EXTREMELY tight to put it lightly.

I have been a PC technician before I became disabled, and am a PC hardware expert.

I used to want to be an electrician, so I know a hell of a lot about electrical stuff, am easily able to wire a house to code and such.

I had taken but not finished (health issues) electronics in college, never really learned much beyond diodes and caps.

I happen to have an IQ of 170, and am a very physical learner - if I see it done I can figure out how to do it myself... which leads to the problem below.

Software is my weakness. I learned MS Qbasic in high school in 1990s when it was all that was taught,and taught myself TRSDOS from TRS-80, but have been totally unable to learn anything newer ever since... I just can't wrap my head around it because it isn't in physical space and I can't see it physically to understand it.

I have a deep and keen interest in making my own electronics gadgets and gear, especially power supplies and computer interfacing gear.

A note on the above: most people getting into it now would only want to do USB, not me.  I am also a huge fan of old PCs, I built a 386 from parts recently and it is my pride and joy - running stuff in DOS and using LPT and COM ports would be just as fulfilling to me as working with USB gadgets.  Reminder I used to be a pc tech, and am now a hobbyist, I have from 386 all the way to my 6 core gamer pc, so not just old stuff for me!

I have done many, many bodges and minihacks and such with basic electric mods, such as wiring an ATX power supply to set off a 12v relay to control a 110v internal water pump, fixed many broken electrical devices, built my own workbench 110v distribution system, et cetra.

I have never been able to build a single electronics device which involves anything more complex than diodes resistors and relays that works - I tried making an LM317 PC fan auto temperature speed controller to miserable failure.

Remember, budget is a HUMONGOUS weakness for me. Please remember that when recommending....

I have a basic radio shack DMM, model 22-813, and a kill-a-watt p4460, a basic 35 watt pencil iron, a weller 140w nichrome soldering gun for heavywork, that is all I have right now.

What I want, to start at least, is a better DMM (fluke would be awesome, but budget), an oscope (either used 20MHz dual trace or the rigol DS1052E if I could find a way to save up), a basic soldering stand with temp control, and one of these:
http://www.freetronics.com/collections/all-products/products/etherten



After getting those three things and a buncha parts for prototyping and making my own stuff, I wanna start with making things like a good bench power supply, one of those ESR meters, decade resistor boxes, et cetra building up my own tools as I go along.

Thank you all so much for reading this far and trying to help me!  What do you all advise?

[FJV]

Why not start with something different first, before spendig serious cash?

My advice would be to buy a breadboard.


This way you could make a lot of electronic circuits that interest you and after you're done you could re-use the parts.
Or if you really like the circuit solder it to a pcb. It also makes your pcb's succesfull more often as all your circuits ideas have
been tested before on a breadboard. It reduces the amount of parts you buy and save money.

As for your multimeter, it is fine for a beginner projects (low voltage, no huge accuracy needed).
After you learned a little more you can really understand what your specific needs for equipment are.

One thing I like about my cheap multimeter is that it is based on and ICL7106, which means I can download the chip's
datasheet and know my multimeter in a larger detail than what would be normally the case.

[ee851]

Yes, I agree.   A breadboard is your next tool.    That and a cheap pair of wire strippers (99cents at Harbor Freight) for stripping the 24 gauge wire you will put into the breadboard.   I am a poor American too.    A lot of my inspiration pertaining to electronics comes from pcbheaven.com     Giorgios has posted many good how-to videos on his electronics projects there.   Highly recommend them.

[jaqie]

I...already have a breadboard and some high quality wire strippers...

I was asking what is in the title...  about making my own equipment.

Sorry I wasn't clearer.

I said I am a pc tech and do electric work myself to show I already have the general tools that would be handy around, I am most interested in people's opinions and suggestions re building my own equipment or having to buy it, and maybe some ideas for really cheap equipment thats worthwhile to build first considering what I have equipment wise...

Thanks for the advice, it is appreciated, sorry I didn't mention everything I do have in detail, just too much to mention.

[alm]

DIY builds are often more expensive than low-end commercial equipment (made with cheap parts and labor in China), unless you acquire the main parts for free / surplus. For example, a basic linear power supply would need a big transformer, heat sink, power transistors, binding posts, case and panel meters. Add the costs of these together and you've probably exceeded the costs of a basic commercial bench supply. You could do it for cheap by converting an ATX power supply, but the specs will be far worse (limited to 12 V max, no current limiting, only fixed voltages, poor ripple/noise specs).

