ISO "Simplest" possible amplifier - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 21st February 2009, 11:55 PM   #11
diyAudio Member
 
Join Date: Aug 2003
Location: Calgary on the Bow
Default check these...

http://www.diyaudio.com/forums/show...&threadid=42259

http://www.dddac.de/op06.htm
__________________
moray james
  Reply With Quote
Old 22nd February 2009, 10:17 PM   #12
amz-fx is offline amz-fx  United States
diyAudio Member
 
Join Date: Sep 2004
Location: s. Louisiana
Dano,

I built a small amp similar to this one and it worked just fine on 9v to 12v, but not terribly loud.

I would suggest that R1 be changed 100k or even 1M. Also the C1 input capacitor needs to be turned around so the plus side is to the mosfet.

When used with 9v, mine did not get hot enough that a heat sink was even necessary, though I did not drive it hard for long periods.

regards, Jack

http://www.muzique.com/
  Reply With Quote
Old 22nd February 2009, 10:23 PM   #13
Fuling is offline Fuling  Sweden
diyAudio Member
 
Join Date: Aug 2001
Location: Sweden (Mora)
Ive built a couple of amps quite similar to the one in post 3 and with the right speakers this topology has some nice features.
(fullrange drivers sometimes sounds better mated with high Zout amps).

Driving the Mosfets input capacitance requires and active preamp though.
  Reply With Quote
Old 23rd February 2009, 01:29 PM   #14
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
"Any ideas on what I've done wrong?"

You don't have a schematic that's useable.

130mA?

If R2 was an active current source, then 130mA of bias would be 0.092 mA into an 8 ohm speaker. (I^2)R=0.067W

67milliwatts.

Throw away this schematic.

Read this:

http://www.passdiy.com/pdf/zenamp.pdf

Circuit board here:

http://www.audioxpress.com/bksprods/...ts/pcbp-11.htm
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 23rd February 2009, 02:21 PM   #15
dano12 is offline dano12  United States
diyAudio Member
 
Join Date: Mar 2006
Location: NoVa
Thanks guys for all the advice.

Turned out that I hadn't properly grounded the source of the FET (doh!). After doing that it fires up fine.

I'm running it at 18 volts, the FET barely gets warm but the 50 ohm resistor get's very hot. I'll take the recommendation and remount it on a heat sink.

Jack, thanks for the ideas. I actually used your excellent MOSFET boost as a preamp.

I'll reverse the cap and do some more tinkering tonight.
  Reply With Quote
Old 23rd February 2009, 02:38 PM   #16
diyAudio Member
 
Join Date: Jan 2002
Location: Tyrone Ga. U.S.A.
If you are running it at 18v you could replace that 50 ohm
resistor with a 12v turn signal light bulb.

What are you using as a input source? If your input source
is a something like a cd or sound card you might get better
results with these componints using them in a source follower.
  Reply With Quote
Old 23rd February 2009, 10:28 PM   #17
dano12 is offline dano12  United States
diyAudio Member
 
Join Date: Mar 2006
Location: NoVa
As far as I'm concerned, mission accomplished with this one. I fashioned a hillbilly heatsink for the power resistor, stuck a single transistor pre-amp in front of it, stuck it in a computer CDROM cage and called it a day.

Click the image to open in full size.

It makes a nice little guitar amp, drives an 8 ohm cab very well.

I think now I'll move on to some of the better suggestions posted here.

Thanks again for the pointers!
  Reply With Quote
Old 23rd February 2009, 11:18 PM   #18
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
If you replace the resistor with an LM317 regulator it will double the efficiency of the amplifier, and double the output power, and the regulator will probably cost less than the resistor.
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 23rd February 2009, 11:19 PM   #19
mosfets is offline mosfets  Canada
diyAudio Member
 
Join Date: May 2008
Quote:
Originally posted by dano12
... I fashioned a hillbilly heatsink for the power resistor, stuck a single transistor pre-amp in front of it, stuck it in a computer CDROM cage and called it a day

That is the coolest piece of crXp I've ever seen on DIY! I want one just like it STAT.
  Reply With Quote
Old 24th February 2009, 12:35 PM   #20
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
http://sound.westhost.com/project83.htm
  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
What makes an amplifier "bright", "warm", or "neutral"? JohnS Solid State 51 13th December 2009 06:42 PM
He helps with amplifier " Lineal Power" Model 652IQ diegodgo Car Audio 1 28th October 2006 08:05 PM
LM3886 GC - "Simplest Ever Amplifier Bridging" jweber Chip Amps 20 18th June 2006 02:55 AM
Newbie wants to build a "GainClone-Like" 5.1 Channel Battery Powered Amplifier captain Chip Amps 7 15th October 2004 12:35 PM


New To Site? Need Help?

All times are GMT. The time now is 12:08 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2