epsolutions
- Sep 7, 2019
- 97
- Joined
- Sep 7, 2019
- Messages
- 97
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.

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.

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.

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.
