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

[gary]

Gotcha. LEDs are hetero junction, yielding more than a diode drop.


On 3/25/2012 5:05 PM, David wrote:
> 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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