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Elektor PA300

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PA_300/400

For the C9 capacity it is the compensation, at least we say so in French. Be careful, she plays on the slew-rate. Everything is indicated on the AOP 55.xxx datasheet. Normally it's more like 22 pF. The more the capacity decreases, the more the slew-rate increases. From memory it is 13v / µs maximum. Why Elektor put 33 pF, mystery. But it works. Mandatory to connect a 33 pF on pins N ° 6 & N ° 2, otherwise guaranteed oscillations.
Protection is not a problem, at least not on our side. Attention, it is preferable to mount the power supply as the original diagram. If unable to correct, the NE55.xxx is a copy. Take a circuit of big brand and not of Chinese origin !!!!.
We installed a Pa version 400, apart from a Pcb error corrected by bridging, it works well. The routing of our version took time, the Pcb is not yet fixed.
We are also testing a version with 78 / 79.xx regulators. Better in terms of stability and noise. Advice from an engineer who is a size in France.
Greetings, Jacky
 
PA_300/400/600

Herewith Pa. 600
Greetings
 

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PA_300/400

Hi, Kay.
It should be understood that two L-shaped angles of 40x40_Ep = 5 mm is less expensive than a U of 80x40.
It is easier to machine the angle iron than the U. In addition, it is not too standardized, among manufacturers. But you can do it at a factory.
Then the, L must be connected to the main heatsink. Or do a tunnel assembly. 8 pairs at 100 volts this starts to make a nice heater. Then it is a question of feeling and of handyman ability. We are fine with the approach used on the top view of the amplifier that I have detailed. And if assembly in bridge then, it is obligatory tunnel. I hope to have answered.
Greetings.
Jacky
 

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Don´t think transistor per transistor but the big overheated block you are trying to cool.

As in: 1 or 2 (depending on layout) large "tunnels" where you concentrate large airflow and lots of fins together.

A CPU is on its own, or maybe you have two in a PC case, not 8/12/16/whatever transistors all together side by side.

And total heat generated is more than anything a CPU can generate.
 
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