[jaqie]

There is no way I can afford one of those retail linear supplies, I was going to base my first power supply projects off of a good ATX PSU and build supplies with that as a base device... and work on scrounging parts from places as I learned.  Cases are not a problem, I am great with that kind of thing.  Current limiting would be easy with an atx psu as a starting point, just a good constant current source and adjustment device, I can even use my meter instead of a display at first, and maybe build an LED display for it out of cheap 3mm LEDs I can get from goldmine-elec.com .  I can be inventive here, Im good with that kind of thing.  Heck, I could even use some PC CPU and video card heatsinks to spend $0 on those.

I am extremely adverse to buying those cheap chinese retail devices for my equipment, as dave says it's measurement confidence with multimeters, it's the same sort of thing with this equipment.  It's either good equipment or equipment I build myself here. To build or not to build, that is the question.

[PaulAm]

You just need to polish your scrounging skills.

If you can find some dead UPSes, you have 90% of what you need to make a great power supply (transformers, case, rectifiers, caps, etc).  The only thing that would cost some money is the parts for the regulator circuit that you wanted to add.  And that can be as simple or complex as you want.  Or you could start simple and refine versions adding features as you go.

Often, you can find quality equipment that doesn't work and fix it yourself.  For one thing, the exercise in tracking down problems teaches you a lot about how things work (and how they break).  And, when you fix it, you have the satisfaction of having high quality equipment purchased for peanuts.

I very rarely pay over $50 for scopes, for example.  Mostly these are Tektronix 4xx and 7000 series analog scopes, although I recently picked up a 2432a DSO for $50 that required $0.50 in parts to fix.

Put a wanted add in your local Craigslist, you might be surprised at what shows up, maybe for free.  Heck, if you were around me I'd give you a trunkload of electronic scrap that's been piling up but too good to landfill.

Check your local universities; some of them have surplus property disposition sales.  You never know what you can find there and it's often very cheap (I picked up a couple of Heath lab power supplies at a local University for $20 each).

[jaqie]

Awesome, thank you PaulAm!

I will most definitely try an electronics/tools post wanted in CL and try to get myself to a local university used equipment sale, if I can find info on them from googling and calling around.

I actually have a pair of APC backUPS 600 here I bought from the local goodwill for $2.50 each I have been waiting for spare funds (heh what's that?) to get new batts for.  Maybe I could repurpose one!

[PaulAm]

That's a good start.

Another good source of parts are old printers.  You can get stepper motors, controller ICs, power supplies, etc.  I once bought a pallet of old dot matrix printers for $5 at a school surplus sale and I have a lifetime supply of small parts (not to mention hardware).  Nobody wants old printers.  Data sheets can be found online for most parts.

If you're not proud, drive around the better neighborhoods on trash day.  I found a nice 25 disk stereo system that way.  I loaded that up with $1 CDs from the library sale and put it in my work area.  I had a neighbor throw out a 42" flatscreen.  I passed on that one (with regret) because I'm out of room.

[rr100]

I fully agree with the previous posters: just using what people/companies/schools throw out will give parts to play for a lifetime.

Just one thing I don't see mentioned here: just skip the DMM. When budget is really tight you don't need a Fluke. Yes, a more expensive DMM is maybe faster, nicer, more accurate, safer, etc but in the end you won't get much from it. You might need MORE multimeters (as in you need to use multiple ones at the same time) and many people use this opportunity to have an upgrade but on the other hand many people in the western world would get in their bank account (at least) a 4-digit salary at the end of the month...  So if the funds are tight even if you want the second one get a 3-5$ ebay cheapie (or similar) if it does what you want. I assume you don't work with really high energy circuits and even probing mains now and then with your Radio Shack should be safe (for some definitions of safe) assuming you know what you're doing (use the right range, don't forget the cables/range set to amps, keep your meter/cables as far away from you as possible - not in your lap, treat it like a bomb that might explode, face away from it while sticking the probes in, etc, etc). For other (low voltage+energy) uses the cheapies are perfectly fine as most tasks don't need fantastic precision; just check now and then if they do the right stuff, test something like AA battery, 5V, 12V, a couple known resistors.

