First oscilloscope, first set of probes now what? - Page 1
Forum section: electronics / beginners

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 13, 2014, 11:33:59 pm
content: I just got my first scope, it's an old analog, 2-channel, seems to be fine but what do I know.Here's what I've done so far:Before powering on I set the knobs per the manual.Powered it up, said ooh and ahhh.Found the beam!Saw that I could read DC 5 volts on each channel!!The beam is nice and bright and straight at DC 5V!!(hard to tell but it was exciting)Now what? I placed the probe on my finger tip. EKG???I think it was picking up 60Hz on the probe cable but don't know.I found the 500ms pp, 1kHz probe compensation port, found the small screwdriver and adjusted the probes on each channel(thanks to w2aew)So I think the scope's okay, but what I think's not backed by anecdotal or empirical evidence.It's only what I think and I don't always believe what I think.(does anyone?)What other things can I do to test the scope?How can I create some interesting tests for this scope with what's at hand?My lab consists of a DMM and an oscilloscope and a digital soldering station plus some minor tools.I have a salvaged PS from a dvd player that has DC -12V, 12V, 5V outputs.I have a breadboard and various resistors, transistors, caps, motors, transformers salvaged from a tv/video combo and a dvd player.(I have the solder burns to prove it!)Here are the probes I just got:https://www.eevblog.com/forum/buysellwanted/good-ebay-deal-buy-it-now-scope-probes-$8-99-free-shipping-in-us/I've got a pdf of the manual but it's a pdf of jpg images and the aspect ratio of the images doesn't fit my reader and so I need to convert that which is a PITA.I really need to convert it into text and a proper ebook but that leads me to tesseract and on down the rabbit hole I go.

author: cellularmitosis
author_rank: Unknown
timestamp: February 13, 2014, 11:43:11 pm
content: Hook your probe up to a switch mode power supply. Fiddle around with the settings until you get a nice steady trigger on all that gross noise!If you go down the path of wanting to make low noise measurements, you'll eventually want to buy some spring tips for your probes (reduces the loop area which picks up 60Hz noise).

author: AG6QR
author_rank: Frequent Contributor
timestamp: February 13, 2014, 11:53:42 pm
content: Quote from: GiskardReventlov on February 13, 2014, 11:33:59 pm60Hz means 16.667 mS per cycle. So set your horizontal scale for 10 mS/div, and you should see a bit more than one and a half divisions per cycle, if you're seeing 60Hz AC. You probably are -- 60Hz gets picked up easily when a probe is unconnected.Resist any temptation you might have had to connect the probes directly to AC mains to study the waveform.If you have any battery operated audio devices, radios, CD players, mp3 players, etc., try placing the probe across the speaker output. If it's random audio, and not a pure tone, you'll see oscillations, but they'll vary as the audio varies. You might have to set the trigger to be free-running to see the trace.If you have a computer with a sound card, search the web for "sound card signal generator". You can easily get your computer to generate waveforms at audio frequencies. Quality will depend on your soundcard quality, but it should at least be enough to get some practice using the scope at different frequencies and amplitudes, and you can play with trigger levels to better understand how they work. It should probably allow you to do simple experiments like testing the voltage vs current for various reactive components at various frequencies.

author: edy
author_rank: Super Contributor
timestamp: February 14, 2014, 02:49:40 am
content: Congrats on your first scope. There are a few things to try first for fun.... Hook up to your cellphone or pc audio and find oscillofun or youscope demos on the Web (flac or wave best, not mp3). Set it up in xy mode for those. Also you can find wave generators for pc to generate lissajous patterns. You can also pick up a gabotronics xprotolab to make various different waves.If you want to try programming an arduino with resistor ladders you can make stepped outputs (DAC) to draw stuff. Basic electronic fun would include looking at RC filters, how caps alter your 1k calibration signal, and playing with component tester (if your cro doesn't have one, you can build one fairly easily). The tester simply cycles from -voltage to +voltage across the x while checking component on the y. Then you see led response curves, diode L, and so on. You can use a saw wave generator.I am sure there is a book somewhere with a bunch of easy projects to build just to display and learn on a cro.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 14, 2014, 03:17:51 am
content: Quote from: cellularmitosis on February 13, 2014, 11:43:11 pmI don't have a switch mode PS. But will try to find one locally.QuoteI think the probes have spring tips but not 100% sure what they are, the probes I have come with removable tips that contain a retractable hook that is spring loaded. Are we talking about the same?

