Hobby Kick-Off Status, One Request - Page 1
Forum section: electronics / beginners

author: jmcmahon
author_rank: Newbie
timestamp: July 03, 2020, 11:21:22 pm
content: My father spent almost his entire career as a bench tech (bio-med) but I never found it in me to take up the hobby until a few years ago when I dovetailed it with my guitar playing. I'm resuming it in earnest after a hiatus and things are going well. My focus is on audio (guitar pedals, amps, etc.), with plans to dabble in simple RF at some point. I'm mostly assembling kits and breadboarding simple example/test circuits at this point, trying to get the basics down well.O-scope: Tektronix 2445 eBay gamble for ~$100 winning bid. Appears to work perfectly except for mild calibration issues on channel 2. It's occurred to me to swap out the ancient caps but I don't want to break it trying to fix a problem that doesn't exist yet. No probes, so I bought CalTest ones.Power: Siglent SPD3303X-E, since given the "upgrade" to X. No issues that weren't PEBKAC, very happy so far (though I haven't pushed it hard).Signal gen: Koolertron DDS 60MHz. Again, I haven't pushed its limits and it's mostly worked fine.I have three annoyances so far. First, efficient parts storage is a pain; I continue to review how people do this looking for something that fits my style. Second, breadboard quality seems to be a total crap shoot. I'm still assessing how annoying I find this and mostly just working around any hiccups.Third, my request. The Koolertron doesn't generate white noise, it generates a noisy signal based on some given fundamental. I'd really like to test audio filters and whatnot in a less kludgy way. I could pipe it from my computer but that feels incredibly clumsy. I've looked at white noise generating circuits but haven't had luck mocking them up, the results are no different from ambient noise and 60 cycle hum. This could easily be more PEBKAC, though. Can any of you fine folks recommend a circuit to create reasonably "true" white noise across the audio spectrum?Thanks for all the info on these boards, hopefully I can shift from lurking to eventually giving back as well.

author: bdunham7
author_rank: Super Contributor
timestamp: July 03, 2020, 11:41:23 pm
content: Breadboards:http://www.assemblyspecialist.com/WebStore/breadboards.htmlScope: Best leave it be until you are ready for a major disassembly project. El-caps are unlikely to cause just a channel 2 problem. You will likely have to so some cleaning and then troubleshooting. When you are ready start a thread in 'Repair'. I have a 2445 as well and I haven't touched it yet. I have enough things that are actually broken.Parts: Good luck. I use a combination of small plastic divider boxes from Harbor Freight and small boxes from Amazon. It all looks like hell and I rarely find anything in less than 10 minutes, so if you do better let me know how.EDIT: White noise etc: Use a computer if you are into audio. It's great to have other tools, but you will never match the versatility of a PC, soundcard and various programs. Start with sigjenny.

author: wizard69
author_rank: Super Contributor
timestamp: July 04, 2020, 01:34:14 am
content: Quote from: jmcmahon on July 03, 2020, 11:21:22 pmThe wisdom of leaving it along depends a bit on the actual caps in the machine. The problem with leaving it alone is that the caps will leak eventually damaging things. I'd inspect the scope right away before putting a cap update off. It might not need it immediately but you should plan to do a cap swap.QuoteNo mention of a multi meter?QuoteThere is no one right answer here and frankly due to the wide array of parts you might have you can't have one solution.QuoteI can't suggest anything circuit wise but I can suggest looking at a couple of online resources. Mr Carlson's Lab on Youtube cover a whole lot of audio repair techniques and even has some custom designed circuits. xraytonyb is anther youtuber that does audio repairs from which you can gleam info. Basically it comes down to having the right tools and knowing those tools limitations. The nice thing about these two guys is that they are not afraid to mix modern equipment with stone-age instruments.QuoteLurk as much as you want or need. You never stop learning and frankly I see something new to me almost every week someplace on the net.

author: jmcmahon
author_rank: Newbie
timestamp: July 04, 2020, 02:08:16 am
content: I got my multimeter and soldering station a while back, so I tend to mentally back-burner them relative to my new toys.Weller WES51: The knob predecessor to the current digital display Weller. It's treated me very well, much better than I've treated its standard tip, which I need to replace. It was a real revelation getting a fat chisel tip for desoldering, esp. for the backs of pots and other items that suck up heat like MAD.Fluke 115: My only complaint about this is it doesn't come with grabber hook tips, which aren't as cheap as I assumed they'd be. The DMM probably cost more than I needed to pay but hopefully it will hold up like a champ. And I gotta say, I was biased by seeing those fancy yellow gadgets on my dad's workbench.Actually that's a question I had in the back of my mind: for basic, typical bench work, is there any advantage to a bench-top multimeter? Or do those only come into their own in more demanding and precise tasks? When would someone pick a bench unit over a handheld? At some point I'll get a second DMM and assumed I'd get some well-reviewed and basic handheld, but I should at least ask the question.

