ORIGINAL MESSAGE:
On Mon, 3 Sep 2012 11:15:20 -0600, you wrote:
>
>Bill,
>I'm not sure what you mean by a zener diode "supplying negative current." A
>zener diode doesn't supply any current at all, positive or negative. It
>sinks current while maintaining a constant voltage. If, for example, 100mA
>is supplied by the "feed resistor" and there is -20mA of negative screen
>current, the the zener will sink 120 mA. If there is +20mA of positive
>screen current, the zener will sink 80mA. If the screen current rises to
>+100mA, then the zener will drop out of regulation and the screen voltage
>will drop. That said, I agree that no separate bleeder is required with a
>zener diode regulator. In effect, the zener acts as the bleeder.
>73,
>Jiim W8ZR
REPLY:
I think we agree on everything but semantics. I often get tangled up with the
"current flows from positive to negative" boys over the terms source and sink.
Benjamin Franklin got it wrong and the IEEE and others have been perpetuating
the error ever since. I usually ask the positive to negative boys why a tube has
to have a heated filament or cathode in order to "receive" current flow from the
anode. Still waiting for an answer.
73, Bill W6WRT
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