Suggestions on a cheap Digital oscilloscope

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trend

Joined: 14 Dec 2004
Posts: 86
Helped: 5

07 Jan 2005 10:49 digital oscilloscope cheap

Hello, I have been semi following the Digital oscilloscope Project, and that has got me to the point of me wanting one.. but just not having enough time to build one.

What do you'll suggest for a Digital oscilloscope? I would like something inexpensive to get me started... preferably ~$100.

I looked into the gameboy Digital oscilloscope, but I am not sure how good this is (is it worth the money?)
I definitly like the portability of it.. that is huge, but if it doesn't work .. :/

If the only decent one is computer controlled, I might just have to go with that for the time being...

What do you'll think of all the "old" ones on ebay? do models really very that much (for the hobbiest?)

thanks guys!
Lee

XNOX_Rambo

Joined: 13 Jul 2002
Posts: 437
Helped: 87
Location: Far out, man!

07 Jan 2005 12:06 cheap digital oscilloscope

Hi,

I suggest you go for something like this:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=45014&item=3865679322&rd=1

/Rambo

trend

Joined: 14 Dec 2004
Posts: 86
Helped: 5

08 Jan 2005 7:35 Re: Suggestions on a cheap Digital oscilloscope

Yeah, I would like a fluke... but they are way out of my ~$100 price range :/

thanks though!

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echo47

Joined: 07 Apr 2002
Posts: 4206
Helped: 566

08 Jan 2005 10:41 Suggestions on a cheap Digital oscilloscope

$100 digital scope on eBay - hmmm. You won't find much at that price, except broken fixer-upper units.

How about a plug-in card for your PC? I don't know if this product is any good, but it's in your price range:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3865064886

trend

Joined: 14 Dec 2004
Posts: 86
Helped: 5

09 Jan 2005 5:41 Re: Suggestions on a cheap Digital oscilloscope

ISA.. yuck :/

thanks though

echo47

Joined: 07 Apr 2002
Posts: 4206
Helped: 566

09 Jan 2005 6:47 Suggestions on a cheap Digital oscilloscope

Oops, I missed that. Got an old 486 computer sitting around? Build yourself a museum artifact!

If you don't have any scope yet, buy a used analog scope first.

trend

Joined: 14 Dec 2004
Posts: 86
Helped: 5

09 Jan 2005 7:33 Re: Suggestions on a cheap Digital oscilloscope

why an analog scope ? what is the diff :/

echo47

Joined: 07 Apr 2002
Posts: 4206
Helped: 566

09 Jan 2005 8:09 Suggestions on a cheap Digital oscilloscope

Several years ago, a Tektronix sales engineer came into my office hoping to sell me their latest $30,000 TDS784 digital scope. I listened to his sales pitch, and then pulled from my pocket a small device powered by a 9V battery and said, "show me the signal on this output pin." For about fifteen minutes he pushed buttons and turned knobs, struggled with aliasing and uncertain trigger level, but he couldn't get a sensible display. I powered-up my trusty old Tek 465B analog scope, and in a few seconds we saw the sinewave+pulse waveform clear as day. The 9V powered device was an old oscilloscope demo board made by Tektronix!

If you know exactly what you want to measure, digital scopes are great. But if you are just poking around a circuit ... well ... I did not buy that fancy new $30,000 digital scope. Even today, I still use analog scopes most of the time.

You can get a halfway decent used analog scope for $100.

trend

Joined: 14 Dec 2004
Posts: 86
Helped: 5

09 Jan 2005 9:46 Re: Suggestions on a cheap Digital oscilloscope

thanks!

After a quick google search.. I still cannot tell the diff between an analog oscilloscope and digital oscilloscope.

Can you explain please.

Thanks for the help, I believe I am going to take your suggestion and go with an analog one (once I know for sure I will be able to understand how to use it Smile

)

thanks! Lee

echo47

Joined: 07 Apr 2002
Posts: 4206
Helped: 566

09 Jan 2005 11:02 Suggestions on a cheap Digital oscilloscope

Well, I'm an old fart that likes doing things the old way, so please read some more before deciding!

Here's a good document. Maybe it will help you decide. (By the way, Tek doesn't sell analog scopes anymore.)

"XYZs of Oscilloscopes":
http://www.tektronix.com/Measurement/App_Notes/XYZs/

In particular, "Types of Oscilloscopes":
http://www.tek.com/Measurement/App_Notes/XYZs/types_osc.pdf

A $100 eBay analog scope will probably be 20+ years old and may need some (hopefully minor) repair.

checkmate

Joined: 25 Feb 2004
Posts: 489
Helped: 35
Location: Toilet Seat

09 Jan 2005 11:16 Re: Suggestions on a cheap Digital oscilloscope

An analog scope is similar to a TV. It just translates input signals into screen output.
A digital scope on the other hand is like a capture card. It does an ADC on an input signal, stores them in memory, and displays them on a screen. Owing to the high sampling rates used, it usually involves a substantial amount of memory.

As digital scopes have memory, you can essentially "freeze" the display. Hence, it allows the capturing of non-periodic signals. For analog scopes, a non-periodic signal would just flash by.

Digital scopes also have the added capability to output to a PC.

trend

Joined: 14 Dec 2004
Posts: 86
Helped: 5

09 Jan 2005 23:13 Re: Suggestions on a cheap Digital oscilloscope

hmm..

The XYZs of Digital O's does not work.. but this does:
http://www.optics.arizona.edu/Palmer/OPTI380B/PDFdocs/TekXYZ_Scopes.pdf

trend

Joined: 14 Dec 2004
Posts: 86
Helped: 5

11 Jan 2005 3:32 Re: Suggestions on a cheap Digital oscilloscope

what you'll think of this:

http://www.parallax.com/detail.asp?product_id=28119
?

thanks!

echo47

Joined: 07 Apr 2002
Posts: 4206
Helped: 566

11 Jan 2005 10:04 Suggestions on a cheap Digital oscilloscope

I've never used the Parallax scope, but it looks like a toy. Only 500 kHz sample rate and 200 kHz bandwidth. It would be useful for some specific applications, but almost everyone needs more bandwidth than that.

trend

Joined: 14 Dec 2004
Posts: 86
Helped: 5

11 Jan 2005 23:36 Re: Suggestions on a cheap Digital oscilloscope

Yeah, that is sorta what they said.. It can only measure up to 12v. The main idea of having this scope is the portability (hook it up toa laptop) and be able to debug iC/uC's like the bs2 (and maybe other uCs)

Anyone have a better product like this for around the same money?