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Old 13th March 2013, 11:44 AM   #2271
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Originally Posted by gaborbela View Post
Hello
What is the purpose (function) of the BD249C BD250C transistors in the circuit.
They form a floating separate power supply for the input, VAS and driver section of the amp. The telos 1000/2500 models uses separate full wave bridge rectifliers in this position instead.
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Old 13th March 2013, 11:49 AM   #2272
jaycee is offline jaycee  United Kingdom
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The BD249/250 form regulators which are used to power the input and VAS stages of the amp. A voltage doubler followed by a regulator is used to provide a slightly higher voltage to the first stages, presumably to reduce noise and to allow the outputs to be driven closer to the rails.
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Old 13th March 2013, 11:49 AM   #2273
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Thank you!
Greetings Gabor
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Old 14th March 2013, 03:34 PM   #2274
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Yes, these transistors are there to isolate the power supply ripple and voltage variations from the output power stage. The capacitors on their bases are "Beta multiplied" for the low signal stages.

Roberto
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Old 22nd March 2013, 06:49 AM   #2275
oiphy is offline oiphy  Norway
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protection part:

C1,C2 220uF volt rating? low esr?
C3 1uF volt rating?

thanks
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Old 22nd March 2013, 01:05 PM   #2276
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Originally Posted by oiphy View Post
protection part:

C1,C2 220uF volt rating? low esr?
C3 1uF volt rating?

thanks
The original design used 220uF/10V non low ESR and 1uF/63V. This may be to low voltage if the mosfets blows.
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Old 22nd March 2013, 11:09 PM   #2277
oiphy is offline oiphy  Norway
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Originally Posted by tommy1000 View Post
The original design used 220uF/10V non low ESR and 1uF/63V. This may be to low voltage if the mosfets blows.
thank you
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Old 23rd March 2013, 02:00 AM   #2278
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Originally Posted by obiwankenobi View Post
Dear friends, here is a first revision of my GM3 schematic.
Thank you oiphy, please check if Vitali's appreciated advice is well reflected here.
Protection circuit transistors are named Q1, Q2, etc. Protection components are numbered 101, 102, 103 ... etc because the original circuits overlapped numbering, so amplifier and protection components got confused.
Amplifier transistors are T1, T2, etc. and I tried to copy the same distribution as in GM 9.2 so we can understand all comments about GM 9.2 applied to GM 3.
Please feel free to catch any of my errors and report.

Thank you very much.

Roberto Berner
thanks for your good job
i like creat one
can i use this amp in my car?
is it stable for 2 ohm empedanse?
do you have pcb for that?
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Old 23rd March 2013, 05:22 PM   #2279
oiphy is offline oiphy  Norway
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@Hadighorbani

Nagys Audio - Products - Provider of High End Audio Interconnect Cables
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Old 23rd March 2013, 08:30 PM   #2280
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Originally Posted by oiphy View Post
thanks friend
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