My discrete class d project

[nigelwright7557]

Just started on a new project, a class d discrete approach.

Uses triangle wave generator, comparator, xor phase splitter and irs2113 hi/lo side switch.

Still in the testing stage.

An externally hosted image should be here but it was not working when we last tested it.

 

[nigelwright7557]

1

 

[nigelwright7557]

Circit diagram.
A bit small due to screen capture.

An externally hosted image should be here but it was not working when we last tested it.

 

[nigelwright7557]

Still testing.

Got the square wave and ramp working cleanly by adjusting components.

Designed improved level translator from output of comparator to xor gates.
This works cleanly now.

At this point it outputs sound althogh with a little more noise than i would like.
Found tweaking the DC offset improved the noise situation.

Output MOSFETs were getting warm so changed gate resistors from 10R to to 56R now they stay cold.

 

[savu]

can you provide a readable schematic?

regards,
savu

 

[nigelwright7557]

can you provide a readable schematic?

regards,
savu

Thats the best i can do without chopping it up into quarters and then it would be meaning less.

My earlier message explains all the stages.
Ramp generator and audio input, comparator, xor phase splitter, hi/lo side switch into irfb4019 mosfets.

Its pretty basic really. Sadly takes more components than a 2092 circuit but what components it uses are very cheap. The inductor is the most expensive part then the £2-50 IRS2113.

 

[savu]

Here is a similar project with discrete parts,

+/-45Vdc supply, 150W RMS into 4 ohm, 250khz, 0.31% THD @ max power, 1.6W dissipated per Mos Fet.

It only exists in LTspice, I never built it.

Regards,
savu

 

[Th3 uN1Qu3]

It only exists in LTspice, I never built it.

Well then would you mind if i build it? However i'll use higher supply rails and two pairs of MOSFETs, i need 200-300W on 8 ohms.

 

[savu]

I wouldn't mind.

tell me the exact configuration and the parts that you intend to use in order to redesign it for you're specific needs.

regards,
savu

 

[Th3 uN1Qu3]

I'll have to examine the schematic more thoroughly - i'll do so in the weekend.

 

[nigelwright7557]

Spent a bit more time getting the noise floor down.
Got thrown a bit by my Mp3 player as its power supply was putting out a bit of noise.

Currently running the amplifier open loop with zero feedback and it sounds very good.

Designing a proper pcb at the moment.

 

[savu]

What PCB software do you use?

At the moment I'm trying to make a small PCB with Altium and it's my first time with Altium so wish me luck .

regards,
savu

 

[nigelwright7557]

What PCB software do you use?

At the moment I'm trying to make a small PCB with Altium and it's my first time with Altium so wish me luck .

regards,
savu

I use PCBCAD40 which I wrote myself in the 1990's.
I converted it to Windows a few years back.
It is very similar to EasyPC and uses a lot of the same key presses.

 

[nigelwright7557]

Got my pcb through for my discrete class d amplifier.

AAAAARRRRRRGGGGGHHHHH got 2 pins swapped on my op amp !!!!!
Hence the two flying leads.

An externally hosted image should be here but it was not working when we last tested it.

 

[balaboo]

Er, I thought your design was going to be DISCRETE ???
I am looking for a ClassD schematic that uses discrete transistors and common opamps.

 

[nigelwright7557]

Er, I thought your design was going to be DISCRETE ???
I am looking for a ClassD schematic that uses discrete transistors and common opamps.

I have done both a discrete and a 2092 amplifiers.

Both work very well.

Discrete version.

An externally hosted image should be here but it was not working when we last tested it.

 

[nigelwright7557]

Er, I thought your design was going to be DISCRETE ???
I am looking for a ClassD schematic that uses discrete transistors and common opamps.

I meant discrete as in no single chip solution.

The semi discrete version works very well open loop.
Sadly it will probably get shelved as the 2092 is a single chip solution and uses less components.

 

[luka]

Does it work already?

 

[nigelwright7557]

Does it work already?

Yes it works fine.

 

[mnemneth]

Thats the best i can do without chopping it up into quarters and then it would be meaning less.

My earlier message explains all the stages.
Ramp generator and audio input, comparator, xor phase splitter, hi/lo side switch into irfb4019 mosfets.

Its pretty basic really. Sadly takes more components than a 2092 circuit but what components it uses are very cheap. The inductor is the most expensive part then the £2-50 IRS2113.

I reckon Savu means the same as I'm going to say.

Can you show your circuit diagram with a WHITE background, not black, please.

It's a complete pain in the eyeballs to examine, as you have it.

Sandy