"half" Power Amp...

CHACALPOWERS · 22nd July 2008, 11:24 PM

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

CHACALPOWERS · 22nd July 2008, 11:25 PM

another pic

CHACALPOWERS · 22nd July 2008, 11:26 PM

another pic2

CHACALPOWERS · 22nd July 2008, 11:28 PM

heatsink waiting...

DoctorC · 23rd July 2008, 09:53 AM

Please tell us something more about the SMPS.
Maybe you could post the schematics?

Enrico

CHACALPOWERS · 23rd July 2008, 11:03 PM

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

darkfenriz · 24th July 2008, 01:47 PM

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

CHACALPOWERS · 24th July 2008, 10:33 PM

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)

N-Channel · 26th July 2008, 02:42 AM

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

darkfenriz · 26th July 2008, 08:48 AM

The bad thing about the original schematic is that the gate driving transformer and current sense transformer are safety transformers at the same time.

23rd July 2008, 11:03 PM	#6
CHACALPOWERS diyAudio Member Join Date: Jul 2007	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

26th July 2008, 02:42 AM	#9
N-Channel diyAudio Member Join Date: Mar 2003 Location: Sol System	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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23rd July 2008, 09:53 AM	#5
DoctorC diyAudio Member Join Date: Dec 2004 Location: Warszawa	Please tell us something more about the SMPS. Maybe you could post the schematics? Enrico

24th July 2008, 01:47 PM	#7
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	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

24th July 2008, 10:33 PM	#8
CHACALPOWERS diyAudio Member Join Date: Jul 2007	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)

26th July 2008, 08:48 AM	#10
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	The bad thing about the original schematic is that the gate driving transformer and current sense transformer are safety transformers at the same time.