They cost 3.11 Euro in single quantity. Hardly very expensive.
Funny that they seem available but the datasheets not.
http://www.profusionplc.com/scripts/wsisa.dll/pcatlst?ipartno=all&imanuf=sanken&itypes=all
Funny that they seem available but the datasheets not.
http://www.profusionplc.com/scripts/wsisa.dll/pcatlst?ipartno=all&imanuf=sanken&itypes=all
It's very easy to temperature compensate a complementary set of Power MOSFET's like IRFP240 / IRFP9240.
You can either use:
1..A small MOSFET like IRFP614I with 2 resistors and a trimmer on the gates, much like a normal BIAS transistor in a bipolar output stage, or :
2..exploit the fact that the derating factor of an IRFP is roughly the same as a normal Vbe (2,2 mV / K). Use a constant voltage source, and a Vbe doubler with a bipolar transistor (2N2222 or BC548) and you'll be all set!
These devices are great fun to build with, but their Rs varies a great deal with load, so you must find a way to compensate for that in your amplifier circuit. (if you want good sound - preferably without feedback loops).
You can either use:
1..A small MOSFET like IRFP614I with 2 resistors and a trimmer on the gates, much like a normal BIAS transistor in a bipolar output stage, or :
2..exploit the fact that the derating factor of an IRFP is roughly the same as a normal Vbe (2,2 mV / K). Use a constant voltage source, and a Vbe doubler with a bipolar transistor (2N2222 or BC548) and you'll be all set!
These devices are great fun to build with, but their Rs varies a great deal with load, so you must find a way to compensate for that in your amplifier circuit. (if you want good sound - preferably without feedback loops).
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