author: Shock
author_rank: Super Contributor
timestamp: July 04, 2020, 06:24:39 am
content: I personally don't like parts bins as they clutter up the place and are space inefficient and expensive. Just use a set of drawers, secondhand is fine. Each draw being at least a couple of inches deep. If you find some cheap plastic containers you can store parts cassette stye or just use dividers and leave them in anti static bags. The upshot is you can use the drawers for anything, and keep everything tidy and modular.Something like this for parts, tools, adapters, spare multimeters, power adapters, leads on the side. The storage density you can fit into something like this is unbeatable.

author: rdl
author_rank: Super Contributor
timestamp: July 04, 2020, 06:51:02 am
content: There's many options for storing stuff, but one suggestion - if you end up buying a lot of parts from Digikey/Mouser/Newark whatever, I've found it best to leave them in the supplier's packaging. I store mine in plastic boxes (I use Sterilite Clearview 1753 15 qt size with latches, good for storing lots of stuff).

author: gcewing
author_rank: Regular Contributor
timestamp: July 04, 2020, 07:13:30 am
content: For resistors and small capacitors I'm currently using a collection of ziploc bags. Each bag has a piece of paper slipped inside it, cut to fit the bag and printed along the top with a component value in a large font; this serves to both label the bag and stiffen it. The bags stand upright in a tall narrow plastic box, with cardboard dividers between decades of values. This system seems to be working well so far.I got the box from Storage Box in Christchurch, and ordered the bags from packagingonline. If I remember rightly I got a box of 1000 bags for about NZ$16 -- far more than I ever expect to use!

author: Jan Audio
author_rank: Frequent Contributor
timestamp: July 05, 2020, 03:39:29 pm
content: You can make a noise-generator with a transistor + opamp, very easy.First you need to take all (0volt) from one central point in your breadboard, behind the big input cap.Then you need to take a resistor to a elko, from there you take the power to your noise-generator,noise generator runs perfect on 9 volt, so if you have 12 volt, you take this first resistor higher value, so you measure at the elko around more then 9volt for optimal noise.If you have all this you have loud noise and no hum.This solves your noise and breadboard problems for small circuits.For bigger circuits you need to solder them with pin headers and plug into your breadboard.Solder the finished part with pin headers ( no hum or breadboard quality ), and make more circuits in the free space.Finally your breadboard will be full of cards with almost no space left, else you have big problems on a breadboard.For part storage i use alot of these ( bigger and smaller ) screwed onto a wood panel attatched to the wall in my storage place :

author: dbctronic
author_rank: Regular Contributor
timestamp: July 05, 2020, 05:51:58 pm
content: Yes, I also use plastic parts bins, and put small parts in small ziploc bags. You can get these in 1x1, 1x2, and 2x3 inch sizes in the crafts section of Walmart or other suppliers, and are probably also popular with stamp collectors, coin collectors, and the like. They're cheap, and as indicated above, a slip of paper inside, or marked with magic marker outside, works. Leave itty bitty SMDs in whatever carriers they come with, as much as possible. I don't have much complaint with this system - it keeps hundreds of resistors readily findable for one or two dollars' worth of bags. Through hole resistors come in tape reel cutoffs, which go right in the bag neat as can be.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: July 05, 2020, 06:22:46 pm
content: Quote from: jmcmahon on July 03, 2020, 11:21:22 pmI sorted small parts in folders with slipcase, using plastic molded boxes, compare Weltron 902100. There are various topics here about it likethis one. For SMD parts you can also file them in sheets intended for 35mm film or business cards.For the bench multimeter, i use it preferrably because it is most unlikely taken somewhere else, test leads always ready to use, never empty batteries.

