[time-nuts] Distribution amp - Use a video amp unit ?

David davidwhess at gmail.com
Mon Mar 26 00:05:02 UTC 2012


On Sun, 25 Mar 2012 16:39:57 -0700, gary <lists at lazygranch.com> wrote:

>I'm not so sure about the circuit. The base drive on Q3 is more of less 
>AC given that the resistor can only pull current out of the base. That 
>is, I don't see a DC bias on Q3.

R7, R8, and LED D2 sets the base voltage at about 1.8 volts through
R4.  Subtract Vbe and Q3's idle current will be about 36 milliamps set
by 1.2 volts across the 33 ohm emitter resistor.




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