Latest project IGBT power amp.

[nigelwright7557]

IGBT power amp 150WRMS in quasi complimentary mode.
Uses NGTB35N65FL2WG IGBT's.
Managed to squeeze into 10cm by 10cm for cheap pcb's from pcbway.
Sounds good.

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

 

[nigelwright7557]

I made a mistake on the pcb.
I have two zobel networks on the output.
Its the way the circuit was drawn that caused the problem.
It just means not fitting two components.

 

[myroslavmm]

Very intresting, can you show your schematic?

 

[AKSA]

Very interesting amp, Nigel, very few take on IGBTs for audio, saying they are too slow.
However, JLH did very well with 2N3055s, and they are a lot faster than that!
Can you perhaps give us any features, and the performance, particularly FFT?

Hugh

 

[nigelwright7557]

Very intresting, can you show your schematic?

Its basically same as class ab quasi amplifier.
CCS and CM on front end then VAS into VBE multiplier.
The output has drivers mje340/350 with Baxandall diode.

It doesn't sound any different to my own design vertical mosfet amp.

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

 

[fmmech_24]

..i'm sorry, but the schematic isn't readable..can you print it as pdf?

..and if anyone is interestet in: (Focal FPS4160 Amplifier with IRG4BC20 TO-220 Devices, still in progress..)

FOCAL_IGBT_Amp_SCH.pdf - DocDroid
FOCAL FPS LINE_sch.pdf - DocDroid
FOCAL FPS LINE_sch_1.pdf - DocDroid

 

[nigelwright7557]

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

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

 

[nigelwright7557]

Very interesting amp, Nigel, very few take on IGBTs for audio, saying they are too slow.
However, JLH did very well with 2N3055s, and they are a lot faster than that!
Can you perhaps give us any features, and the performance, particularly FFT?

Hugh

Switch on and off times are around 70nS.

 

[rsavas]

Actually amazing devices.

Switch on and off times are around 70nS.

For the IGBT device itself, how about the amp?
The only freq compensation that I see is C5. How's the transient response, THD etc?

Very strange way to draw a resistor, why so long and narrow, this is your default R symbol? personnel preference? Seems mixed up, using some IEC and ANSI symbol representations for resistors/pots. I know it is a bit of nit-picking but serves as comments only, from a guy who has used many different eCad systems over the years.

Cheers

 

[nigelwright7557]

I must admit I haven't done any tests on it yet.

The resistor symbol is done that way so the component reference and value lay inside the bounds of the component so there are no misunderstandings.
In around 3000 sales I have only had one customer criticise that.
However the component can be changed if so required by the user.
Nothing is set in stone.

 

[rsavas]

The resistor symbol is done that way so the component reference and value lay inside the bounds of the component so there are no misunderstandings.

I see your point for the R symbol, but that does not work for the C symbol, certainly not universal.
Being that large it is cumbersome if you have lots of them as in say a R pack with individual component parts(annotations).

In around 3000 sales I have only had one customer criticize that.

I guess I have a lot more experience in evaluation ECad systems than most do. It does not take me long to find particularities in the way they operate.

I was evaluation diptrace of late, found out they do not even have a pcb comp placement outline layer, comps can over lap with no drc violation= nuts, so much for DFM constraints.

 

[nigelwright7557]

I have to admit that my software was originally written in around 1990 after using EasyPC so a lot of the symbols, key presses and terminology are the same as EasyPC.

I have made around 150 pcb's with the software so have had lots of time to debug and add new functions as the need arose.

 

[nigelwright7557]

I have used numerous pcb cad packages free and paid for.
That's where I "borrow" some of my ideas from.

My software does have some auto placing routines that you don't often see in low cost CAD software.

 

[traderbam]

Switch on and off times are around 70nS.

Just how fast does a transistor need to be to reproduce 20kHz?
Oh negative feedback...

The thing is the data sheets don't show the equivalent of ft for IGBTs, presumably because no one uses them in linear mode. Except some crafty persons. What we need is a graph of transconductance vs frequency.

Why did you use a "Baxandall diode"?

 

[nigelwright7557]

Why did you use a "Baxandall diode"?

The diode is there to limit the voltage lost at the resistors in cases of high negative output currents. It also makes the transition a little more symmetric, having two PN junctions for both the negative and positive half - at least for higher current.

 

[traderbam]

Two PN junctions?

I love these bruiser IGBTs. "Typical applications: welding".

 

[nigelwright7557]

This one is a bit of a beast.

http://uk.rs-online.com/web/p/igbt-transistors/8080234/

 

[Bigun]

Very interesting amp, Nigel, very few take on IGBTs for audio, saying they are too slow.
However, JLH did very well with 2N3055s, and they are a lot faster than that!
Can you perhaps give us any features, and the performance, particularly FFT?

Hugh

I've found my JLH'69 doesn't reach the level of audio enjoyment I anticipated. I use 2N3055H, these are the really slow ones. I use 4 in parallel too, because they have terrible beta-droop. I bet JLH would have those 2N3055's in the trash bin were he here today

 

[nigelwright7557]

I used to run a mobile disco in the 1980's and used the Maplin 225WRMS 2N3055/MJ2955 amplifier. Even though the rail voltages were a bit high for the devices it was very loud and sounded very good.
I liked to play loud so it took some stick for years and never let me down.

 

[rsavas]

I have used numerous pcb cad packages free and paid for.
That's where I "borrow" some of my ideas from.
My software does have some auto placing routines that you don't often see in low cost CAD software.

Nothing wrong with re-using/borrowing ideas from other vendors.
Have you used Zuken? Nice to see they are still around
I never used auto place. Took too long to set up the constraints, just to have to go and fix it again. But you still need placement boundaries for DFM process rules.

I have made around 150 pcb's with the software so have had lots of time to debug and add new functions as the need arose.

Of these designs, how many were mass produced? auto-insertion, pick n place, ICT tested?