[jaqie]

Thank you both for your awesome advice! 

I said before  that I used to want to be an electrician, I know that part quite well, as well as the dangers of putting my meter on the wrong setting before testing house power - I have never once blown a meter in my life, I am very much the careful type... but any electrician that says they have never felt line voltage due to touching something by mistake is a big fat liar, and I have felt that (mostly during childhood when I was learning this stuff) plenty of times.  The RS meter is actually fairly good for it's price, I took some inside pics and will post them in the multimeter thread soon.

Knowing what I know now thanks to you, I may try to find a broken fluke for a steal somewhere, et cetra, though I think I really do need that rigol and/or an olde 20MHz analogue to start this stuff.  I have like 10 LCD monitors with various problems to troubleshoot just waiting for an oscope and about a bajillion other things I wanna try / learn once I get one.

I would NOT buy one of those craptastic meters, I believe deeply as Dave does, that they just aren't worth the hassle and danger... this is why I have this RS meter, it's the best I could afford and it has been golden good to me over the years.  This is prolly the cheapest built meter I will ever voluntarily use.

Old printers... jeez that takes me back.  I have had so many old ones over the years... I think my favorite was a double wide carriage 24 pin 4 color dot matrix printer that came out of an old datacenter.  I used it for like 8 years as my main printer.  Right now I have an HP P2015dn with one extra sheet tray, and I adore it.  Got it for $30 used, i'ts printed under 5000 pages in it's lifetime 

Lesee, on topic... I think I will look for old bench stuff like Dave has, now that you folks have given me the clue-by-four I needed to see that's what I should do is deal-scrounge on old and outmoded stuff, that is what I'll do.  I still wanna build my own power supplies, though.

[cwalex]

I know you never asked this question but I thought I would put it out there anyway incase it helps you or others.

When I start a simple project like guitar effect or headphone amp or whatever and I'm looking for components on element14 or digikey look at the price breakdown for buying quantities like 100 because you might find that it is only double the price of buying the amount you need for the project. If you do this each time you do a project you end up with a nice stock of quality components (with data sheets) that you can use in other projects without having to go to the hassle of ordering parts or at least your parts order will be less next time it beats buying those large resistor assortment kits of questionable quality from ebay and the like.

cheers,

Alex

[jaqie]

Very good advice!  I was just thinking about that sort of thing this morning, actually.

Thank you!

[poorchava]

Power supply is relatively easy to build, once you have bulky stuff. You can scavenge some powerful 12VAC mains transformers from decommisioned halogen lighting. You can also find 24VAC ones for cheap as this voltage is often used as 'safe' voltage in industrial systems.

Power semiconductors can be found rather cheaply. I would start with old audio equipment. Those people are purists and you can expect prime quality components: caps, power transistors, diode bridge. You may even find high quality binding posts, which are useful but normally would be expensive.

I typically rip all the capacitors from every hardware i happen to disassemble. Most modern equipment contains some low-esr mains-rated caps, but those are too bulky for bench psu output filtering. On thwe other hand on the output of switch mode supplies there are also some filtering caps, and those are quite useful (u can use mains filtering caps to build a coilgun if that's your thing )

You can build a simple signal generator around XR2206 (not very expensive chip). On the other hand you can get a DDS breakout board from ebay for ~$10, but that needs a microcontroller to drive it. On the other hand XR2206 won't go higher than maybe 500kHZ, and the DDS module will go above 10MHz probably.

If you want to fiddle around with digital stuff, i would recommend to get a BusPirate (google it). It is a tremendous help when hacking digital stuff. You cang et those from seeedstudio. You can also look at OpenBench Logic Sniffer.

As you are probably gonna scavenge alot, you may want to get a hot air soldering gun. You can either get a cheap one for ~$50 or you can get a construction-grade heat gun which is same as good but less precise (doesn't matter when desoldering parts from scrap).

You can also try getting some broken inverter-type metalworking equipment (mma/mig/tig welders, plasma torches and the like). They will have some fried parts inside (when they break, they typically do so in quite audio-visual way) but you will also find some really high spec parts like high current ultra-fast diodes, IGBTs (not likely, usually they are blown), pulse caps, current shunts, beefy SMPS transformers and the like.

