jonnyGURU Forums
Home Site Search Reviews Articles Contest Links PSU FAQs  


Go Back   jonnyGURU Forums > General Electronics > Electronic Theory and Principle

Electronic Theory and Principle Discussion of electrical theory, law, etc.

Reply
 
Thread Tools Display Modes
  #1  
Old 12-30-2010
TheLaw's Avatar
TheLaw TheLaw is offline
Abacus Overclocker
 
Join Date: Dec 2010
Posts: 128
Thanks: 0
Thanked 0 Times in 0 Posts
Default What Bandwidth O-Scope for SMPS/Linear power supplies?

Hi,

I'm getting into electronics quite a bit. My main attraction is power supplies at the moment. I've been putting together a collection of switching and linear supplies ranging in all sorts of topologies.

I'd like to buy an O-Scope off ebay or maybe one of these new DSO o-scopes on SeeedStudio.

However, I don't know what frequency range and/or how much bandwidth the scopes need to measure. (Weird wording, sorry). Is 30Mhz sufficient? Or do I need more? Like 100Mhz? More?


Thanks.ss
__________________
Awesomesauce
Reply With Quote
  #2  
Old 12-30-2010
Spectre Spectre is offline
Pinball Wizard
 
Join Date: Oct 2006
Location: Moderator
Posts: 3,959
Thanks: 10
Thanked 55 Times in 31 Posts
Default

20MHz
Reply With Quote
  #3  
Old 12-30-2010
TheLaw's Avatar
TheLaw TheLaw is offline
Abacus Overclocker
 
Join Date: Dec 2010
Posts: 128
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Thanks!
__________________
Awesomesauce
Reply With Quote
  #4  
Old 01-04-2011
Travis's Avatar
Travis Travis is offline
PSU backseat driver
 
Join Date: May 2008
Location: Beijing, China
Posts: 2,320
Thanks: 3
Thanked 27 Times in 20 Posts
Default

If you're going to measure the rising/falling edge of SMPS or the switching transients with some high frequency details, 100MHz bw should come in handy since higher bw means faster response.
__________________
Engrish is my second language.
Protect your kid from e-Porno with Green Damn.
Reply With Quote
  #5  
Old 08-03-2012
dish_moose dish_moose is offline
micro ATX User
 
Join Date: Apr 2012
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Default

With SMPS having faster switching frequencies(more efficient smaller inductors) the rise time and dead time have to be very fast. A slow scope cannot display the rise and fall times correctly. Linear supplies - a 20 MHz scope will work fine. SMPS need fast scopes with the proper probes otherwise the noise induced in the probe will be what you measure.
-Bruce
Reply With Quote
  #6  
Old 09-04-2012
Digerati's Avatar
Digerati Digerati is online now
Built, Broke, Fixed, Learned.
 
Join Date: Jan 2011
Location: Nebraska, USA
Posts: 209
Thanks: 0
Thanked 11 Times in 10 Posts
Default

I have always been taught to go by the rule of thumb and try (if budget allows) to purchase a scope with a bandwidth five times higher than the maximum frequency to be measured. This is to ensure you capture up through the 5th harmonic so you can get a sharply defined waveform (and to spot anomalies).

I think, unless you will be limiting your testing to slow switching devices like power supplies, it is a mistake to buy a scope that will not really help you with your other electronics - like testing high-speed USB3.0 ports.

You should look at the fastest scope your budget will allow - then double it.

If me, I would get no less than 200MHz, but frankly, I would be looking at 2GHz to hopefully ensure the scope's usefulness further into the future.

If budget is really tight, I would still wait until it can be increased to afford at least the PicoScope 3000 Series, or something similar.
__________________
Bill (AFE7Ret)
Freedom is NOT Free!
MS MVP Windows Expert-IT Pro 2007 - 2015

Heat is the bane of all electronics!

───────────────────────────
Reply With Quote
Reply

Thread Tools
Display Modes

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


All times are GMT -4. The time now is 09:43 AM.


Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.