Really Nutty Class D (RNCD)

Duo · 6th February 2007, 08:41 AM

Here I present something to make all of the class D amplifier people turn green.

Those engineer types will see what's going on here. If you don't get how this thing works, ask and I'll come back with a reply. It's pretty simple though.

IVX · 6th February 2007, 04:38 PM

Wow, one more NCD?

Duo · 6th February 2007, 07:11 PM

I can't believe I indicated a P-channel in the diagram.

For the record, it is N-channel.

darkfenriz · 6th February 2007, 08:37 PM

what's the diode for?

Duo · 6th February 2007, 09:03 PM

The diode rectifies the output of the switching driver. If it was not there, the device would be trying to switch 10V at 60KHz into the cap and load.... Not good. (This is a switching amplifier, not linear.)

darkfenriz · 6th February 2007, 09:07 PM

So if I understand correctly you've built a VCO and output diode works as a FM-discriminator, is it right?

Duo · 6th February 2007, 09:10 PM

No.

This works on duty cycle.

The average amount of power in the inductor is controlled by pulse width, and to some extent, frequency.

darkfenriz · 6th February 2007, 09:37 PM

OK, I think I got it...
You called it classD/A because it is both PWM and ineffifient?

Duo · 7th February 2007, 12:12 AM

Well, it's probably about twice as efficient as a typical class A of the same topology.

What you see here is a class D stage acting as the upper transistor of the class A stage.

The resistor acts as the class A stage's load in order to pull down and do the other half of the wave.

theAnonymous1 · 7th February 2007, 12:48 PM

I have 3 questions......

1) Can I mod this with better input caps?

2) What kind of speaker cable should I use?

3) Can you recommend me a power supply?

6th February 2007, 08:41 AM	#1
Duo diyAudio Member Join Date: Jun 2002 Location: Victoria, BC, Canada	Really Nutty Class D (RNCD) Here I present something to make all of the class D amplifier people turn green. Those engineer types will see what's going on here. If you don't get how this thing works, ask and I'll come back with a reply. It's pretty simple though.

6th February 2007, 04:38 PM	#2
IVX diyAudio Member Join Date: Jul 2003 Location: Everywhere (Buddhist's context)	Wow, one more NCD? __________________ Best regards, E1.

7th February 2007, 12:48 PM	#10
theAnonymous1 diyAudio Member Join Date: Feb 2004 Location: Anonymityville	I have 3 questions...... 1) Can I mod this with better input caps? 2) What kind of speaker cable should I use? 3) Can you recommend me a power supply? __________________ "If you don't like funerals don't kick sand in Ninja's face." - Ninja

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6th February 2007, 07:11 PM	#3
Duo diyAudio Member Join Date: Jun 2002 Location: Victoria, BC, Canada	I can't believe I indicated a P-channel in the diagram. For the record, it is N-channel.

6th February 2007, 08:37 PM	#4
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	what's the diode for?

6th February 2007, 09:03 PM	#5
Duo diyAudio Member Join Date: Jun 2002 Location: Victoria, BC, Canada	The diode rectifies the output of the switching driver. If it was not there, the device would be trying to switch 10V at 60KHz into the cap and load.... Not good. (This is a switching amplifier, not linear.)

6th February 2007, 09:07 PM	#6
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	So if I understand correctly you've built a VCO and output diode works as a FM-discriminator, is it right?

6th February 2007, 09:10 PM	#7
Duo diyAudio Member Join Date: Jun 2002 Location: Victoria, BC, Canada	No. This works on duty cycle. The average amount of power in the inductor is controlled by pulse width, and to some extent, frequency.

6th February 2007, 09:37 PM	#8
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	OK, I think I got it... You called it classD/A because it is both PWM and ineffifient?

7th February 2007, 12:12 AM	#9
Duo diyAudio Member Join Date: Jun 2002 Location: Victoria, BC, Canada	Well, it's probably about twice as efficient as a typical class A of the same topology. What you see here is a class D stage acting as the upper transistor of the class A stage. The resistor acts as the class A stage's load in order to pull down and do the other half of the wave.

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