OT: scope recommendations?

Seems like an awful question. But, I would say go Ebay with something cheap and is working properly.

I use to suggest Hameg analog/digital scopes, but that was before I tried to use one !!!

greg

PC-based USB-interfaced 'scopes tend not to have stellar sample rates. There's usually a note in the fine print that the advertised sample rate is "equivalent time sampling" which is okay for repetitive waveforms but not so much for single event captures -- and single events are one of the nice things you get with digital scopes.

GW Instek and Rigol each have reasonably-priced 100 MHz, 1 Gsps dual channel models that could be a starting point for comparison

--
Rich Webb     Norfolk, VA

For basics, I would advice him to run a soundcard-as-scope program on his PC. Freeware widely available and suitable for basic stuff. Let him note the limitations he observes and that will give him his 'shopping list' when buying a real scope.

See ? :-)

--
Kind regards,
Gerard Bok

I've never used a pc scope - is it easy for a novice (or absent minded old-hand) putting the probe where he shouldn't and blowing up the whole pc , not just the input FETs

What's cheaper, blowing a scope's input FETs or blowing a PC's soundcard ? And what's easier to repair / replace ? Imho scopes are both less foolproof and less forgiving than PCs.

You may not agree, but I stand by my advice. I can only add, that --indeed-- some folks shouldn't be allowed to be to close to anything that has wires attached. For those folks: learn electronics by books only, don't try hands on ;-)

--
Kind regards,
Gerard Bok

c ,

I have had concerns about that myself, especially since most PCs that I have seen in at least the last 10 years have the 'sound card' imbedded into the motherboard rather than being a plug in. Since the voltage range of the sound input is likely only +/- 12V [or less] I would also think that some form of variable attenuator is needed 'outboard' if the intention is to measure any signals [voltages] greater than common logic levels. On the other hand, I have worked with 'scopes in R&D for the last 50 years and can recall only one case where a 'scope input was damaged, and that due to gross stupidity.

Neil S.

Yeah, I think loaning him mine is best for now, and keeping an eye on Craigslist in the meantime. Gotta be more than a few scopes gathering dust in garages and attics.

As far as what he's doing, one usenet dilemma is balancing too little info against too much info. But since you asked ... My friend transfers film for a living (mostly old 8mm home movies onto DVD) and is designing / building a "flash scanner" which rather than stopping the film at every frame, runs the film continuously and relies on a very bright, very short duration strobe to freeze and capture the image directly onto a video camera.

The project involves several disciplines and a modest amount of systems integration to tie it all together. I've been working with him a bit on the mechanical design aspect and doing some machining for him. He's trying to learn enough electronics (and I don't know enough to be of all that much help to him on that end) to figure out how to sync the film, the strobe, and the camera together.

Not clear how the strobe improves on the flash of light you get from the shutter in the projector??? You're trying to sync the film, the flash and the scanner. I'd just use a standard mechanical shutter and a photocell, to sense the already-synchronized light flash to control the projector speed...all PLL'd to the scanner acquisition rate. That'd allow simple phase control.

If you're not working on the digitizer, most of your problems will be with synchronization. You're gonna want a DC coupled scope with STABLE DC coupled triggering to work at low frame rates. That takes soundcard acquisition off the table.

snipped-for-privacy@zonnet.nl (Gerard Bok) wrote in news: snipped-for-privacy@News.Individual.NET:

a scope's input-Z and circuit loading is known and minimal (1 MegR,~20-40pf),where a soundcard will have a much lower Z and more circuit loading. Newbies will not be aware of such loading effects.

I'd go for a TEK low end LCD scope,for a new model. TDS2200?

for a beginner on a tight budget,maybe a T922/T932/T935,those can be had very inexpensively,are simple to operate.

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Jim Yanik
jyanik
at
localnet
dot com

How many scopes have you blown up? I've used them for 45 years and never blown up the input on one.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

borrow

about

but

it.

Am I missing something here - why real time speed of 24 fps or whatever for

8mm. Slow it right down and software to convert to real time colour correction /scratch "removal" etc , audio synced in off realtime or speeded up separately .

From what I read here, I would suggest your friend to put the frame scan setup aside for a while and investigate the use of a linescanner. That will allow him to ditch the jumpy filmtransport altogether and scan the film right upto the maximum (continuous) speed his electronics can handle and convert. (That's the very same way some old microfilmscanners operated :-)

--
Kind regards,
Gerard Bok

I've never blown a scope :-) But N_Cook was worried someone would :-)

--
Kind regards,
Gerard Bok

snipped-for-privacy@zonnet.nl (Gerard Bok) wrote in news: snipped-for-privacy@News.Individual.NET:

I've replaced a lot of blown input FET pairs on TEK scopes. also several melted input BNCs.

and replaced countless power cords that had their ground pin cut off.

--
Jim Yanik
jyanik
at
localnet
dot com

,

Him, I can understand.

I've repaired a lot of scopes, put they were mostly bad transformers or power supplies. I saw a lot of bad resistors in the Focus/Intensity circuit on cheap scopes too.

--
You can't fix stupid. You can't even put a band-aid on it, because it's
Teflon coated.

Weren't those the ones made as a joint effort with Sony? Sort of Tek's experiment with bottom feeding?

Not good enough for the lab and too expensive for the shop.

Jeff

e t

I've got a 50MHz Rigol that I like. DS1052. $400.00

We bought OWON for a bit less, But I would stay away from that one.

George H.

from the

=20

Basically it captures one line at a time. Step and repeat for umpty hundred (or few thousand) lines to get a frame. The same counters that align the framing are used here as well. Continuous lamp focused as a line (or special and expensive "line lamp").