[ARC5] Carbon cartridge replacement circuit

[Tom Lee]

Minor nit: A carbon mic is class A. The current never goes to zero; the 
mic is always conducting.

--Cheers,
Tom

-- 
Prof. Thomas H. Lee
Allen Bldg., CIS-205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu
650-725-3383 (public fax; no confidential information, please)

On 4/28/2017 9:20 AM, WA5CAB--- via ARC5 wrote:
> Brian,
>
> Although it smacks somewhat of angels and pin heads, I would have to 
> agree with Richard.  If you connect a reasonably efficient transducer 
> that converts the varying current back to sound, the sound should be 
> as loud or a little louder than the sound that produced the varying 
> current.  Which very definitely is not true of any other type of 
> microphone.
>
> And to answer your other question, it would be a Class B.
>
> Also, NO amplifier produces more power out than power in. That would 
> require an efficiency greater than 100%.
>
> In a message dated 04/28/2017 07:41:52 AM Central Daylight Time, 
> brianclarke01 at optusnet.com.au writes:
>> 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.
>> <snip>
>
>
> Robert & Susan Downs - Houston
> wa5cab dot com (Web Store)
> MVPA 9480
>
>
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