My first Scope!

[dj_ricoh]

For many Year i was thinking like this because of $:

Dear Santa Claus...

Recently i manage to help a friend with no intention of getting something in return. After a few days he call me to meet because he got something for me.

When i arrive and he gave me this i swear i was like a stupid kid who got a present from santa! LOL

So!

I have no clue how to work with a scope and i always wanted because in some Notebook cases its kinda interesting how some faults shows up.

I do want to understand more about that the design of the motherboard but the army of engineers who made that board, manage to rise up the level so a ordinary persone without a shop or tools from a shop won`t understand or troubleshoot it.

I came to a conclusion that a scope its a must for a few stage of troubleshooting or understand of "How it works".

I will carry it with for a few week in my bag just in case a get a notebook and its working and i have the chance to something on it like BIOS, Crystal and my fav i wanna see if i can see something related to keyboard signal(can you?)

So... i wanna ask: Your first scope was?

[vinceroger69]

Re: My first Scope!

heres a good manual i came across they look a nice scope for the price i havnt got one yet as saving for hot air station first.

[dj_ricoh]

Re: My first Scope!

[eccerr0r]

Re: My first Scope!

My first scope was a 4" tube (as in, vacuum tube amplifiers and sweep oscillator) scope that my dad got... A second one was another "portable" 2" tube scope. Neither of these two scopes I used much because I really wasn't sure what to use them for...

Both of these were single channel.

The first scope I had and really used was the Vu-Data PS940, a dual channel solid state/CRT unit.

I've been thinking about getting a newer 100MHz scope. However can't really justify the price...

[SteveNielsen]

Re: My first Scope!

Yeah me too, a CRT scope would be nice but I can't afford one either. I could've snagged two older scopes (don't recall the bandwidth but wasn't that high) in perfect condition that were destined for the surplus auction pile but I decided to be an honest man.

[ben7]

Re: My first Scope!

Only thing about some old analog scopes is that they can't store a waveform, I.E. triggering and then continually displaying the waveform from when it triggered, so you can inspect the waveform. Inspecting for things such as spikes, non-linearity, oscillations, etc...

However there ARE older 'analog' (digital waveform storage, with 'analog' CRT display) storage scopes though.

I have a rigol digital scope. My first (and only, so far) scope.

[SteveNielsen]

Re: My first Scope!

That's why someone integrated a Polaroid camera to take snapshots of the scope screen back in the day. Things sure have changed a lot.

[tom66]

Re: My first Scope!

It's an OK instrument for audio use but for most use, you would be better served by an analog scope. You might even be able to get a storage scope for less. The screen is very limited on those Velleman scopes, and there's only one channel.

[stj]

Re: My first Scope!

go to car-boot sales & radio-rally's
you often get people selling scopes & stuff there.

i picked up a relativly modern 100Mhz triple-trace scope with a fault on it for £25 at one a few years ago.

[ben7]

Re: My first Scope!

That's why someone integrated a Polaroid camera to take snapshots of the scope screen back in the day. Things sure have changed a lot.

Hah! How clever!

[eccerr0r]

Re: My first Scope!

It's actually kind of funny, in the "olden" times you do things over and over again and having an analog scope retrigger, and you could see the waveform just fine. However now in the digital age where 1-shots are very common, the trick doesn't work anymore.

I really would like the higher bandwidth of a 100MHz scope but don't think I'd use it way too often anyway. My Vu-Data is only like 20MHz bandwidth but the major complaint I have is that the controls are dirty... sometimes just won't select the right function.

Also another thing I was shocked that it didn't have is XY(Z) mode. So it can't be used to do lissajous curves or raster scanning. Boo. It does have an external trigger that would control the sweep so that's actually a plus.

I don't recall if the two longest owned tube scopes could do XY(Z), but a third vacuum tube scope I have that's got a "huge" 5" CRT (Eico 460) and could do XYZ raster scans and thus lissajous curves.

I heard one feature of the 460 is that its screen ring was the exact size as some common photographic equipment of the era...

