Elektor Crescendo from cadsoft.de

[haseeb]

Hi ,

I am in process of building the Elektor Crescendo amplifier.

I used the eagle board availalable at ftp://ftp.cadsoft.de/eagle/userfiles...s/diycres.brd.

following is a brief story about my project.

This is my first project from scratch(etching the board).

I some have managed to collect the all matching components as per the board and few near matching components.
I used all matching active components and few near matching passive components.

I am experimenting with low power version by using single pair of mosfets j162/k1058 from hitachi.

My multimeter shows on the baord as 28 to 29 plus and minus volts.

when I first powered the board and I did not dare to connect the power mosfets did some some simulations at mje340/mje350 bjit's,I found ac voltage flactuation from .02 to 13 volts then proceeded to power the mosfets thinking my mosfet driver stage is perfect.

When I powered the output stage the output resistors were heating to cup a tea.

Then I disconnected resistors to the output both sides N and P channel and checked the dc voltage and I realized I bought a blown MOS k1058 which was giving 22 volts when no gate voltage is applied.

Then I bought another k1058 which looked a genuine and powered ,this time every thing looked stable no too much heat dissipation.

But my problem is my mosfets does not amplify.

From my multimeter I see the gate and source volatges are same .

Did I again blowed the mosfets ?.

suggessions are appriciated, I am behind it for last 15 days(day and night).

[haseeb]

It looks I asked a dry query or a repeating story,no one responded to my last post.

Any way I found where I was doing the mistake.

I rectified it by a suggession found from the diyers in some forum.

I was switching the fets to the maximum, when I am powering my board by biasing at 0ohms and consequently frying the fets.

When I adjusted bias to some 500ohms my board became stable.

Now I am able to get amplified signal but I still have a query.

I could get peak 1 amp at 10hms from my prototype but I could not see any huge variation of signal at the source, while I could see a vairiation of 0 to 13 mv at gate. And the same volatge is showing in my multimeter 0-13 v.
How much wattage I am getting from my board ? how can I caliculate this ?.

[stewin]

did you have any measurements of thd