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Maplin Mosfet Amplifier Ga28f construction thread
Maplin Mosfet Amplifier Ga28f construction thread
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Old 8th June 2014, 10:03 PM   #1
jamesfeline is offline jamesfeline  United Kingdom
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Default Maplin Mosfet Amplifier Ga28f construction thread

Hi

Please find a few pics of my new Maplin 100w Mosfet amplifier construction thread .. All parts are new old stock with original transistors, but all capacitors are new, just a little bit of nostalgia from the past !!

Both amps will be mono blocks ..

best regards Nick
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Old 8th June 2014, 10:23 PM   #2
jamesfeline is offline jamesfeline  United Kingdom
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Hi

Also includes rare original power supply board, I will be using one for each amplifier with dedicated transformers

regards

Nick
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Old 12th June 2014, 10:02 PM   #3
jamesfeline is offline jamesfeline  United Kingdom
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Default More pics

Hello

One power amp board nearly complete .. all new components etc

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

and one of the PSU board which is very rare

Click the image to open in full size.

regards

NIck
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Old 12th June 2014, 10:30 PM   #4
KatieandDad is offline KatieandDad  United Kingdom
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I've got the original article here if you would like to add it.
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Old 13th June 2014, 12:21 AM   #5
nigelwright7557 is offline nigelwright7557  United Kingdom
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Quote:
Originally Posted by KatieandDad View Post
I've got the original article here if you would like to add it.
Me too.

Just bought one of these amps off ebay about 2 weeks ago.
It wasn't even built up, still in kit form.
So I built it up and it worked first time.
Sounds really good.
Click the image to open in full size.
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Old 13th June 2014, 12:33 AM   #6
nigelwright7557 is offline nigelwright7557  United Kingdom
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Here's another Maplin amp I bought and repaired.
Click the image to open in full size.
Click the image to open in full size.
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Old 13th June 2014, 08:58 PM   #7
nigelwright7557 is offline nigelwright7557  United Kingdom
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There are a couple of these amps on ebay at the moment.
Starting price 30 + p+p

Not my auction.
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Old 13th June 2014, 09:03 PM   #8
jamesfeline is offline jamesfeline  United Kingdom
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Hi

I am having some new PCB's being made, 2 oz bare copper Fr4 boards .. I generated my own gerber files to update the original layout.

If anyone wants any let me know .. as the examples on ebay are over priced, I can make them very much cheaper with modern components .. however I do have a stock pile of the original transistors ... luckily for me

regards

Nick
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Old 13th June 2014, 09:11 PM   #9
nigelwright7557 is offline nigelwright7557  United Kingdom
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I built my first one around 1980.
It worked fine but wasn't loud enough for disco.
So I bought the 225WRMS bipolar amp kit and that was great.

I have just redesigned the 100 watt mosfet amp to work with hexfets.
The circuit is basically the same but with source resistors, irfp240/9240 and a Vbe multiplier with thermal feedback.
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Old 13th June 2014, 11:53 PM   #10
nigelwright7557 is offline nigelwright7557  United Kingdom
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Quote:
Originally Posted by jamesfeline View Post
Hi

I am having some new PCB's being made, 2 oz bare copper Fr4 boards .. I generated my own gerber files to update the original layout.

If anyone wants any let me know .. as the examples on ebay are over priced, I can make them very much cheaper with modern components .. however I do have a stock pile of the original transistors ... luckily for me

regards

Nick
Maplin amps on ebay are as rare as hens teeth.
I dropped out at 75 for a 225WRMS Maplin amp.

However, I picked up a pair for peanuts that were faulty a few months later.
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