author: robca
author_rank: Frequent Contributor
timestamp: July 05, 2020, 08:55:45 pm
content: I second what other people said, a PC with a good soundcard is one of the best signal generators for audio signals, since it's super easy to generate complex signals, sweeps, left/right balance, etcI recently discovered Daqarta, which is incredibly powerfulhttp://www.daqarta.com/dw_gen.htmfor anything in the audio rangeAlso, a USB microphone like the Umik-1https://www.minidsp.com/products/acoustic-measurement/umik-1(which comes with calibration data) and REWhttps://www.roomeqwizard.com/allow you to test pretty much every audio component, from amplifiers to speakers (I used that combination when I assembled my DIY speakers)

author: wizard69
author_rank: Super Contributor
timestamp: July 05, 2020, 10:54:57 pm
content: Quote from: jmcmahon on July 04, 2020, 02:08:16 amFluke makes excellent handheld meters, you should have a good long term relationship with the meter. As for test leads do yourself a favor and inspect and replace them regularly. This especially if you work around any high voltage. I may be biased here working in industry, where the systems I'm exposed to are 600 Volts or less, but safety should never be ignored. If you don't have the right probes for something you intend to do buy them!!!QuoteThis is the easy one to answer. There are two big advantages and possible a few minor ones:The display is easy to see and the meters don't tip over on the bench. This is number one on the list and I'm serious, a big advantage to a bench meter is ergonomics.The display can be on all day, you don't have the meter going into power savings at the wrong time. Again this amounts to an ergonomics issue.4 wire ohms can be a very handy thing to have.More resolution on the display. I have mixed feelings about this because you can do an awful lot of diagnostic work with a 4.5 digit meter. So I don't consider this a big deal for most repair benches.Some sort of computer hook up. Again not so hot on a repair bench but more important if you are developing certain sorts of circuits.Possibly higher accuracy (many handhelds are really good these days) and great stability.If You get into electronics deeply, you will find that you need more than one meter anyways so having a good bench meter is a very good idea. It can be used to verify the operation of cheaper meters.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: July 06, 2020, 01:45:00 pm
content: So funny, you advice to hook up a computer while you only need 2 transistors.

author: robca
author_rank: Frequent Contributor
timestamp: July 06, 2020, 04:13:08 pm
content: Quote from: Jan Audio on July 06, 2020, 01:45:00 pmIt really depends on what the OP wants to do. If all he needs is white noise, sure, two transistors are ok. If on the other hand he wants to "I'd really like to test audio filters and whatnot in a less kludgy way", white noise is not enough. You need sweeps (linear, logarithmic) at different frequencies, impulse response, etc. All things that REW is designed to do (and free)Not to mention that we all have a computer handy anywayright now, it would be easier for me to use my laptop to generate white noise than dig into my loose parts bins, find all the components I need, solder them and connect to a power supply. Then discover I need pink noise instead, and redesign it

author: Jan Audio
author_rank: Frequent Contributor
timestamp: July 06, 2020, 04:27:17 pm
content: I am more like : anything that works is welcome.If it gives sound i want it.I bet the starter also.

author: themadhippy
author_rank: Super Contributor
timestamp: July 06, 2020, 04:35:00 pm
content: for white noise go old skool and use an untuned radio

author: jmcmahon
author_rank: Newbie
timestamp: July 06, 2020, 08:47:43 pm
content: Versatility is good, so computer-based options are always good to know about. I have my previous PC on my workbench, it's still got way more than enough horsepower for electronics-related mucking around (LTspice, my DAW, etc.). Also thanks for the Daqarta info. At this point I'll also continue to pursue a dedicated external white noise circuit just out of spite. Spite is a handy learning tool.I'll mentally file away these storage ideas with the preexisting ones from the forums. My current paradigm isn't unusable, just sub-optimal.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: July 07, 2020, 02:01:26 pm
content: Connecting your computer is asking for trouble.

author: robca
author_rank: Frequent Contributor
timestamp: July 07, 2020, 03:53:57 pm
content: Quote from: Jan Audio on July 07, 2020, 02:01:26 pmOut of curiosity, what is dangerous about connecting a PC (or a USB audio dongle) to an audio circuit?I'm not suggesting to use a PC as a generic signal generator for higher voltage circuits under test. This is about a way to test audio filters and other audio gear (amplifiers, effects, etc), using an audio signal generated by a PC

author: SilverSolder
author_rank: Super Contributor
timestamp: July 07, 2020, 04:44:27 pm
content: Quote from: robca on July 07, 2020, 03:53:57 pmI use PC generated audio for electronics projects all the time... The biggest issue is ground loops interfering with the signal. You can do many things to mitigate that: use a laptop (on battery power), use a USB isolator, use an audio transformer, etc.Here's a cool thing you can do: download Digilent's "Waveforms" application, the one that comes with the Analog Discovery 2. This app can use a regular sound card... so your PC becomes an (audio frequencies only) oscilloscope, signal generator, maybe spectrum analyzer and VNA too, completely free... (and you can always get an AD2 later if you want to increase performance)!

