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Old 22nd July 2008, 11:24 PM   #1
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Default "half" Power Amp...

Hi dears and DIY builders

This is my last power amplifier. It's not a BIG POWER, but there is a +45V/-45V regulated SMPS, and 3 + 3 output transistors (2SA1943/2SC5200) by side.
Anohter side is about construction, Like Freddie Mercury say: "It's a hard life".
Comments are always welcome.

Thank you very much.

CHACALPOWERS
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Old 22nd July 2008, 11:25 PM   #2
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another pic
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Old 22nd July 2008, 11:26 PM   #3
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another pic2
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Old 22nd July 2008, 11:28 PM   #4
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heatsink waiting...
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Old 23rd July 2008, 09:53 AM   #5
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Please tell us something more about the SMPS.
Maybe you could post the schematics?

Enrico
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Old 23rd July 2008, 11:03 PM   #6
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Default About SMPS

Hi Enrico

My SMPS is based on this schematics:

http://i186.photobucket.com/albums/x...G3525smps1.jpg

The output regulation I change to 4N35 plus 2 IN4755 zener diode (43V) because I don't like opamp for output regulated.

Regards

Sandro
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Old 24th July 2008, 01:47 PM   #7
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Sandro

Do you still use clean secondary ground for SG3525 and other circuitry?
Seems to me, that when using optocoupler you can reference the whole driving circuit to mains neautral.

Do you use any snubbers at half bridge mosfets?

Regards
Adam
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Old 24th July 2008, 10:33 PM   #8
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Hi Adam

Excuse se by my bad english.
I don't understand what is " clean secondary"...?
And "snubbers" are ferrite beams in mosfet gates?

About the opto, I only connect it is +/-output, less ground.
The ground for KA3525 comes from a small transformer (200mA).

The LIVE GND don't is together with it, it's all isolated.

Regards

Sandro (from Brazil)
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Old 26th July 2008, 02:42 AM   #9
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Sandro,

Nice job on the finished project!

Interesting output feedback sensing, the way the op-amps are employed. Question: Do you retain the op-amps and connect them to the opto, or just replace them wit the opto? I like the fact that you monitor both the (+) and (-) outputs. I have seen many opto-monitored outputs just monitor the (+) rail, and feel that symmetric monitoring offers a superior performance to the (+)-only mnitoring. Just my two-cents.


Kind Regards,

Steve
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Old 26th July 2008, 08:48 AM   #10
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The bad thing about the original schematic is that the gate driving transformer and current sense transformer are safety transformers at the same time.
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