If you have a chance you can dismantle copiers, printers etc. You will be especially interested in industrial/proffesional grade, because they contain quality components. You can often find stepper motors with drivers, working power supplies and huge amounts of precision mechanical parts. Stepper motors can be sold for profit on ebay and mechanics you can stash, as they will come in handy at some point.

If you want to keep your costs low, then you can etch your own PCBs. You will need a plastic tank to store etchant, a laser printer (the older, the better) and cloth iron or cheep document laminator. You will also need a precision drill, but harbor freight-grade dremel-lookalike for $15 will do.

[jaqie]

I am really grateful for your post, but I do not feel well enough to reply in depth right now, sorry... I'll respond in detail when I feel better... thank you and sorry!

[poorchava]

I forgot one thing: if those things are doable or not depends on your disability. I mean for example if you had crippled leg it could be hard for you to dive a dumpster (in a literal meaning). If that was something with your back then you would probably have problem with scavenging heavy stuff. If you're tied to a wheelchair then any scrap hunt may be impossible. It depends greatly.

[SLJ]

I work on mostly vintage equipment now but in the early 1980s when I was first setting up a real workbench and shop I was pretty limited at what I could spend.  Fortunately there was a machine shop at work that I could use after hours to mill blank cases.  For digital work I started out with a breadboard like recommended in the previous posts.  Using that I built +/- adjustable power supplies, a +5V supply, a small digital meter, an adjustable 555 clocking circuit, and logic displays. I wound up putting them all together in this breadboard case (left).

 

That worked out well and I went on and built a matching function generator (right) from scratch.

Since then I have found many pieces of vintage used equipment which I have repaired or rebuilt for use on my bench. 
I don't do much digital work now as I'm into collecting antique test equipment but the breadboard and generator still come in handy on occasion.

[jaqie]

Power supply is relatively easy to build, once you have bulky stuff. You can scavenge some powerful 12VAC mains transformers from decommisioned halogen lighting. You can also find 24VAC ones for cheap as this voltage is often used as 'safe' voltage in industrial systems.

Very good ideas, thanks!

Power semiconductors can be found rather cheaply. I would start with old audio equipment. Those people are purists and you can expect prime quality components: caps, power transistors, diode bridge. You may even find high quality binding posts, which are useful but normally would be expensive.

How I know this... I am one myself on a budget, that is.

I typically rip all the capacitors from every hardware i happen to disassemble. Most modern equipment contains some low-esr mains-rated caps, but those are too bulky for bench psu output filtering. On thwe other hand on the output of switch mode supplies there are also some filtering caps, and those are quite useful (u can use mains filtering caps to build a coilgun if that's your thing )

Yeah, they tend to be low rating when they are that high voltage.  I tend to keep the good ATX PSUs in working condition for my computer hobby, though, so no spare parts there.  The cheap ones... would you want to use the caps out of a psu you don't trust in a project? Me either.

You can build a simple signal generator around XR2206 (not very expensive chip). On the other hand you can get a DDS breakout board from ebay for ~$10, but that needs a microcontroller to drive it. On the other hand XR2206 won't go higher than maybe 500kHZ, and the DDS module will go above 10MHz probably.

Definitely something for me to keep in mind for the long term then.

If you want to fiddle around with digital stuff, i would recommend to get a BusPirate (google it). It is a tremendous help when hacking digital stuff. You cang et those from seeedstudio. You can also look at OpenBench Logic Sniffer.

I already know the buspirate well, from videos and such that is.  I have an FTDI friend from adafruit which I used to unbrick a seagate 7200.11 drive with instructions from the net.  I would definitely want the two things you said!

As you are probably gonna scavenge alot, you may want to get a hot air soldering gun. You can either get a cheap one for ~$50 or you can get a construction-grade heat gun which is same as good but less precise (doesn't matter when desoldering parts from scrap).

I was considering trying to build my own, not sure I can but it would be worth trying I think.

You can also try getting some broken inverter-type metalworking equipment (mma/mig/tig welders, plasma torches and the like). They will have some fried parts inside (when they break, they typically do so in quite audio-visual way) but you will also find some really high spec parts like high current ultra-fast diodes, IGBTs (not likely, usually they are blown), pulse caps, current shunts, beefy SMPS transformers and the like.

