UCD 25 watts to 1200 watts using 2 mosfets

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#381
It's by far not as bad as you imagine. And his imagination tells a lot about how things are going in life for somebody...

The protection that tripped was in the power supply and involves a current sense transformer with 200 turns and inherent antenna properties. Ironically, this transformer is working at mains frequency, it's a linear circuit involving op-amps and a PIC. It's calling for a couple of ferrite beads and caps to avoid rectification of ambient RF in the input LTP of a bipolar op-amp.

Protection against wrong oscillation modes is very useful as the product ages. Imagine the result of an open feedback resistor or a cold joint somewhere. Bang! or immediate shutdown.

btw: No, it does not make funny noises unless the phone is placed crazy close to the modulator 😀

btw2: That's without an enclosure, bare pcbs on a wood bench 😉
 
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#385
This is the schematic for the delayed poweron board:
delayedon.png
 
#386
It have turned out im still below 200kHz, had moved a knob on the scope without knowing it, so that it looked like the frequency had increased to 300kHz.

And now i noticed there were too many resistors in the input part so when i removed those i actually did climb to 250kHz, and it sounds like it improved ther sonics as well.
 
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#388
AP2, i used the enable/disable in the current source like in the philips ucd schematic: http://www.nxp.com/documents/user_manual/UM10155.pdf

pad 3 and 4 in my schematic, tho i guess using the sd pin on the IR2010 would yield similar results, i chose what i chose because i dident feel like digging up the ground plane around the SD pin.
basicclassdsch11-1.png


And here are two new pics of the updated startup delay:

Amp in standby, no oscillation:
010.jpg


Amp active:
009.jpg


The white led was supposed to be yellow, picked the wrong bag.😱
 
#394
Tekko said:
AP2, i used the enable/disable in the current source like in the philips ucd schematic: http://www.nxp.com/documents/user_manual/UM10155.pdf

pad 3 and 4 in my schematic, tho i guess using the sd pin on the IR2010 would yield similar results, i chose what i chose because i dident feel like digging up the ground plane around the SD pin.
basicclassdsch11-1.png


And here are two new pics of the updated startup delay:

Amp in standby, no oscillation:
010.jpg


Amp active:
009.jpg


The white led was supposed to be yellow, picked the wrong bag.😱
Click to expand...

Hi Tekko,
I did not completely read the posts but try these;
i) put an electrolitic cap parallel to R6 for delayed turn on, also disconnecting R2 from gnd can be used as disable function.
ii)Or put an electrolytic cap from vdd to SD pin of IR2112 and let the SD pin go to -24v with a resistor. For both i&ii you need to make some calculation for cap and/or resistor values.
iii)To adjust the offset use offset balance fuction already supplied on LM311 (pins 5,6).

Regards
FH
 
#398
The audio source is my computer, i mix the channels into mono, then run the mono signal through two opamps, one inverting and the other non inverting.

After that the balanced signal travels thround an old ethernet cable to the amp, around 7 meters worth, at the amp its received by the buffer that i chose to have an input impedance of 18kohm.

There might be a slight improvement in audio quality.
 
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