author: Rudane
author_rank: Regular Contributor
timestamp: February 14, 2014, 03:25:16 am
content: What's the model? It likely has a test clip for a square wave you can use to adjust the probe compensation.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 14, 2014, 03:41:04 am
content: Quote from: AG6QR on February 13, 2014, 11:53:42 pmThis makes sense. I noticed in videos the 60Hz AC signature. I wasn't able to do much with it, But I will revisit that later.QuoteGood advice and no problem here. I recently blew the 15A breaker probing where no one had probed before. I was testing the mains input on my salvaged power supply. My new DMM probe tips are no longer new looking. The soot is a reminder. Emory cloth restored them from jagged peaks back into a tip albeit a little shorter. It was last the thing I did before calling it a day. Pure stupidity. There I was standing in the dark. Mostly concerned with my new meter of course. Then I started to think about the breaker. It was a new breaker and performed well and isolated the stupidity to the "lab". The meter survived no problem!QuoteThis I can try! I have an old mp3 player that I secretly hope will release it's magic smoke. But it may prove hard as this thing never got the smoke to begin with. It's a Long Duck Dong model.

author: kc9qvl
author_rank: Regular Contributor
timestamp: February 14, 2014, 03:46:58 am
content: Perfect test use a small switch mode power supply(cell phone charger). 1st set scope to dc coupling find the trace. Then do a rise time measurement.After set to ac coupling and check the ripple.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 14, 2014, 04:04:01 am
content: Quote from: kc9qvl on February 14, 2014, 03:46:58 amOk I do have a switch mode power supply. (cellularmitosis I lied) I will try this as well.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 14, 2014, 11:40:46 pm
content: Quote from: AG6QR on February 13, 2014, 11:53:42 pmI took it for granted that I'd figure out what you meant once I got in front of the scope. But I gave it a shot and I only see the 60Hz I'm bathed in here.What does "set the trigger to be free-running " mean?

author: kc9qvl
author_rank: Regular Contributor
timestamp: February 15, 2014, 02:02:08 am
content: He's talking about "auto" mode on triggering. You will always have a trace on the display even if not triggered.Check out alan w2aew's "Scopes for Dopes" videoI've watched it several times.Also give use some pictures of your set up

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 15, 2014, 03:25:20 am
content: Quote from: kc9qvl on February 15, 2014, 02:02:08 amI've watched that once and need to watch it again. The problem I had with it was that questions came in from the local audience which I couldn't hear and then the conversation changed toward that question and I get a bit lost.Yeah I have it on auto mode.I need the "Oscilloscopes for those that like to learn by doing - Step-by-step and hands-on".I'll figure it out, the learning curve's steep but it's easy to keep climbing because I enjoy it.I am converting the manual (PDF-- all small jpg images) into an ebook. I could not bring myself to print out 400 pages.Once I get the ebook on my reader than I can go through the manual and get more familiar in front of the scope.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: February 15, 2014, 04:21:37 am
content: Make this!

author: deth502
author_rank: Frequent Contributor
timestamp: February 15, 2014, 08:23:44 am
content: get yourself a few 741 op amps, theyre pretty well outdated so i cant see them being more than 5-10 cents a piece, and make up a simple wave generator. gives you practice with building circuits and using the scope.http://www.ody.ca/~mgenovy/opcct2.GIFhttp://2.bp.blogspot.com/-jfF6l1z-fBk/UHbhpIRqA4I/AAAAAAAAAN8/0K4Ygc8WkhE/s1600/A%2BSimple%2BFunction%2BGenerator.jpg(teh 1458 is just 2 ganged 741 op amps in one ic)a 555 will work too, another cheap ic.http://www.seekic.com/uploadfile/ic-circuit/2011420212730799.jpg

author: cellularmitosis
author_rank: Unknown
timestamp: February 15, 2014, 09:45:14 am
content: Quote from: GiskardReventlov on February 14, 2014, 03:17:51 amSorry, what I meant was a "ground spring".Start watching at about 0:55They really work!