That would probably be a good idea, but that is getting too bulky for me to mess around with.

If you have a chance you can dismantle copiers, printers etc. You will be especially interested in industrial/proffesional grade, because they contain quality components. You can often find stepper motors with drivers, working power supplies and huge amounts of precision mechanical parts. Stepper motors can be sold for profit on ebay and mechanics you can stash, as they will come in handy at some point.

Yeah, I tend to dig into that stuff, I should salvage more in the future from them.

If you want to keep your costs low, then you can etch your own PCBs. You will need a plastic tank to store etchant, a laser printer (the older, the better) and cloth iron or cheep document laminator. You will also need a precision drill, but harbor freight-grade dremel-lookalike for $15 will do.

I actually already have a dremel 400xpr I bought in a kit for $50, been a godsend for working on computer mods!  I also have a rather new laser printer, but I can get a used one cheaply if it suits my needs.  I'm a little leery about etching my own PCBs chemically, I have become very sensitive to a lot of chemicals as I became disabled.

I forgot one thing: if those things are doable or not depends on your disability. I mean for example if you had crippled leg it could be hard for you to dive a dumpster (in a literal meaning). If that was something with your back then you would probably have problem with scavenging heavy stuff. If you're tied to a wheelchair then any scrap hunt may be impossible. It depends greatly.

I have two forms of arthritis and a neurological condition, causing me to be in a wheelchair but able to walk for short periods when I brace myself against something.  I don't really get into dumpsters but I can rummage over the side of some of them.  I tend to look and pick a few things now and again when I get the chance, but that's hard since we have a 1991 ford probe and it has to carry around my wheelchair and me and my roomie since I don't drive anymore.  Groceries for the month are...interesting adventures.

Thank you very much for all of the advice!

[jaqie]

I work on mostly vintage equipment now but in the early 1980s when I was first setting up a real workbench and shop I was pretty limited at what I could spend.  Fortunately there was a machine shop at work that I could use after hours to mill blank cases.  For digital work I started out with a breadboard like recommended in the previous posts.  Using that I built +/- adjustable power supplies, a +5V supply, a small digital meter, an adjustable 555 clocking circuit, and logic displays. I wound up putting them all together in this breadboard case.

That looks awesome!  I would personally want to keep some things discrete so I could use them easily with other things and also so I could move one breadboard aside to work on another circuit for a while, but integrating some things into a breadboard like DC plugs and a few LEDs sounds like a very good idea!

That worked out well and I went on and built a matching function generator from scratch.

Since then I have found many pieces of vintage used equipment which I have repaired or rebuilt for use on my bench. 
I don't do much digital work now as I'm into collecting antique test equipment but the breadboard and generator still come in handy on occasion.

I definitely would eventually wanna make my own function gen, and that looks quite nice!  I will almost certainly be collecting inexpensively priced outmoded bench equipment in the coming months, not as vintage as what you seem to have though.

[PA4TIM]

Nice made breadboard. I altered mine too, put a bnc on it with RG179 ending in 2 pins, a powerconnectir and on/of switch. And some bananabusses. But most tings i irst build on copperclad dead bug style.

My first instruments were a 10 MHz scope I bought for a few euro and a Fluke 77 I found on a dirt road in the rain. I then build a L meter, a transistor tester, a signalgenerator, a audio sinewave generator, a squarewave generator.
Then I started collecting old meaurement gear, mostly the non-working onces. Not because of the money in my case, but because I'm sort of addicted to repairing. But if it is not working it is often for free ( I'm a Ham so that makes it more easy, a lot of old Hams have a surplus of gear that once was put aside for repair " someday" )

I also get all the defect stuff from friends and family. In the beginning I stripped everything but now I only take he interesting parts. For instance from computer PSUs I use things like diodes, MOSFETs, fuses, big resistors, heatsincs, fans ect. From other stuf i re-use transformers, switches, busses, conectors, cabinets, sometimes ICs, most times power transistors, FETs, big non electrolytic caps, ect.

