DOGC-H by Dr. Jagodic - Page 3

kacernator · 22nd January 2018, 04:46 PM

Quote:

Originally Posted by Machina

Hmm
I wonder so, my power supply is 2x37ac (old trafo on 220V), sometimes its +- 53Vdc. AC lines can show 223-234Vac. Irfd110 has Vds100V, can it be the reason of burning?

Do you have proper heatsink on input mosfets? You should hold you hand on the heatsink, otherwise it is too hot.

Machina · 23rd January 2018, 10:40 PM

Heatsink is not small it, about 70C when playing 2h.
Dont know if it will help me to find the cause why its burning, but, when the amplifier is turned on, then, I turned it off, maybe four seconds have passed, I turned on again, and VUALA finished, burned!

Machina · 06:51 PM

Quote:

Originally Posted by kacernator

Do you have proper heatsink on input mosfets? You should hold you hand on the heatsink, otherwise it is too hot.

80W Hybrid Audio Amplifier!
I will try, and incrase Irfd110 capacitor, maybe it will help for future .
Or add a capacitor to 100k resistor, (input/gnd,150pF), mayby a hi frequency is gaining when Im turning off.

Update.
I forgot to mention, there are two monoblocks, and one that breaks down, the transformer shows 2x37VAC, the other is 2x36V and does not show this propensity of burning irfd110 on input side.

year98 · 12th April 2018, 04:24 PM

Instead of 630/9630, IRF530/9530 can be used?

kacernator · 12th April 2018, 07:55 PM

Quote:

Originally Posted by year98

Instead of 630/9630, IRF530/9530 can be used?

Yes, no problem.

year98 · 12th April 2018, 08:26 PM

Quote:

Originally Posted by kacernator

Yes, no problem.

Thanks a lot. 530/9530 are 100v devices. Is it enough for ±48v?

kacernator · 13th April 2018, 04:20 PM

Quote:

Originally Posted by year98

Thanks a lot. 530/9530 are 100v devices. Is it enough for ±48v?

It should be OK.

year98 · 13th April 2018, 06:29 PM

Quote:

Originally Posted by kacernator

It should be OK.

Thank you.

mgottwa · 09:07 PM

I have a question: After Building my Dogc mk3, I found out it has about
24dB gain. I would like to reduce it to about 12dB. Any advice
which resistor to be changed?

Thank you for advice.

Regards
Michael

mlloyd1 · 9th April 2019, 09:12 PM

To avoid playing with the frequency compensation (which you should do if you adjust the gain by playing around with the feedback resistors), why not just add 100K in series with the input?
With the roughly 100k already there, the gain is chopped in half.
Sure, you'll take a little noise hit, but what's a little noise between friends?

mlloyd1

9th April 2019, 08:57 PM	#29
mgottwa diyAudio Member Join Date: Apr 2015 Location: Stuttgart	I have a question: After Building my Dogc mk3, I found out it has about 24dB gain. I would like to reduce it to about 12dB. Any advice which resistor to be changed? Thank you for advice. Regards Michael Last edited by mgottwa; 9th April 2019 at 09:07 PM.

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23rd January 2018, 10:40 PM	#22
Machina diyAudio Member Join Date: Dec 2010	Heatsink is not small it, about 70C when playing 2h. Dont know if it will help me to find the cause why its burning, but, when the amplifier is turned on, then, I turned it off, maybe four seconds have passed, I turned on again, and VUALA finished, burned!

12th April 2018, 04:24 PM	#24
year98 diyAudio Member Join Date: Jun 2008	Instead of 630/9630, IRF530/9530 can be used?

9th April 2019, 09:12 PM	#30
mlloyd1 diyAudio Member Join Date: Feb 2001 Location: Northern Iliinois	To avoid playing with the frequency compensation (which you should do if you adjust the gain by playing around with the feedback resistors), why not just add 100K in series with the input? With the roughly 100k already there, the gain is chopped in half. Sure, you'll take a little noise hit, but what's a little noise between friends? mlloyd1