Go Back   Home > Forums > >

Equipment & Tools From test equipment to hand tools

Oscilloscope versus usb card?
Oscilloscope versus usb card?
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools
Old 16th September 2020, 02:19 PM   #21
nigelwright7557 is offline nigelwright7557  United Kingdom
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Got a crash course in probes when I did my first USB scope design !
Always use 10x or 100x as x1 will produce a fast roll off due to 10pf scope input capacitance.
In x10 and x100 mode the 10pf is offset by caps in the scope probe and so you get better bandwidth.
__________________
2020 versions of PCBCAD51 and PCBCAD720 out now >>> https://www.murtonpikesystems.co.uk
  Reply With Quote
Old 16th September 2020, 02:52 PM   #22
Vovk Z is offline Vovk Z  Ukraine
diyAudio Member
 
Join Date: Oct 2011
Location: Kyiv
Quote:
Originally Posted by r_jik45 View Post
Thanks for the comments so far.
Looks like usb cards are not much recommended.
They can be good (or better) at some specific things (as it was described here), but in general it is good to have an individual oscilloscope.

Last edited by Vovk Z; 16th September 2020 at 02:54 PM.
  Reply With Quote
Old 16th September 2020, 02:56 PM   #23
Vovk Z is offline Vovk Z  Ukraine
diyAudio Member
 
Join Date: Oct 2011
Location: Kyiv
Quote:
Originally Posted by nigelwright7557 View Post
Always use 10x or 100x as x1 will produce a fast roll off due to 10pf scope input capacitance.
10-15 pF of a scope input and 100-200 pF of a cable (at x1).
  Reply With Quote
Old 16th September 2020, 03:47 PM   #24
jan.didden is online now jan.didden  Europe
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Westende Resort, BE coast
Quote:
Originally Posted by JRE View Post
Triangle and square waves contain harmonics of the base frequency. To see them accurately, you have to consider the frequency content of the harmonics rather than just the base frequency.
Of course. If we talk about bandwidth it is reasonable to assume people mean the highest frequency they want to look at.

Jan
  Reply With Quote
Old 17th September 2020, 06:29 AM   #25
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Oscilloscope versus usb card?
I have examples of both USB scopes (200 MHz) dedicated digital scopes (Siglent and Tek) and analog scopes. The first figure of merit is the analog bandwidth. If the analog circuit rolls off more samples won't help. Second, you should have at least 5X sample rate over the bandwidth limit or you will get into a lot of ugly aliasing and other misleading stuff. Digital scopes can be really misleading if you don't understand how they work. Buffer size is an issue. Too small and you will miss stuff. Too big and it takes a long time to load and show the waveform. What you see is never instantaneous like an analog scope.

All digital scopes are very much a product of the software and some of the cheap ones have pretty limited software. I like the Picoscope software and its continuous improvement (for no cost). However their USB scopes are more expensive.

However a cheap tool that is not useful is actually far more expensive than an expensive tool you use. (I have a collection of those useless cheap tools. . .)

Do not get distracted by features you will never use (serial decoding, mediocre FFT etc.) and don't pay for them if you can avoid it.

For occasional use a USB scope can be quite adequate and stores in a small place. A digital scope will be larger but self contained and analog scopes will be large to really large and power hungry. My old TEk 547 used 500W. The 7854 uses 150W. The Siglent maybe 20W and the Picoscope runs on USB power (2.5W). (However the sampling plugins on the 7854 get me to 20 GHz which would be crazy expensive any other way so its still using a lot of floor space.)
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 17th September 2020, 01:23 PM   #26
Vovk Z is offline Vovk Z  Ukraine
diyAudio Member
 
Join Date: Oct 2011
Location: Kyiv
Well said. Somebody have to glue this info to the every new topic about how to choose a scope.
  Reply With Quote
Old 17th September 2020, 01:36 PM   #27
tommost is offline tommost
diyAudio Member
 
Join Date: Sep 2013
Quote:
Originally Posted by jackinnj View Post
bandwidth is of little relevance if you don't have high quality probes, and while you're at it, read up on probing technique! Keysight and Tektronix have white papers on probing technique.
Well said Jack. A large number of the customer complaints on regulator noise I used to see were really due to improper probing.

PS I noticed your location, first I didn't think that village was in NJ, second are you the only DIYer in the village?
  Reply With Quote
Old 17th September 2020, 02:03 PM   #28
jackinnj is offline jackinnj  United States
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Oscilloscope versus usb card?
Quote:
PS I noticed your location, first I didn't think that village was in NJ, second are you the only DIYer in the village?
That was a particularly funny episode Daffyd.
  Reply to this post

Reply


Oscilloscope versus usb card?Hide this!Advertise here!
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Sound Card Versus Amplifier Menel Headphone Systems 7 21st August 2010 07:50 AM
PCI Oscilloscope card Bushulo Solid State 1 30th August 2007 06:54 AM
Oscilloscope probes for sound card stef1777 Parts 4 9th May 2007 10:55 PM


New To Site? Need Help?

All times are GMT. The time now is 04:05 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki