Essential tools switching amps and smps - diyAudio
Go Back   Home > Forums > Design & Build > Equipment & Tools

Equipment & Tools From test equipment to hand tools

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 Search this Thread
Old 13th October 2013, 12:40 PM   #1
FQR is offline FQR  Germany
diyAudio Member
 
Join Date: Nov 2012
Location: Bad Birnbach, Bavaria
Default Essential tools switching amps and smps

Hello!

What is the minimal equipment for building a class-d low-bandwidth bass amplifier (maximal frequency 150 Hz)?

For example, i got to formulate one of the points more exactly: Often there are unwanted oscillations (i think, most of them in the MHz-range, and independent of the planned low switching frequency).

For analysis one needs a scope which can deal with that, so: What is the recommendable minimum?


FQR

Last edited by FQR; 14th October 2013 at 04:37 PM. Reason: Question seemed to be too long. No answer.
  Reply With Quote
Old 13th October 2013, 11:17 PM   #2
FQR is offline FQR  Germany
diyAudio Member
 
Join Date: Nov 2012
Location: Bad Birnbach, Bavaria
So, nobody can (or wants to) give me the information, which minimum bandwidth such a scope should have, to analyse such ringing, overshoot, jitter etc. faults the right way? (So that every possible fault would be visible and i would even be able to allocate the root of it)???
  Reply With Quote
Old 15th October 2013, 06:43 PM   #3
diyAudio Member
 
PedroDaGr8's Avatar
 
Join Date: Dec 2009
Location: San Diego, CA
It's not that they don't want to but they may not know and/or they may view the fact that you have to ask implies you may not have the knowledge.

That being said there are a few things you will need:

The first is a scope as you mentioned. Most of the time 20-30Mhz analog should be enough to see what you need to see. I'd double that if digital. Either way, its not too difficult to get.

Now comes the difficult part. Because of the nature of the switching and the voltages involved, from my experience you NEED a differential probe. These can be VERY pricey. You can sometimes get by working on a switching device without one but when things go wrong they become essential.

The third is often times a quality LCR device (one with a kelvin connection and capable of more than one or two frequencies).

Last edited by PedroDaGr8; 15th October 2013 at 06:45 PM.
  Reply With Quote
Old 15th October 2013, 07:21 PM   #4
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
And if you are going to do any work on an SMPS, PLEASE use isolation transformers.
  Reply With Quote
Old 15th October 2013, 07:53 PM   #5
diyAudio Member
 
PedroDaGr8's Avatar
 
Join Date: Dec 2009
Location: San Diego, CA
Quote:
Originally Posted by Enzo View Post
And if you are going to do any work on an SMPS, PLEASE use isolation transformers.
Thanks, forgot to add that in there.
  Reply With Quote
Old 15th October 2013, 10:17 PM   #6
diyAudio Member
 
Join Date: Nov 2010
Location: N.E. PA
Very handy is a current probe. Look for a used TEK, like a 6042. You should be able to find one for @ $250-300 It is a 50 MHz unit. Very handy to see peak current, look for saturation in transformers and inductors, etc. I've had one for years and never regret buying it.

Of course a scope is a necessity. 50 MHz is a nice unit. Again used TEKs are great buys and generally rock solid investments.

paul
  Reply With Quote
Old 16th October 2013, 02:34 AM   #7
FQR is offline FQR  Germany
diyAudio Member
 
Join Date: Nov 2012
Location: Bad Birnbach, Bavaria
Thanks very much, guys! :-)

I donīt know nothing, but i have not enough net access to search all that i gotta know. Ok, so iīll need a scope with the mentioned bandwidth, and those (or other - i want to be able to deal with more than 10 amperes) fitting probes. Yes, i also favor tektronix - itīs a terrific quality brand!

Until now my LCR-meter is not so good - itīs only a victor vc88, has only only one measuring frequency, and is a little unaccurate.

Only good thing. i already have, is a big amount of things related to 50Hz AC and some to DC, cause with line level things iīve been working nearly every day of the least 20 years.

