Just for fun: The Regulator-Chip amplifier - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

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
Thread Tools Search this Thread
Old 16th October 2010, 09:33 AM   #1
Elvee is offline Elvee  Belgium
diyAudio Member
Elvee's Avatar
Join Date: Sep 2006
Default Just for fun: The Regulator-Chip amplifier


Here is a little exercise in style: to design a complete class B amplifier using almost exclusively voltage regulator chips (only one discrete transistor is used at the input).

The results are quite surprising: the simulation shows it works nicely, and even more surprising, the reality agrees very well with the sim.
At 1KHz, the distortion is quite low (the actual measured figure is ~0.05%, but it isn't bad anyway).

The quiescent current is very stable and predictable, and there is no risk of thermal runaway, thanks to the tight regulation.
Moreover, the circuit is inherently immune to short-circuits and over heating, thanks to the internal protections of the chips.

There is one snag however: the chips are slow, and if a certain slew rate is exceeded, the waveform breaks down: this is visible on the 7KHz oscilloscope screenshot (the same happens in sim, but at a higher frequency).
The prototype used a LM336 instead of the LT1009.

Have fun!
Attached Images
File Type: gif ChipAmp.gif (33.8 KB, 832 views)
File Type: jpg ChipFront.JPG (259.0 KB, 801 views)
File Type: jpg ChipTop.JPG (218.1 KB, 725 views)
File Type: jpg Chip1KHz.JPG (313.7 KB, 680 views)
File Type: jpg Chip7KHz.JPG (332.3 KB, 643 views)
  Reply With Quote
Old 16th October 2010, 09:45 AM   #2
Luke is offline Luke  New Zealand
diyAudio Member
Join Date: Sep 2001
Send a message via AIM to Luke
nice, how does it sound:-)
If you give a man a fish he will eat for a day. But if you teach a man to fish he will buy an ugly hat. And if you talk about fish to a starving man then you are a consultant. Dilbert
  Reply With Quote
Old 18th October 2010, 11:23 PM   #3
diyAudio Member
Speedskater's Avatar
Join Date: Sep 2002
Location: Lakewood, Ohio
Always wondered how well they would work! We talked about it at lunch back in the mid-1980's, but that's as far as it got.
  Reply With Quote
Old 20th October 2010, 02:11 AM   #4
CLS is offline CLS  Taiwan
diyAudio Member
Join Date: Jun 2005
Location: Taiwan
How interesting

I'm wondering if it's possible to design a "quasi-complimentary" version? It could be, right? I'm no expert, but it's commonly seen that the positive Vregs are slightly better than negative ones.

So, how about one with 2 LM338, maybe approaching 100W per channel At least at its peak.
  Reply With Quote
Old 21st October 2010, 02:19 PM   #5
Elvee is offline Elvee  Belgium
diyAudio Member
Elvee's Avatar
Join Date: Sep 2006
Originally Posted by CLS View Post
How interesting

I'm wondering if it's possible to design a "quasi-complimentary" version? It could be, right? I'm no expert, but it's commonly seen that the positive Vregs are slightly better than negative ones.
With a quasi-complementary, you'd still need a low power negative regulator.
But these devices already have a huge transconductance compared to any discrete, and cascading them looks a like a sure method to get uncontrollable oscillations.

I have considered alternatives: the circlotron is one of them, but there is a difficulty: compared to a MOS or a BJT, voltage regulators are depletion devices: they need a negative bias on their control electrode (=~base) wrt. the reference electrode, the output (=~emitter).
This means that for class B operation, you'd need a small negative auxiliary supply of ~1V.
Not very practical.
Class A would be possible, a bit like a tube: the cathode resistor would provide the negative bias.
Note that by operating at a higher quiescent current, it is possible to remove the artifacts seen on the 7KHz sinewave.

nice, how does it sound:-)
Normally, since I have tin ears, I don't perform this kind of tests. I don't want to make a fool of myself, and I prefer to let others do it.
I did feed some music however, and it sounded normal: there was no gross deficiency, and without knowing I certainly wouldn't be able to distinguish between this amplifier and a "normal" one.
This probably means the content of the program remained below the critical slew rate, because if it had been exceeded, even I would have detected it.
  Reply With Quote


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
Placing regulator chip close to amplifier terranigma Power Supplies 4 8th June 2010 08:47 AM
Help needed to identify a boost regulator chip. ashok Power Supplies 11 15th September 2009 03:53 AM
Fun with a Philips TDA1517P chip? AdamThorne Chip Amps 6 2nd February 2008 09:48 PM
What Amplifier Chip to use? nicku1302 Chip Amps 8 15th November 2007 03:10 AM
Chip Amplifier MikeMe Chip Amps 0 7th March 2007 11:15 PM

New To Site? Need Help?

All times are GMT. The time now is 06:46 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2