[gearhead63]

Re: My first Scope!

I have several scopes, my first was a Telequipment D54-10Mhz that I got off eBay for $50.It actually works perfect and is calibrated.
I have 3 Tektronix (454a,475,2337),3 HP (1740A,1725,1720A) and a Phillips PM3212-25Mhz that I got for $45 including shipping.
I use my webcam on a tripod if I need to have pics or vid for later reference.
I use the Phillips for general stuff, to monitor the output from my Sig Gen, output from an amp, and use my others for more detailed things. Wouldn't mind a digital, but the older analog units can do some things a digital can't and digital what analog can't.
I work mostly with audio equipment, and some test gear, so i have pretty much what I need for now..
If you watch eBay closely you can find some deals, but look close at the feedback of the seller.

[Kiriakos GR]

Re: My first Scope!

I really would like the higher bandwidth of a 100MHz scope but don't think I'd use it way too often anyway.

It is true that when shopping for an Oscilloscope it is hard to predict the ultimate bandwidth that you will even need.

But if you watch the bandwidth specifications of active Oscilloscope probes, you will get a good indication regarding the max usable bandwidth by real applications today.

Some one required an differential probe at 100MHz and the manufactures responded to this new requirement in bandwidth.
Everything is action and reaction.

.

[eccerr0r]

Re: My first Scope!

The main reason being for not having purchased one by now is that a lot of modern equipment are simply unrepairable, or rather need specialty tools to debug and specialty replacement parts that may be hard to get. Also the fact that I'm not in the repair business, this is purely as a hobby making this a "disposable" expense...

I only got my analog scope because it was cheap, and the "disposable" is acceptable.

[Kiriakos GR]

Re: My first Scope!

In this case some one other than you will benefit from my answer.

[rievax_60]

Re: My first Scope!

Not my first CRO, I recently took a chance on an old HP DSO model like this,
http://www.ebay.com.au/itm/Hp-Oscill...-/111221628564
It worked well for a few months then developed a bootup freezing problem.
At the risk of throwing good money after bad, I bought another one. It worked for a while, then Its power supply failed.
I eventually got them both working. The original needed an EPROM transplant.
The 2nd one had a high voltage resistor failure.
I just got lucky this time.

[gearhead63]

Re: My first Scope!

Another thing to consider is that a lot of older analog scopes BANDWIDTH IS DESIGNATED as -3b at a specific frequency. My 100Mhz scope will show a trace well beyond 100Mhz although the calibration will off.

[eccerr0r]

Re: My first Scope!

Speaking of overdriving a scope, it's not just the -3dB, it's also the maximum horizontal sweep. For fun I hooked up my 20MHz scope to the output of a CB radio that I was playing with... at the fastest sweep rate I actually could get a trace to show up, but it was too aliased to tell what the waveform is. However it was enough to tell that it was indeed transmitting something.

But yes, the nice thing about analog is that I still could barely make out that the waveform was at least semi-sinusoidal. If the sampling rate of a 20MHz DSO is too low I don't think I could even make out a sine wave if feeding it a 27MHz signal... So I think except for the storage function, a 100MHz analog > (most) 100MHz digital scopes.

Now if I had that 100MHz digital scope in my hands now I could see the CB output just fine...

[eccerr0r]

Re: My first Scope!

I just got a signal generator to play with my analog scope. While the calibration and bandwidth of the signal generator can be of question, it should be 1V P-P output.

35MHz and beyond - 'scope displays NOTHING
30MHz - Barely can discern a 0.2V P-P signal.
20MHz - around 0.37V P-P
10MHz - around 0.67V P-P
5MHz - 0.8V P-P
3.5MHz - 1V P-P

Now what should this 'scope really be rated at?

[Compgeke]

Re: My first Scope!

I would probably guess 20 - 25 MHz.

Could also be that probe as well but not as likely. Those cheap probes really show their poor shielding when you try them out on a bigger 'scope (like a Tek TDS684B).