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 16, 2014, 12:53:53 am
content: Quote from: cellularmitosis on February 15, 2014, 09:45:14 amI see, interesting, I will try that out.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 16, 2014, 12:57:56 am
content: Quote from: timelessbeing on February 15, 2014, 04:21:37 amI haven't looked at the schematic yet but that could be fun.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 16, 2014, 12:59:30 am
content: Quote from: deth502 on February 15, 2014, 08:23:44 amI didn't find any for 5-10 cents but it sounds like an economical project still.

author: edy
author_rank: Super Contributor
timestamp: February 16, 2014, 03:01:33 am
content: Use your 1khz square to drive an RC circuit and display output of both square and modified rc output on both channels. Using calculator here:http://www.pronine.ca/rccir.htmYou will find combinations of RC that give a nice curve in the time required of 1 kHz (about 0.5 ms). R value about 100 ohm with 2 microF, or 1kohm with 200 nF, or try some other combination if you can find standard values for components.

author: sourcedog
author_rank: Newbie
timestamp: February 16, 2014, 02:59:23 pm
content: If I had a scope (still trying to source a not too pricey one), I would build up some 555 timer circuits and fiddle with parameters and watch would happen.

author: Redcat
author_rank: Regular Contributor
timestamp: February 16, 2014, 04:06:57 pm
content: Hi, what oscilloscope model did you get?For testing the scope functions the calibration signal is a good start, you can measure rise time, frequency, amplitude... more or less acurate.I like deth502's first schematic very much, there you have 3 different waveforms to play with.Here is also a nice link to a website about such oscillators:http://www.onegentleman.biz/Hardware%20Design/Op-Amp%20Oscillators/2013-Op-Amp%20Oscillators.php.And here is something nice experiment to play: if you have a little flashing LED candle lightyou could try to hook your probe to it and look whats going on :-).Crack the top part open and hook the ground clip to the negative LED pin and probe the other 2 pins. You will get some square-wave signal (50% duty cycle to save energy) and when you make your timebase slow enough, you will see some dc offsets (spikes) from time to time - this makes the LED flicker.Have fun playing with your oscilloscope :-).

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 16, 2014, 07:29:04 pm
content: Quote from: edy on February 16, 2014, 03:01:33 amBy "drive" you mean to connect the 1kHz output to the external trigger BNC input?Then connect one channel also to the 1kHz square and the other channel to the RC circuit with the probe in series?i.e. probe tip to the RC output and the ground clip to where???I feel a bit clumsy as I usually just try stuff out and see what happens but I don't really want to do any permanent damage to anything.

author: Redcat
author_rank: Regular Contributor
timestamp: February 16, 2014, 08:18:45 pm
content: I think edy is talking of a filter like this:You can build it up on a breadboard and use a variable resistor (and variable cap) to play with the effects it does (low pass/high pass as the name says).Doesn't have anything to do with the trigger input.Ground is for example at the outside of the scopes BNC connectors (sometimes there is also a little ground loop/GND connector at the front, depends on your scope) and the signal is obviously on the scopes test-signal output :-). You could hook the RC circuit to them and the probe and it's GND clip to the output of the circuit (see the bottom line in the schematics as the ground).And you hook the second probe directly to the test-signal output.So you can compare both to each other and vary the resistor and look on the effects the RC circuit does.Asking this questions I would really not recommend you to hook anything of your scope to something like a switch mode PS as it was suggested some comments before (or something other not battery driven), unless u are a little more experienced in using your scope, or you really might damage something (or yourself).There is also a nice (longer) video from w2aew at the top of the Forums beginner-section that can make you a little more familiar with the basic function(s) and components of a scope.Hope this helps :-).

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 16, 2014, 08:20:37 pm
content: Quote from: Redcat on February 16, 2014, 04:06:57 pmIt is a very old Tektronix 2215A, but it seems to be working properly. I have to admit that I don't get attached to inanimate objects to the degree that I see that some do here, but this scope has a certain set of qualities that I like. The knobs are damn fun! I like the time/div knob, it requires a firm purchase and has a feel that I don't recall encountering on any other device. When I first tried to adjust it I thought that I would either break it or it was already broken. But then I discovered it requires force. I hope these new digital scopes retain that feel, if not I don't know if I want one!QuoteI am simlutaneously reading a DC/AC text book, converting the tek manual to an ebook and reading it*, looking for the parts mentioned so far, learning a breadboard (or some call protoboard), learning programming mCs (and what to buy) and putting my "lab" together (which means making space).But I will soon have a chance to follow the schematics mentioned so far and try them and report back.QuoteI think I have such a candle, great ideas! And it is fun isn't it.*Also reading a series starring the Posleen**if they made this into a movie it might disturb the masses.

