Supertex makes depletion FETs in TO 92 case styles up to 500V
http://www.supertex.com/products/selector_guides/102
I have run the A40 board up to as high as ±95V with six pair of MJ15024/25 driven by one pair of 2SA1302/2SC3281 for 600W at 4R (class AB).
http://www.supertex.com/products/selector_guides/102
I have run the A40 board up to as high as ±95V with six pair of MJ15024/25 driven by one pair of 2SA1302/2SC3281 for 600W at 4R (class AB).
One Up And Cooking
Its been a while but, I have one channel up and cooking. I have had to turn the bias down as the heat sink gets up to 140F pretty quickly. Based on the original article where "The One And Only" speced .68 ohm emitter resistors and a reading of approx 1 volt between R16-18 some basic math says that each device has about .75 amperes of current flowing through it. I used .47 ohm and once I get more than about 250mv across each emitter resistor the heat sink temps soar.
Its been a while but, I have one channel up and cooking. I have had to turn the bias down as the heat sink gets up to 140F pretty quickly. Based on the original article where "The One And Only" speced .68 ohm emitter resistors and a reading of approx 1 volt between R16-18 some basic math says that each device has about .75 amperes of current flowing through it. I used .47 ohm and once I get more than about 250mv across each emitter resistor the heat sink temps soar.
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Hot Coffee ....
It has taken a few years to figure out how to keep my coffee hot while working on various projects in the basement. A freiend accross the street helped out with the heatsink configuration. He has access to a computer controlled milling system. He removed one of the fins and that let us drill holes to mount the devices. Now i just have to finish the other side.
It has taken a few years to figure out how to keep my coffee hot while working on various projects in the basement. A freiend accross the street helped out with the heatsink configuration. He has access to a computer controlled milling system. He removed one of the fins and that let us drill holes to mount the devices. Now i just have to finish the other side.
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