Computerized "Scope"

[nickt]

Those are differential probes
http://www.linkinstruments.com/adf25.htm
the standard probes are $80

In reality I only use it for Spectrum stuff
I use a 465B and 2465B as a work horse

Also the DSO 2100 is discontinued and they only offered to pay me $100 for mine to upgrade so maybe they will sell a used one cheap, it is still a great unit.

I'm sure its a good scope but the diff probes were the only 100x ones I could see. The over voltage was only +/- 100V on the input (I think) - pretty easy to exceed with a tube amp.

[drz400]

I'm sure its a good scope but the diff probes were the only 100x ones I could see. The over voltage was only +/- 100V on the input (I think) - pretty easy to exceed with a tube amp.

You dont have to use their probes you can get 100x probes anywhere and it beats the solution of people plugging into their sound cards! 10x works for most situations

Max Input Voltage
(at BNC connector) max input voltage at probe tip depends on probe type (1x, 10x, 100x, etc.)

Probe Continuous Transient (DC + AC <10KHz)
BNC ± 50V DC ± 150V DC
1X probe: ± 50V DC ± 150V DC
10X probe: ± 500V DC ± 1,500V DC
100X probe: ± 5,000V DC ± 15,000V DC
1000X probe: ± 50,000V DC ± 150,000V DC

[nickt]

Just to be a PITA I've decided to completely change my views on this subject.

Downloaded Motörbööt's recommended FREE FOR EDUCATIONAL USE sound card scope software and have decided to check it out under controlled conditions - ie home made voltage divider probe (with diode protection) and a couple of beers.

Given my registered cheapskate status if it works *well enough* I'm happy to concede my views above totally wrong. However I still wouldn't recommend this route to someone with no electronics knowledge given the increased possibility of death due to messing with a live amp.

Will keep you posted.

[Motörbööt]

Hi,

I did NOT say, go to that page get the SW, install it and fumbel around in some high voltage gear...

Guess anyone who is thinking about buying a scope goes through this to use his PC as a scope. But like Mr. Fuchs says, there is no point.

Better get yourself a used real scope and some background how to use it and btw. an insulating transformer for safety as well!

Greetz
.

[nickt]

Hi,

I did NOT say, go to that page get the SW, install it and fumbel around in some high voltage gear...

Guess anyone who is thinking about buying a scope goes through this to use his PC as a scope. But like Mr. Fuchs says, there is no point.

Better get yourself a used real scope and some background how to use it and btw. an insulating transformer for safety as well!

Greetz
.

No you actually said "Hi <URL> Greetz" LOL

Having used scopes since 1977 hope I won't be fumbling too much - but you never know Don't own a scope personally and never have because there was always one at work - usually tektronics.

Seriously though - I'm happy to admit that there may be "another way" than my original opinion (ie buy a real scope). The software you pointed to looks nice and will probably be fine for audio work if it is not a PhD exercise jerrying up a probe that is safe to use with the sound card input.

The last part is where folks who don't know what they're doing could get into real trouble - ie become dead.

Disclaimer: do not mess with this stuff unless you are a trained technician and even then think twice.

One question: why did you post the URL if you weren't recommending it?

[drz400]

I use my DSO 2100 a lot but it is USB so my computer is pretty safe and I use it for OPAMP stuff more than Tube
For general Tube work it is hard to beat the old standard
$275 you cant go too wrong unless there is something wrong with it
http://cgi.ebay.com/TEKTRONIX-465b-100M ... dZViewItem

[jjman]

So I’m still unsure what to do. I appreciate all the comments. I couldn’t find the demo on http://www.bitscope.com/

I would only need one for audio purposes. I guess it should have a good upper range to be able to see unwanted oscillation? My major problem is that I’m not familiar with the jargon nor the key features that are good for audio/amp work. I see them for sale at the local flee market often but with no manual and verifying it’s integrity at the flea market is essentially impossible.

The “soundcard scopes” look cool but I’m wanting a little more. And I’d have to build a buffer against DC and a divider for “strong” AC (like a speaker output.) And only one channel with them right?

I understand the voltage range I’d be working with and the need (desire) for at least 2 channels. However, I am a true “Dummy” otherwise regarding scopes. Anyone have a link to “Scopes for Dummies?” I should have poked my nose into the engineering department when I worked for a DJ equipment company.

I have monitored eBay in the past, for stand-alone units, and this may be the way to go for me. Are there any key features I should look for? If probes are missing I guess I can always get them separately? Standard probe-to-scope connection for all scopes? (Can you tell I’m a dummy?) Any models/brands that are to be avoided?

I know these are subjective questions but is there a consensus on some of this?

I’d like to spend under $400. Is that reasonable using eBay for a scope for me?

[jbrew73]

can someone give me some tips on building a probe for the sound card? im not in the repair business and have never used a scope but im very familiar with tube amps and have built and repaired a few amps.

[nickt]

can someone give me some tips on building a probe for the sound card? im not in the repair business and have never used a scope but im very familiar with tube amps and have built and repaired a few amps.

I'm looking into that myself at the moment (slowly).

In real scopes the input impedance of the scope is well defined so what is used to make a x10 or x100 probes is just a precision resistor and a cap to compensate frequency response (ie stop ringing on the edges of square waves or pulses).

With sound cards - who knows what the input looks like to the probe. It would certainly vary from card to card.

I found a DIY probe via google that was from an electronics mag however haven't got much further (sorry don't have the link to hand).

My own concern with soundcard probes is grounding. If you accidentally clip the ground to +500V you really don't want to fry yourself, your card or your pc. Don't have an answer to this yet. Ideally someone might have done this already and posted info in some electronics forum.

[drz400]

For that money it is a no brainer
Get yourself a 465B

So I’m still unsure what to do. I appreciate all the comments. I couldn’t find the demo on http://www.bitscope.com/

I would only need one for audio purposes. I guess it should have a good upper range to be able to see unwanted oscillation? My major problem is that I’m not familiar with the jargon nor the key features that are good for audio/amp work. I see them for sale at the local flee market often but with no manual and verifying it’s integrity at the flea market is essentially impossible.

The “soundcard scopes” look cool but I’m wanting a little more. And I’d have to build a buffer against DC and a divider for “strong” AC (like a speaker output.) And only one channel with them right?

I understand the voltage range I’d be working with and the need (desire) for at least 2 channels. However, I am a true “Dummy” otherwise regarding scopes. Anyone have a link to “Scopes for Dummies?” I should have poked my nose into the engineering department when I worked for a DJ equipment company.

I have monitored eBay in the past, for stand-alone units, and this may be the way to go for me. Are there any key features I should look for? If probes are missing I guess I can always get them separately? Standard probe-to-scope connection for all scopes? (Can you tell I’m a dummy?) Any models/brands that are to be avoided?

I know these are subjective questions but is there a consensus on some of this?

I’d like to spend under $400. Is that reasonable using eBay for a scope for me?

[jjman]

I went for the Tektronix 2246. Looks like they go for about $250-$500 in functioning condition. I liked the idea of 4 channels. Seem like Tektronix is the predominant brand by far. No computer stuff with the 2246 but it should be a real fun toy. And it's vintage CRT technology!

I found a basic tutorial

https://www.cs.tcd.ie/courses/baict/bac ... scope.html

It definitely helped me learn some basics, especially about the whole "trigger" thing.

Thanx for all the comments!

[Sonny ReVerb]

Tektronix has a good tutorial as well:

http://www.tek.com/Measurement/App_Note ... 8605_2.pdf