author: edy
author_rank: Super Contributor
timestamp: February 16, 2014, 09:15:21 pm
content: Yes, attach 1kHz calibration to scope channel 1.Also attach 1kHz cal (split off from channel 1) to an RC filter, like the one shown in a previous post. For channel 2, attach one lead between the R and C and the other after the C as your ground, like the schematic shows. Hopefully this setup won't cause too much interference between the 2 channels.Use R of about 100 ohm with C of 2microF, or if you multiply R by 10 to get 1kohm then divide C by 10 to get 200nF. If in doubt, use a RC time calculator and get something in the range of 0.5msec to get to about 90% rise time.I also agree with a previous comment that if you are not experienced yet, stay away from any mains plugs or power supplies. Stick to battery powered stuff or a breadboard powered by a DC or AC power supply but be sure to figure out how to properly ground, so you don't blow yourself up or your scope.There is a nice video by Dave regarding how ground works on scopes. You want to make sure you don't touch something you shouldn't and ground your high voltage circuit through to earth ground shared with your scope, shorting through your probes.

author: Redcat
author_rank: Regular Contributor
timestamp: February 16, 2014, 09:27:12 pm
content: Guess who has also a nice old 2215A. Good choice. It's a good beginner scope (if you want an old analog scope).Yes the Teks have a different "feel" than other (old) scopes. A lot of plastic knobs. They have nice functionality compared to other and a nice layout. Don't expect this feeling from a modern scope (especially not from cheaper ones).Be careful, the knobs are not as robust as you think. It shouldn't take too much force to rotate them, or they can break (they are over 30 years old now in most cases).You may have discovered that the 2215A has a second time base and you can access it by pulling on the time base knob and rotating to the right. But I would suggest you to download the handbookpdf(you can find it for free on different places, there is a operators manual and a repair manual), to learn more.Try an Arduino to get into MCs, it's an easy way nowdays and you can use it with a breadboard and there are a lot of modules for it availiable.The candle was a quick idea. I had one laying around and always wanted to look at it- did just try.Of course it can't be used anymore as a candle light as I had to cut it open, but it was fun.I was once told, that it is playing music, but instead of a speaker it has an LED. Don't know if it's true.Maybe the scopes load alters the candles output a little.Edit: I have to correct me, the frequency is really altered (between 2kHz and 3kHz at my candle) so could really be high pitch music(could not reproduce the dc offset spikes...hmm).And here is the link to the video edy mentions about grounding ():Have fun :-).

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 17, 2014, 10:34:44 pm
content: @edy great detailed instructions, just what I need, will report back at some point. I will check out that video.@Redcat, good call on treating the knobs carefully. I am converting the pdf manual I found to epub. I'm at the 90% mark but the last 10% will be slow since I want to preserve the graphical elements from the original and I want to rid them of noise from the bad scanning. As for mC I think I will try atmel stuff, simple stuff, cheap stuff.I could not find the candle but I have lots of other things to try.

author: Redcat
author_rank: Regular Contributor
timestamp: February 17, 2014, 11:06:37 pm
content: Yes Atmel. I used them in many projects (ATMega8), and you can get them in all sizes and DIP or SMD. You need basically nothing to make a little MC circuit with them, because there is all build in. Try out Bascom, it's a Basic language which is far more easy than C or ASM for a beginner. When I remember correctly it was for free use up to a 2 kB program (many years ago it was 4kB), more than you need for a little project.The Arduinos use also Atmels.Ok, you have the manual, this is good. The scanning is not so good, I know, but at least we have one (I printed my out and made a book).

author: edy
author_rank: Super Contributor
timestamp: February 18, 2014, 03:29:49 am
content: Here is what I mean about using 1kHz calibration out on channel 1 and then taking a reading off an RC filter for channel 2. Notice that when the RC is not hooked up, you get a clean square on channel 1. As soon as the RC is attached, the square gets messed up although you can see channel 2 is a lot more of a decay/rise time effect.Anyone have any idea how to isolate the square wave more so as not to be influenced by the RC?

