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.

Latest project 100 watt biplolar amp based on 1980's Maplin disco amplifier
Latest project 100 watt biplolar amp based on 1980's Maplin disco amplifier
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, 09:12 PM   #11
nigelwright7557 is offline nigelwright7557  United Kingdom
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by jamesfeline View Post
Hi Nigel

Is the PCB fully debugged ? all works OK ? also any reason why you only used one pair of output transistors instead of 4 like the original ... I would be interested in buying a few PCB from you .. any chance of some PCB pictures ?

best regards
The circuit works and sounds good.
I thought 2 To3's would be easier to drill than 4.
100WRMS is good for most peoples use.

I have some pcb's unpopulated if you want any.
£5 for each pcb and £2-20 first class signed for UK p+p by paypal.
I will include parts list, wiring diagram and circuit diagram.

Click the image to open in full size.
__________________
PCBCAD51 pcb design software. 2018 version out now with lower prices >> http://www.murtonpikesystems.co.uk

Last edited by nigelwright7557; 16th February 2018 at 09:23 PM.
  Reply With Quote
Old 16th February 2018, 10:27 PM   #12
jamesfeline is online now jamesfeline  United Kingdom
diyAudio Member
 
jamesfeline's Avatar
 
Join Date: Feb 2006
Location: Essex
ok great ... also can we have a 4 output transistor version ? how is the best way to purchase please PM me or put on EBAY ?
  Reply With Quote
Old 16th February 2018, 10:50 PM   #13
nigelwright7557 is offline nigelwright7557  United Kingdom
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by jamesfeline View Post
ok great ... also can we have a 4 output transistor version ?

I already have a four transistor design and pcb laid out.
I don't have any unpopulated pcb's at the moment.
__________________
PCBCAD51 pcb design software. 2018 version out now with lower prices >> http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 16th February 2018, 11:31 PM   #14
nigelwright7557 is offline nigelwright7557  United Kingdom
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by jamesfeline View Post
ok great ... also can we have a 4 output transistor version ? how is the best way to purchase please PM me or put on EBAY ?
PM sent.
__________________
PCBCAD51 pcb design software. 2018 version out now with lower prices >> http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 17th February 2018, 11:42 PM   #15
nigelwright7557 is offline nigelwright7557  United Kingdom
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
I had a look through the original Maplin disco amp write up and the bias is set by measuring power supply current and it should be 70mA.
But that's with four output transistors.

Here is a page that I made up about the amp, the Maplin article is in pdf form right at the bottom of the page.

I am finding my amp sounds ok and doesn't have crossover distortion even at zero bias voltage.

Maplin 150 / 225 watts RMS amplifier from the 1980's.
__________________
PCBCAD51 pcb design software. 2018 version out now with lower prices >> http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 18th February 2018, 01:43 AM   #16
nigelwright7557 is offline nigelwright7557  United Kingdom
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
I built up another pcb today.
This time I used 2N3055 and MJ2955 as output transistors as per original design by Maplin.
I was worried they wouldn't have enough gain but my semiconductor analyser says 2N3055 has gain of 65 and MJ2955 has gain of 273 !

Sounds ok. So got my self a retro amp.
__________________
PCBCAD51 pcb design software. 2018 version out now with lower prices >> http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 18th February 2018, 08:48 AM   #17
jamesfeline is online now jamesfeline  United Kingdom
diyAudio Member
 
jamesfeline's Avatar
 
Join Date: Feb 2006
Location: Essex
well done Nigel .....
  Reply With Quote
Old 18th February 2018, 08:58 AM   #18
suzyj is offline suzyj  Australia
diyAudio Member
 
suzyj's Avatar
 
Join Date: Jan 2006
Location: Western Australia
I see a lot of hatred for the 2955/3055? What’s with that? I reckon they’re possibly the most important transistors ever - used in absolutely everything.
__________________
http://www.suzyj.net
  Reply With Quote
Old 18th February 2018, 09:03 AM   #19
jamesfeline is online now jamesfeline  United Kingdom
diyAudio Member
 
jamesfeline's Avatar
 
Join Date: Feb 2006
Location: Essex
Quote:
Originally Posted by suzyj View Post
I see a lot of hatred for the 2955/3055? What’s with that? I reckon they’re possibly the most important transistors ever - used in absolutely everything.
Exactly ..
  Reply With Quote

Reply


Latest project 100 watt biplolar amp based on 1980's Maplin disco amplifierHide 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
Latest project usb and mic valve mixer for a mobile disco. nigelwright7557 Instruments and Amps 8 3rd August 2016 11:20 PM
Maplin 100w mosfet amplifier built from 1980 kit nigelwright7557 Solid State 34 11th December 2015 12:40 AM
Latest project update to Maplin 50WRMS amplifier. nigelwright7557 Solid State 6 29th August 2014 11:06 PM
Latest project, valve stereo disco mixer nigelwright7557 Instruments and Amps 9 7th July 2014 09:47 AM
Latest project, 80 watt valve amplifier nigelwright7557 Tubes / Valves 13 22nd June 2013 09:32 PM


New To Site? Need Help?

All times are GMT. The time now is 01:45 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki