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Old 18th April 2007, 06:42 PM   #901
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Default At left you can see temperature in centigrades, at your rigth the current in one

of the amplifier rails...the ampere meter was in series.

regards,

Carlos
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Old 18th April 2007, 06:44 PM   #902
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Default The voltage amplifier transistor was checked during those hard testings

The temperature was near the 38 degrees centigrades.

regards,

Carlos
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Old 18th April 2007, 06:47 PM   #903
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Default Sabotage was tried...the soldering iron tip touching the transistor top.


Heat was transfered from the screw to the transistor top, to the heatsink... and them to the junction...after 2 minutes a good ammount of stand by current was reduced.

The VBE multipler had acelerated his speed to control temperature increase.

regards,

Carlos
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Old 18th April 2007, 06:50 PM   #904
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Default Those hard tests started with bias adjusted to 50 miliamps...amplifier cold.

After testing with overdriven.... the current gone to 72 miliamps.

And the temperature never gone over 41 degrees celsius..this is a good human fever..not too hot for a power amplifier.

regards,

Carlos
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Old 18th April 2007, 06:51 PM   #905
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Default Here is the final vision..by the third time, the amplifier received my aproval

It is stable.

regards,

Carlos
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Old 18th April 2007, 06:53 PM   #906
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Default Modifications will be shown in those next two images.


Simple modifications..... a single resistance...the inclusion of the VBE multiplier that was tested with Bittner suggested values, and a new stand by current...more cold amplifier during stand by.. driver transistors works more cold now.

regards,

Carlos
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Old 18th April 2007, 06:58 PM   #907
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Default Here is the modifications part 2.

attached,

Carlos
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Old 18th April 2007, 07:04 PM   #908
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Default Nordic, my dear Nephew..you do not need to buy nothing...search for 2 resistances

with values that goes from 10 ohms to 150 ohms...no problem..they can be different...better if they are the same...less confusion.

Install those resistances in series with your rail wires..cut them and them install the resistances extremes into those two point you have now...as you have cutted the positive wire, for instance...... then, install a DC voltimeter....10 to 50 Volts DC may work

Voltimeter probe points will be: one at the resistance rigth side and other at the resistance left side...reading the voltage developed when the electrons cross that resistance...and applying ohms law..you will have your current reading

Do the same in the negative rails...with the other resistance...install a second meter there.

The voltage you obtain.... enter into a calculator machine.... expressed in volts..and them divide by your resistance expressed in ohms...the result will be the current entering...ohms law application only.

Fuse are other things...wire to give a guaranteed low resistance fuse is in the board...this is external related the board...not neede to install those things in the fuse place...unless you prefer this way.

regards,

Carlos

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Old 18th April 2007, 07:32 PM   #909
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Could you post the full schematic includeing the VBE muliplier?

It will help me understand better, but I want to try the original version first if it is ok.... You said I should aim for 50mA bias in the rail, is that for the positive rail?
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Old 18th April 2007, 07:36 PM   #910
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Default Yes..for the positive rail you can adjust 50 miliamperes.

The modified schematic will be posted in the Greg home page soon.

Also i will make something not so pretty to send you....send my your mail please.... i will make attachment for you..as the standard schematic use resistances...diodes and VBE multiplier are evolutions to the ones do not want to use big heatsinks and fan blowers.

panzertoo@yahoo.com


regards,

Carlos
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