I you have the knowledge you can make a lot. I made things like ESR meters ( own design) , femtoFarad meter, spectrum analyser, network analyser, admittance bridge and severl other bridges, Vrefs, signal generators upto 2GHz, counter , coil saturation tester, dynmic load, several power supplys, A 6,5 digit digital volt meter with dual slope ADC but that was just an experiment and limmited to 5VDC, a diodetester, fettester, curvetracer, componenttester, probes ( current, EH, high Z, high voltage) ect. Some to use, others as eperiment.

Often more for the fun of building and as a sort of keep busy therapy because I'm dissabled too.

[poorchava]

I actually already have a dremel 400xpr I bought in a kit for $50, been a godsend for working on computer mods!  I also have a rather new laser printer, but I can get a used one cheaply if it suits my needs.  I'm a little leery about etching my own PCBs chemically, I have become very sensitive to a lot of chemicals as I became disabled.

I recommended an old printer not because it gets abused in the process or something, but rather because of the toner saving techniques they employ. When doing toner-transfer pcbs you want your pritner to deposit as much toner as possible to avoid etchant ingress and dissolving the copper areas which you do not want dissolved.

As for the chemicals themselves, they are not very dangerous. There are three kinds of etchants typically used for DIY: sodium persulfate, ferric (III) chloride and peroxide/hydrochloric (also knows as cupric chloride method) acid mix. H2O2/HCl mix involves nasty chemicals and released chlorine gas which means it requires well ventilated place. Ferric chloride is quite nasty, not because is is particularily aggressive, but because it leaves nasty unremovable stains on anything it touches. Besides this it's opaque and makes it hard to observe the progress of etching. Sodium Persulfate is the most friendly of all those. It does not release fumes, it does not stain. If it spills on your clothes you can avoid damage to them by rinsing those with alot of water (immediately). It also underetches the least of all three. also it isn't very aggressive. You can put your hand into it and nothing will happen if you just wash your hands right after doing whatever it is you're doing.

As for desoldering stuff from PCBs there is also one more method, but rather extreme. You need to remove anything sensitive to heat before (plastic frames, connectors, maybe electrolytics) and then put whole PCB into oven. When you notice solder flowing, wait a little bit more, take the pcb out from the oven with thermoisolating gloves or pliers and slam it a few times against a flat surface. That's actually the best way of desoldering power devices (like a D2PAK mosfets in an inverter, which are soldered to huge solid copper plane(s)).

[olsenn]

It's never a good idea to build something that you can't test. Always have professional, calibrated equipment test the accuracy of your own test gear, and never assume a better accuracy of your test gear than the test gear that was used to test it!

[babysitter]

I suggest you to look out for the local ham radio club. Chances are high that you can get help there, either the chance to ask specific questions someone might answer but also access to the junk boxes of some of the guys/gals there, and maybe bring home some boat anchor sized equipment eventually. Also no ham would mind if you ask to help you out in cases where you need better equipment to verify that your home-made or repaired stuff works as expected.

[Radio Tech]

I suggest you to look out for the local ham radio club. Chances are high that you can get help there, either the chance to ask specific questions someone might answer but also access to the junk boxes of some of the guys/gals there, and maybe bring home some boat anchor sized equipment eventually. Also no ham would mind if you ask to help you out in cases where you need better equipment to verify that your home-made or repaired stuff works as expected.

That is pretty good advice. Hams are always willing to help. I have been in radio and shortwave since I was 11 and in ham radio since the 90's.  We always have stuff in our junk boxes. I recently gave away a 500 MHz frequency counter and a signal generator to a young lad a few weeks back. Never know what you can find just by asking.

Also ham fest are a great place to score some equipment. You have to get there early though. During the day it more of ebay prices.  I picked up a HotVac 2000 model 2000a desoldering station last year for 15 bucks. Works like a champ.  So everytime someone throws something out I grab it, bring it home, and start removing all parts and then recycle the rest.

I also have never bought new test equipment but twice. An IRF1200s many years ago and now a new Oscilloscope. Most of what I buy is non working and repaired myself. Same goes with all my ham radio equipment

[c4757p]

I recently gave away a 500 mhz frequency counter and a signal generator to a young lad a few weeks back.

Sorry to interrupt, but you just stabbed me in the eye with a massive pet peeve! A 500 mHz frequency counter is a guy counting pulses while looking at his watch. That's a 500 MHz frequency counter!

(Sorry to be a pain, but I really, really hate that one.)