Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

Maplin Mosfet Amplifier Ga28f construction thread
Maplin Mosfet Amplifier Ga28f construction thread
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 16th February 2018, 09:56 AM   #91
jamesfeline is offline jamesfeline  United Kingdom
diyAudio Member
 
jamesfeline's Avatar
 
Join Date: Feb 2006
Location: Essex
now with the heat sink mounted .. please note this has not been finally completed so the heat sink is just a trail fitment exercise .. but will most probably go with this set up
Attached Images
File Type: jpg IMG_0623.jpg (458.3 KB, 335 views)
File Type: jpg IMG_0624.jpg (400.0 KB, 333 views)
File Type: jpg IMG_0625.jpg (441.2 KB, 319 views)
File Type: jpg IMG_0626.jpg (588.9 KB, 316 views)
File Type: jpg IMG_0627.jpg (420.7 KB, 305 views)
File Type: jpg IMG_0628.jpg (480.1 KB, 100 views)
  Reply With Quote
Old 16th February 2018, 09:59 AM   #92
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
Nice, I attached a phono socket directly to the original amp boards, I don't know why it isn't done more often. Have you tried using Belleville washers for transistor mounting? Belleville washer - Wikipedia
  Reply With Quote
Old 16th February 2018, 10:28 AM   #93
jamesfeline is offline jamesfeline  United Kingdom
diyAudio Member
 
jamesfeline's Avatar
 
Join Date: Feb 2006
Location: Essex
Quote:
Originally Posted by scottjoplin View Post
Nice, I attached a phono socket directly to the original amp boards, I don't know why it isn't done more often. Have you tried using Belleville washers for transistor mounting? Belleville washer - Wikipedia
well done .. never knew there was such a thing as a Belleville washer ? thanks for the head up
  Reply With Quote
Old 15th June 2019, 10:25 AM   #94
jamesfeline is offline jamesfeline  United Kingdom
diyAudio Member
 
jamesfeline's Avatar
 
Join Date: Feb 2006
Location: Essex
Hello .. have not been around for a while as have been very ill .. but on the road to recovery, any way while at home I got bored so decided to develop the gerber files for the maplin mosfet amplifier as really fond of the design and sound quality .. retro years etc in my youth
Attached Files
File Type: pdf mosfet-amp-CR.pdf (27.9 KB, 68 views)
File Type: pdf mosfet-amp-SS.pdf (24.4 KB, 58 views)
File Type: pdf mosfet-amp-dr.pdf (23.5 KB, 47 views)
File Type: pdf mosfet-amp-TR.pdf (17.9 KB, 51 views)
  Reply With Quote
Old 15th June 2019, 10:36 PM   #95
Mark Tillotson is offline Mark Tillotson
diyAudio Member
 
Join Date: May 2018
Location: Cambridge UK
This thread reminded me, I reworked the Maplin amp using a custom smaller PCB - I had a stock of a few pairs of 2SK135/2SJ50's and the small signal transistors from way back to find a use:
Click the image to open in full size.
The output inductor is under the board as are the gate protection diodes & zeners.
  Reply With Quote
Old 16th June 2019, 07:39 AM   #96
Ian Finch is offline Ian Finch  Australia
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour, NSW
Quote:
Originally Posted by Mark Tillotson View Post
This thread reminded me, I reworked the Maplin amp using a custom smaller PCB .....
I imagine from the layout and heatsink sizes, that there was no pretence that this version would still deliver 100W reliably .
__________________
If only I had listened....
  Reply With Quote
Old 16th June 2019, 09:51 AM   #97
jamesfeline is offline jamesfeline  United Kingdom
diyAudio Member
 
jamesfeline's Avatar
 
Join Date: Feb 2006
Location: Essex
Quote:
Originally Posted by Mark Tillotson View Post
This thread reminded me, I reworked the Maplin amp using a custom smaller PCB - I had a stock of a few pairs of 2SK135/2SJ50's and the small signal transistors from way back to find a use:
Click the image to open in full size.
The output inductor is under the board as are the gate protection diodes & zeners.
Hello Mark ... that is indeed small, did your newly designed PCB work all OK? just out of interest did you make any changes to the design and component values? or transistor types? just curious to know

Best regards
  Reply With Quote
Old 16th June 2019, 11:40 AM   #98
Mark Tillotson is offline Mark Tillotson
diyAudio Member
 
Join Date: May 2018
Location: Cambridge UK
Quote:
Originally Posted by Ian Finch View Post
I imagine from the layout and heatsink sizes, that there was no pretence that this version would still deliver 100W reliably .

100W continuous, no I suspect not, but its adequate for normal use I think, I tend not to listen to pure sine waves at 100% level (dub reggae perhaps being an exception!). The boards were tested to 100W briefly to check stability, and are awaiting a nice case plus preamp.
  Reply With Quote
Old 17th June 2019, 06:45 AM   #99
Ian Finch is offline Ian Finch  Australia
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour, NSW
Would you care to tell us what bias level you decided on?
__________________
If only I had listened....
  Reply With Quote
Old 17th June 2019, 03:11 PM   #100
Mark Tillotson is offline Mark Tillotson
diyAudio Member
 
Join Date: May 2018
Location: Cambridge UK
Its the exact same circuit, just smaller parts, standard bias is 100mA IIRC
  Reply With Quote

Reply


Maplin Mosfet Amplifier Ga28f construction threadHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Maplin 100w mosfet amplifier built from 1980 kit nigelwright7557 Solid State 34 11th December 2015 12:40 AM
Maplin 100W mosfet amplifier - power supply problem HBrunt Solid State 32 3rd December 2013 07:11 AM
Maplin 1kw mosfet amp build thread jamesfeline Solid State 8 23rd June 2012 02:51 PM
maplin mosfet GA28F upgrades? Gravenstede Solid State 5 17th March 2008 06:34 PM
GA28F Mosfet Amp hungeryhippie Solid State 7 5th May 2007 03:57 AM


New To Site? Need Help?

All times are GMT. The time now is 07:02 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki