Ah... so the "plot sickens..." ;-)
Thanks for that further gloss. I gotta learn more about diodes.
A local Elmer told me to make a voltage divider (like an L-pad
attenuator) if I wanted to assure a predicted voltage drop, whereas
using one resistor was not as predictable. This parallels what you are
saying here. This is why I used an L-pad attenuator in my microphone
matching circuit, but also explains why I used a single resistor in
knocking down the bias voltage - I was not as concerned about the
accuracy of the result on that aspect, where I was on the mic attenuator
bit. Now I will have to learn about how diodes might be used... new
horizons for me.
----------------- JHR ------------------------
On 3/7/2014 8:51 AM, Bob McGraw - K4TAX wrote:
Typically a silicon diode has about 0.7 volt drop per unit. Thus two
diodes in series would drop 1.4V and three in series would drop 2.1
volts etc. The advantage of using a diode over using a R has to do with
constant voltage drop using a diode where a fixed R will have different
voltage drop values depending on current demands. Some fans may have a
higher starting current than running current. With a critical value of
R one could experience a condition where the fan won't start due to the
IR drop. This problem won't exist with a diode string when used as a
voltage dropping method.
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