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Modify Hood Class A Amp for DC Path and Unipolar Output

epsolutions

Sep 7, 2019
116
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Sep 7, 2019
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116
I have two Hood 1969 class A amplifier boards at hand. I would like to modify the signal path to DC coupled. The signal source is PC sound card line out (nom. 2Vpp).

That is a bipolar signal so I need to adjust the DC input level to make the amp output unipolar. The purpose for this is to drive a large air coil (22R) in such a way that the coil's field remains unipolar, i.e. does not reverse. The purpose is magnetics experiments in the 20Hz-10KHz range. The amps would run on 12VDC.

hood.png
Orignal Hood circuit is here. Please see my proposed mod below. I prefer to use these amps, and not scratch build, because they are already in my bin with large heatsinks attached. Corrections or suggestions would be very much appreciated.
hood-input-adj.png
 
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