[Boatanchors] Carbon Mic Rejuvination

[jmfranke]

Sorry I omitted the fact that the microphone amplifier does need a power 
supply. I do agree 100% with your comments.

John WA4WDL

--------------------------------------------------
From: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
Sent: Saturday, March 16, 2013 4:34 PM
To: "Bill Carns" <wcarns at austin.rr.com>; "'rbethman'" 
<rbethman at comcast.net>; <boatanchors at mailman.qth.net>
Subject: Re: [Boatanchors] Carbon Mic Rejuvination

>
> ----- Original Message ----- 
> From: "Bill Carns" <wcarns at austin.rr.com>
> To: "'rbethman'" <rbethman at comcast.net>; <boatanchors at mailman.qth.net>
> Sent: Saturday, March 16, 2013 10:51 AM
> Subject: Re: [Boatanchors] Carbon Mic Rejuvination
>
>
>> That last paragraph should have read:
>>
>> There has to be "Conservation of energy" in any system ....which 
>> basically
>> says there is no free lunch.  If you do not apply external power - like 
>> in a
>> supply to an amplifier, then a passive element like a water valve, or a
>> passive modulator like a carbon mic, cannot have POWER gain.
>>
>> You can have voltage gain....like a transformer....  But no power gain. 
>> If
>> you gain voltage, you lose current.
>>
>> Bill
>
>    The carbon microphone DOES have a source of external power.  There 
> _must_ be a source of DC. It can be a battery or the cathode current of a 
> vacuum tube. In any case there is a power gain. One of the pre-vacuum tube 
> attempts at telephone repeaters was the use of a carbon microphone driven 
> by a magnetic receiver.  These did not work very well due to the high 
> noise but did work.
>    Now, while a valve controlling the flow of water or gas is not 
> electronic it also has a source of external power. That can be someone's 
> hand or an electrical or hydraulic actuator of some sort. In any case the 
> amount of energy needed to move the valve is a fraction of the energy it 
> may be controlling.  Again, its a form of amplifier.  A carbon microphone 
> is, in fact, a form of valve, as is a vacuum tube, controlling an external 
> source of power which can be substantially larger than the power applied 
> in actuating it. One can use a potentiometer as an analogue, it is a 
> variable resistor which is varied by a small mechanical force.  The 
> electrical force carried by it can be a fraction of the force needed to 
> change its value, again its an amplifier. No laws of nature are being 
> violated.
>
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>
>
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