author: edy
author_rank: Super Contributor
timestamp: February 18, 2014, 03:53:36 am
content: By the way, I used a 1k Ohm resistor (color code brown-black-red-gold) or 1 0 x10 which is 1000 ohm.And the cap is 104 which means 10 x 10000 or 100000 or 100,000 pF which is 100 nanoF.Plug that into RC time calculator and you get 0.0001 seconds or 0.1 msec to get to 63%, 0.16 msec to get to 80%, and 0.23 msec to get to 90% of my peak voltage. My square is 1kHz freq meaning the high is 1/2000 of a second or 0.5 msec and the low is another 1/2000 or 0.5 msec for a total cycle from peak to peak of 1 msec or 1/1000. So you can see the curve reaches 90% of the height in about half of the square high, and decays the same way.

author: katzohki
author_rank: Frequent Contributor
timestamp: February 18, 2014, 04:10:05 am
content: I agree with what some others say about looking at some audio signals. Go down to the 99 cent store (if you have them in your area) and buy some cheap audio patch cable, or even headphones. Strip them so you can get at the wires and use them to look at audio signals!

author: hamster_nz
author_rank: Super Contributor
timestamp: February 18, 2014, 04:27:38 am
content: Quote from: edy on February 18, 2014, 03:29:49 amThe problem is that their is too much load the calibration output. The output impedance is of the order of maybe 500 Ohm (well on a PicoScope 6400 USB it is 600 ohm),Try using 10k R and scaling the cap to suit.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 18, 2014, 05:28:26 pm
content: @AG6QR, I hooked up my probe to the mp3 player headphone jack but I didn't see anything that look like audio. I see only the 60Hz. I probably did not connect things correctly. Do I need to push the audio through a circuit on the breadboard? I connected the scope probe directly to the headphone wires by clipping the probe tip to one wire and the ground clip to the other.@edy, I'm taking notes and appreciate the detail.@Redcat, are there regular maintenance tasks that are typical for these scopes? What hardware programmer do you use for atmel? What dev. tools do you use? I will have a look at Bascom.@katzohki, yep, had a crap pair of headphones for a cell phone.

author: Redcat
author_rank: Regular Contributor
timestamp: February 18, 2014, 06:46:27 pm
content: Hi GiskardReventlov,As beginner you shouldn't worry too much about the inside of the scope (for calibration or repair you need a little more knowledge and tools), but it is good to always take the front cover on if you don't use it and keep it clean. Not much to do.If you don't use it for longer, there can be some corrosion or bad connection inside the pots/knobs/switches, so you should use it from time to time to keep it working (or at least turn the knobs...this may be the reason why your knobs are a bit stiffy).For the Mega8 I build the programmer cable myself. It was basically a parrallel port (printer...) cable with some resistors in the right places going to the programmig pins of the MC.Very basic but it works. But you can buy a cheap Atmel programmer (or programmer cable). This may be better for your need.I mainly used Bascom and for some software communicating with the MC I used also Delphi (I think the last I have is Delphi 2006) to make some PC software for this .But with a modern windows system and the missing COM and LPT ports on a computer it is nowdays not as easy as it was some years ago.But If you use an Arduino it's easy with the USB connection.For the basic "Hello World" application which is in MC world a blinking LED, you don't need more than the Atmel (ATMega/ATTiny), the programmer (or cable), 9V battery, a voltage regulator (5V - like 7805, and maybe 1 or 2 additional caps - but you don't need), a resistor and the LED and something you mount this (breadboard or PCB). Not many parts - simple made.Could you post an image, how you connected the scope to the cable?That your old headphone cable didn't work may be a problem with the cheap headphone cable and not your fault. I once cut some headphone cable (needed it for some application) but couldn't solder it because it was crap. Problem is, you might not get the GND contact(shielding), only the left and right channel signal line (you need to probe one channel signal and the crocodile clip to the GND, not booth the channels). So there are 3 wires inside for stereo and 2 wires for mono. Try to probethe cable with your DMM, which contact of the plug goes to the end of each wire. My recommendation would be, take a piece of 2 wire cable and a 3.5mm plug and make yourself a cable. Cut an audio patch cable may also be ok (may be of higher quality), but I don't have one to try.The long headphone cable works like an antenna that picks up the 50/60Hz line frequency, thats the reason why you see this signal.Good luck