author: RJSV
author_rank: Super Contributor
timestamp: July 07, 2020, 07:32:17 pm
content: My thoughts regarding my approach to your annoyances:. Try spend time walking around your local AUTO PARTS STORE. You may find a great little multimeter, cheap. Plus the shelves often include several LED accessories, to help you explore simple circuits, where the key is getting a correct LED resistor. Those 'automotive' systems often run fine using a 9 V battery. I built a great diorama, featuring the Paris Tower scene, using a 3-D Hallmark Card from adrugstore.Now, my LED controller doesn't have to literally connect to Red/Green/Blue for a car interior. You can connect for example, a White LED up overhead to the controller RED output and put that up over the diorama. For a dawn lighting effect, you can attach some RED LEDs, and have the controller go thru a dim-to bright sequence. Of course, I tried to put blue up top as a 'sky', and very much enjoyed that art.Ok. Now also I bought 2 lead-acid type batteries plus, again a small 8 by 10 solar panel. Again, that was at the car parts store.For a signal source, I own two 'OLYMPUS' hand held audio recorders. Those stand alone devices can record HOURS of sounds, and feature two speed/pitch changes. Heck, you might try, maybe HISS into the microphone yourself ! (?).Gotta stop here, but lastly see if you can use a sheet music cabinet with many drawers.And pay some attention to your own personal creative process. I stopped drinking beer when trying to kick-start a game coding gig on the C-64 computer.Great, maybe I can help later, as you progress.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: July 07, 2020, 08:00:13 pm
content: This is a mostly a copy of my post to "From No parts to...About storage of parts...If you expect lots of small parts some people store them in loose leaf binders. You can buy the sheets with pockets on e bay. EEVBlog did sell them also I think.But the Significant Other has a better suggestion:Get some plastic sheet protectors(regular office supply) and aWe R Memory Keepers FUSE kit.This is a scrapbook company. The Fuse tips are rotary tips that function like a cutter or plastic welder on a solder gun like handle. Look it up on Google, Plenty of videos. You can make all sorts of different size pockets for SMD type parts. You can make the pockets big enough to contain a readable label. You can have several binders on a shelf, like an encyclopedia of parts. You can make the sleeve fit the part you have. This is kind of like the suggestion of using 35 mm film sheet protectors.This is nice for small parts. Especially a length of SMD parts in their tape.I actually just ordered the roller tips and used a machine tool tap to fit them to an adjustable soldering iron. They screw in.For larger thru hole parts I like old card file boxes (3x5, 4x6 whatever..) with the same size envelopes instead of cards..Get them at Salvation Army for 10 cents... Can use envelopes or tape parts to index cards...If you try to get plastic bin type boxes they will eventually force you out of your house...I already have too many....Advice from others here is good about just getting a assortment of resistors and caps to start with.. however I do not know if you need SMD or thru hole partsWally KC9INK

author: wizard69
author_rank: Super Contributor
timestamp: July 08, 2020, 02:52:20 am
content: For storage of tools one thing to consider is machinist type tool boxes. Specifically not the mechanics boxes you can get everywhere. These have a number of thinner drawers better suited to the types of tools use on an electronics repair bench.On the flip side a mechanics roll around, especially if gotten used, can be an excellent poor mans Vidmar. You then populate the drawers with bins fromhttps://www.schallercorporation.com/or other similar suppliers. Obviously not so good for SMD components like resistors and caps but great for the larger electro-mechanical items that are part of the hobby. The thing is mechanics tool boxes can often be had for a song on the used market. More importantly they have wheels which means they can be parked out of the way and even pass as work tables when needed.I have a mixed use work shop (best way to describe it) and I've learned the hard way (old age has something to do with it) that tools, tables and machines on wheels are a good thing in many cases.

author: Jan Audio
author_rank: Frequent Contributor
timestamp: July 08, 2020, 01:57:24 pm
content: Quote from: robca on July 07, 2020, 03:53:57 pmAll computers are different, some might have no problems.It is a complex machine with all sorts of digital stuff going on including USB.If you use some USB thing it might be good i dont know about modern stuff.And maybe real sound-cards dont exist no more.Still i would not advice to connect a computer.What is so dangerous ?, i dont know.You working with much amplification you gonna hear things.Breadboard is already bad enough itself, i always had problems with computers.

author: dbctronic
author_rank: Regular Contributor
timestamp: July 08, 2020, 06:57:04 pm
content: @Wizard69:I too have a mixed use shop - work benches, table saws, radial arm saws, planer, all on lockable wheels. My 'tronics area is still just a bench top with some shelving and freestanding piles of stuff nearby, but it gets me through. If I reach the point where I think my soldering iron and multimeters need wheels, I'm switching to matchbook collecting.