Mystery MOSFET mono amplifiers with 2SK135 and 2SJ50 - a little help? - 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 28th April 2012, 10:15 AM   #11
Banned
 
Join Date: Jan 2005
It'd work but i think it would be better to run both off the same transformer winding, or have two totally separate windings isolated from each other.

Last edited by Tekko; 28th April 2012 at 10:32 AM.
  Reply With Quote
Old 28th April 2012, 10:58 AM   #12
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
Default Maplin 150W MOS-FET Amplifier Module

This was a good example of the use of the Hitachi MOS-FETs that gave good and reliable results at low cost.

During 2005 I was actually in negotiations with Maplin to produce a commercial version of this same circuit.

Dollar for Dollar it is PRETTY GOOD.
Attached Images
File Type: jpg 001.jpg (768.1 KB, 196 views)
File Type: jpg 002.jpg (888.5 KB, 187 views)
File Type: jpg 003.jpg (716.5 KB, 179 views)

Last edited by KatieandDad; 28th April 2012 at 11:01 AM.
  Reply With Quote
Old 28th April 2012, 12:14 PM   #13
diyAudio Member
 
Join Date: Apr 2010
I can't tell if those are similar in design to mine. I'll try to draw up that schematic later.

I've now connected the transformer as per Tekko's advice. Just using one and the same rail for both amps.

Listening now, it sounds considerably better than with the wal wart (not surprisingly), and I can now play quite loud - no clipping. There is quite a bit of 50Hz hum however, but that is probably caused by my sloppy temporary wiring (speaker wires and power wires are crossed). They're hanging loose right now. Will have to find some wood planks to bolt them to, or something.

They appear to sound rather nice, but it is hard to really say, due to the hum, and because I'm only using my rather poor test speakers (nice drivers but poor cabinet). Don't dare to plug in my primary speakers, yet.

This is fun!

EDIT: Could the lower voltage cause hum? There was none with 12V, but there is with 30. It's probably supposed to run at 45-50V.

EDIT2: I tried playing without a pre-amp and just adjusting the volume with the computer. Worked well, sounded better. But more hum! Then when I unplugged the power cord, there was an increasingly loud sizzle sound, kind of when you pour water into a hot frying pan. Freaky! That did not happen when I used the pre-amp, then it would just turn off with a smooth popping sound.

Last edited by Coconuts 500; 28th April 2012 at 12:28 PM.
  Reply With Quote
Old 28th April 2012, 12:25 PM   #14
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
Lower voltage shouldn't cause hum on its own unless you have crap caps. It will however distort badly as it will clip early.

Clipping is bad for speakers so get PSU right before you try good speakers.
  Reply With Quote
Old 28th April 2012, 12:44 PM   #15
Banned
 
Join Date: Jan 2005
From what i can tell, those modules have two 1000F 100V capacitors in series across Vcc and GND, these add up to a total of 500F, nowhere near enuf filtering.
  Reply With Quote
Old 28th April 2012, 12:51 PM   #16
diyAudio Member
 
Join Date: Apr 2010
That's true actually. I didn't think of that. Remembered them as 2200 for some reason, and assumed they were in parallel. 500 - that's ridiculous. What were they thinking?

Puzzling. These are rated at 100V each - why would they be in series?

EDIT: Upon closer inspection, they aren't exactly in series. There's a big resistor (10K, 2 or 3 W), and an LED in between them.

Last edited by Coconuts 500; 28th April 2012 at 12:57 PM.
  Reply With Quote
Old 28th April 2012, 02:05 PM   #17
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaao
Send a message via Yahoo to jacco vermeulen
They're in parallel.
Easy to see, because traces of both sides are visible : + traces of both lytics are connected in parallel by the fuse holder leads.

I've seen these modules before, even recognise the ECN-CPA4 print, few decades ago, for the likes of me can't recall the rest of the story (the moment to jump off a bridge is due).
__________________
The buck stops Here
  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
2sk135 2sj50 akersa Parts 46 2nd May 2013 06:23 PM
2SJ50 and 2SK135 mosfet transistors xecluded Solid State 16 16th April 2009 02:42 PM
sub for 2sj50/2sk135 sasha Solid State 20 27th March 2008 04:28 PM
2sj50/2sk135 jean-paul Swap Meet 0 26th February 2006 10:16 PM


New To Site? Need Help?

All times are GMT. The time now is 09:31 AM.


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