[ARC5] Carbon cartridge replacement circuit

[Brian]

Well Richard,
I would have to say, once again, that you have an interesting slant on 
electronics theory. From which electronics degree college did you graduate?
What Class of amplifier do you think it is? A, B, C, D, G, H ???
Actually, there is no power output from a carbon microphone, except in terms 
of self-heating. All the power comes from the power supply delivering 
varying current in response to the mic element's changing resistance. Yes, 
there is power going into the mic transformer's primary; but once again, 
that comes from the power supply, not the mic element.
There is no similarity to a vacuum tube, because there is no grid to control 
current flow - in fact there is control at all, except in the shape of the 
flares and wind buffering / filtering around the mic element, altering its 
frequency and 3D response pattern. It is the drive that is all mechanical, 
not the control. The nearest you could define it as is a transducer, 
converting mechanical energy into changes in resistance.
By your definition, you would have to claim that a water tap was an 
amplifier - the mechanical action of operating its valve varies a powerful 
stream of water. I wonder if this is a Class A, B, C, D ... amplifier? Maybe 
a hydro-electric generator is an amplifier, turning the potential energy of 
the head of water into the dynamic energy of electrical power?
Wow, your last sentence that I have left here beggars belief - output power 
of a valve is the variation in plate resistance?? So, P = delta R? Hmmm.
73 de Brian, VK2GCE.

On Friday, April 28, 2017 11:28 AM, Richard Knoppow said:

     A carbon microphone is an amplifier because the power out is
greater than the power in. The controlling force is the acoustic energy
available to the diaphragm, the diaphragm in turn converts the acoustic
energy to mechanical energy which moves one of the contacts with the
resistance element. This in turn varies the voltage across the resistive
element and varies the current applied to it. The input energy, as
absorbed from the air, is a small fraction of a watt but the output can
be very large depending on the dissipation of the carbon element.  The
action is rather like a vacuum tube which also acts as a variable
resistor. The input power to the grid is very small compared to the
output power from the plate the variation being in the effective plate
resistance.
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