Simple Class D Amplifier

[Tekko]

This is a circuit i came up with this morning, i have just finished building it and it turns out it works well above expectation.

I'm running it from 2x35VDC and the fets(IRFP450) is not even getting warm.

Schematic: http://i.imgur.com/giy22.png

 

[Tekko]

A video: Clocked Class D amplifier - YouTube

 

[Bare]

A combo between Rube Goldberg and Gyro Gearloose.. both would be proud

 

[AP2]

Hi,
i see a big unlinearity on blue wav up side.

 

[Tekko]

It's a child in growth pains, i havent dealt with these triangular wave oscillators in a looong time so im mostly getting sine waves out, maybe LM4562 isent a particularly good choice, even though im only asking it to oscillate at around 100kHz.

 

[apexaudio]

Nice circuit, can you scope triangle oscillator output.

 

[Tekko]

I did, and it was a mix between a triangular wave and a sine wave.

 

[apexaudio]

I did, and it was a mix between a triangular wave and a sine wave.

You can try triangle oscillator from JBL 200kHz with single OP (1/2 TL072).

 

[Tekko]

That, or rework thed values of the resistors in the existing circuit, i lean toward the latter as i doubt i have any 5.6V zeners, i have 7.5V, 10V and i think 12 and 15V.

That jbl circuit kinda reminds me of the circuit of a relaxation oscillator.

 

[stewin]

hi tekko what are the harmonics of your amp ? have you tried hv like +/-80vlts?

 

[Tekko]

I never got that far, i had it runnig on 2x37V when a ground wire came loose and landed straight onto the gate for the high side fet = *POOF* and after that the IR2110 and both IRFP450's were dead.

 

[stewin]

i sure hope you try hi voltage like 90+/- many amps cannot operate with that high voltage.

 

[Tekko]

My plan was to use a 50A 600V IGBT module for the output stage, i alrready tried this an d on 2x38VDC and 500kHz, the module with no heatsing only got slightly warm, the audio part dident worth though as i tried it with transformer coupled gate drive.

I'll resume the work on this this weekend, and i will socket the IR2110 so it can be easily replaced when needed.

 

[stewin]

igbt as class d output stage? but they are very slow .

what voltage do you have in mind?

 

[Tekko]

The old igbts were slow, the modern ones are almost as fast as mosfets.

As i said i ran a modern fairchild transfer molded igbt halfbridge module(http://www.fairchildsemi.com/ds/FP/FP7G50US60.pdf) at 500kHz with 2x38VDC and it only got slightly warm just laying on the table, and that with lousy transformer gate drive and no heatsink.

 

[stewin]

that igbt is great it can make a 3kwts smps with no issues .

 

[Tekko]

This Fairchild IGBT just proved itself, a short piece of thin wire lietrally melted at near max power output, was cranking to near 99% duty cycle when i looked over and saw smoke.

Despite this abuse, the IGBT module was only ever so slightly warm.

 

[Tekko]

A video: Simple Class D amplifier - YouTube

 

[Tekko]

A new video: Feedbackless class d amp pounding it - YouTube

Rail voltages are now 2x60V, but for some reason 30-35V is the max i can get out, even when its clipping and hitting the rails.

The fets remain barely warm to the touch.

 

[luizcpimenta]

You can try triangle oscillator from JBL 200kHz with single OP (1/2 TL072).

Good evening.
You can send me the complete layout of this amplifier?
Thank you.
luizcpimenta@yahoo.com.br
luizcpimenta@gmail.com