And fortunately this means really many meters, circuit breakers, fuses, relays, switches, heavy electrolytic caps, diodes, chokes and transformers, in all imaginable versions and power classes. Thats better than one isolation tranny of one size, itīs even more flexible than any laboratory linear supply. Because i can make thousands of combinations for test powering with the right voltage and limited as good as fused current.

And i got nearly 40 pcs. of IRFPC50A, and over 30 pcs. IRFP450, of which i want to build an adjustable electronic load for testing. Until now i donīt know exactly how i should build it the best way. But that would probably be a new topic here... ;-)

Again, many thanks to all!

Last edited by FQR; 16th October 2013 at 02:35 AM. Reason: ...forgot something.
  Reply With Quote
Old 17th October 2013, 12:37 AM   #8
diyAudio Member
 
PedroDaGr8's Avatar
 
Join Date: Dec 2009
Location: San Diego, CA
Quote:
Originally Posted by FQR View Post
Thanks very much, guys! :-)

I donīt know nothing, but i have not enough net access to search all that i gotta know. Ok, so iīll need a scope with the mentioned bandwidth, and those (or other - i want to be able to deal with more than 10 amperes) fitting probes. Yes, i also favor tektronix - itīs a terrific quality brand!

Until now my LCR-meter is not so good - itīs only a victor vc88, has only only one measuring frequency, and is a little unaccurate.

Only good thing. i already have, is a big amount of things related to 50Hz AC and some to DC, cause with line level things iīve been working nearly every day of the least 20 years.

And fortunately this means really many meters, circuit breakers, fuses, relays, switches, heavy electrolytic caps, diodes, chokes and transformers, in all imaginable versions and power classes. Thats better than one isolation tranny of one size, itīs even more flexible than any laboratory linear supply. Because i can make thousands of combinations for test powering with the right voltage and limited as good as fused current.

And i got nearly 40 pcs. of IRFPC50A, and over 30 pcs. IRFP450, of which i want to build an adjustable electronic load for testing. Until now i donīt know exactly how i should build it the best way. But that would probably be a new topic here... ;-)

Again, many thanks to all!
An adjustable electronic load is NOT easy at all. You have to fight oscillations, non-matching resistances, the effects of non-balanced loading on the transistors etc. it is dramatically harder than just a power supply. In its most basic form (one FET/BJT) then it can be easier but anything beyond that can become VERY difficult VERY quick.
  Reply With Quote
Old 23rd October 2013, 04:47 AM   #9
FQR is offline FQR  Germany
diyAudio Member
 
Join Date: Nov 2012
Location: Bad Birnbach, Bavaria
Hello Pedro,

youīre surely right, there are many different kinds of electronic loads, and they can have many functions. Some of them are even programmable, you can determine a series of different conditions, changing in fixed ways, before starting. Building something like that is nearly impossible for me. But even building much simpler ones could bring trouble.

By thinking about my concrete demands i found a possible solution for fundamental testing of smpsīs with symmetrical output: Eventually i could build a quasi-complementary amp, able to stand this outputs easily (what means possible high voltage and current). And feed it from a frequency-generator. Between the generator and the amp i could build a network of switches, potentiometers and resistors, to control the input and so likewise the output, what controls the power demand, too.

That would not be too difficult. I know, thatīs not the same as a real electronic load, with functions like fixed current, fixed voltage, ... etc., but some testing would be possible with it. For the final loudspeaker load i could use loudspeakers and/or a network of resistors (and maybe chokes and capacitors), to simulate some fundamental conditions.

What do you all think?

Greets,


FQR

Last edited by FQR; 23rd October 2013 at 04:48 AM. Reason: made an essential fault
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
smps switching frequency and noise soundnovice Power Supplies 4 30th May 2012 05:36 AM
Stable switching speeds for IGBTs in SMPS design thadman Power Supplies 4 11th April 2010 10:39 PM
Punch tools for making metal top plates on amps jmillerdoc Tubes / Valves 25 11th November 2009 04:04 PM
Question: SMPS switching frequency with 41Hz Amp4 DVBjunky Class D 34 18th March 2008 08:47 AM
Zero Voltage Switching for Class D amps hdoggz Class D 1 6th April 2005 08:30 PM


New To Site? Need Help?

All times are GMT. The time now is 10:59 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2