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 18, 2014, 07:16:27 pm
content: Quote from: Redcat on February 18, 2014, 06:46:27 pmYes the first time I turned the time/div knob it was stiff and since then it turns easier but it's firm and good. Very good force feedback.QuoteThis is what I intend to do.QuoteSimple == Good.QuoteYes, though not much to see, I will test continuity as you recommend and find out what wire connects to what tip.QuoteI understand you, good info, will figure it out.QuoteYes, I do wonder how it effects us to be bathed in this. I think our operational freq. is 8Hz (Scheuman resonance??).

author: Redcat
author_rank: Regular Contributor
timestamp: February 18, 2014, 07:48:17 pm
content: Here are some additional MC links for you to look at:Ok you will buy the programmerbut here is the mentioned link to the programmer cable (in german):http://www.dieelektronikerseite.de/(Image is from this website)Bascom (the demo Version link with 4kB is on the bottom):http://www.mcselec.com/index.php?option=com_docman&task=cat_view&gid=99&Itemid=54There was a very nice Bascom/Atmel beginners workshop website too, i sadly can't find it anymore (this was my favorite MC learning website when I first used MCs like 15 years ago).At university we used much older MCs and ASM, this was a real pain...and the ATMega8 was heaven in comparison.A simple LED project is always good start.As I understand, you don't want to use an Arduino, but there are also some nice other simple Atmel developer platforms availiable, like "MyARV"...Or If you can solder a little (you should lern), build your own board like you want.QuoteI think you will easy work out whats wrong with the cable.Sorry for my english.QuoteYes there is so much electronic stuff around us with all kinds of emission - can't be healthy.

author: katzohki
author_rank: Frequent Contributor
timestamp: February 19, 2014, 07:13:49 pm
content: Did you try playing some MP3 files? You're not going to see anything on the audio jack if it's not playing something.

author: lapm
author_rank: Frequent Contributor
timestamp: February 19, 2014, 07:22:27 pm
content: Some of those cheap headphones uses some sort of super cheap cable. seems to have some sort of coating that makes soldering next to impossible. If i would need to measure audio, i would probably go and get connectors and hook up directly to those..

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 19, 2014, 08:51:27 pm
content: @Redcat, your english is fine, better than my german by lightyears*. I will check those links and myarv. I got an atmega32 to play with and will post something in the other section of this forum later.@lapm, I didn't have to do any soldering, I just pulled off the ear piece and strip the wires*I want to learn german, I will start by learning to swear at electronics in german, won't offend anyone, well unless they understand german

author: edy
author_rank: Super Contributor
timestamp: February 20, 2014, 02:51:02 am
content: You should look for youscope.wav or oscillofun.wav with Google and set your CRO in xy mode. Then just output left to channel 1 and right to channel 2, connecting ground common to ground. Here I did it with my cellphone playing a YouTube version of those demo audio files to an xprotolab:

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: February 22, 2014, 03:58:18 am
content: I've got some 555 and some 741 opamps so will try some of the other suggestions. There's also an interesting circuit w2aew, in the "How much bandwidth do I need" video. I like that circuit because I know exactly what should display on the scope. (Correction: the correct circuit is in the follow up video to this one)I got the right jack and looked at the audio, I then set to "Both" and looked at alt, add and chop with ch.1 on the "probe adjust" point and ch.2 on the audio. That's an interesting thing to see.One of the main reasons for this post was to make sure the scope's working correctly and it seems to be fine. And that's a bit of a relief.I'll report back here again as I progress through the other examples.I had saved an old CRT stand, the kind that clamps on to the table/bench and swivels. This one is really old and built like a brick s**t house. It was designed to hold those old monster 19" crts that weighed 60-70 pounds. It has brass bushings and is simple and I could never get rid of it just because I admired how it was built. It now holds my scope above the bench and swivels and saves bench space! It has u-shaped rod that extends forward so this long scope fits on it perfectly. The u-shaped rod is bent vertically at the outward side so the scope handle rests against that and prevents any sliding. I knew someday I'd find another use for that thing!