[Boatanchors] Carbon Mic Rejuvenation (& related)

[mac]

Bill is correct about passive elements and power gain.  Perhaps some  
of the confusion here centers around consideration of a carbon  
microphone as a "passive element."  Standing alone it certainly is,  
just as a vacuum tube with no filament or B+ applied would be  
passive.  Put the tube in a practical circuit though, i.e., power  
source and a load impedance and it becomes the "active " element we  
usually consider it to be.  So, would a carbon mic augmented with a  
load impedance and bias (power) supply now (properly) be considered an  
"active" element?  Different from a crystal or dynamic mic neither of  
which require a bias (power) source to operate.  Academic question but  
interesting.....

Dennis D.  W7QHO
Glendale, CA

*******************
On Mar 16, 2013, at 10:51 AM, Bill Carns wrote:

> 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
>
> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net
> [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Bill Carns
> Sent: Saturday, March 16, 2013 12:44 PM
> To: 'rbethman'; boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] Carbon Mic Rejuvination
>
> As a newcomer to the list, I hate to be argumentative, but no passive
> element has Power Gain..  By definition, Power Gain is some  
> expression of
> Power Out divided by Power in where this number must be more than  
> one, or
> the db expression of same.
>
> As a physicist, and electrical engineer, I can tell you that no  
> passive
> element has gain, because the laws of physics would be violated.
>
> We all know that Pin = Pout in a line transformer for instance.  
> (Less of
> course any small losses)... But Pout cannot be more than Pin.
>
> 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 gain.
>
> Sorry....just could not let that misunderstanding and misstatement  
> pass
> without comment.  Perhaps you are confusing "Force" for power...   
> They are
> not the same.
>
>
>
> Bill
>
>
>
> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net
> [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of rbethman
> Sent: Saturday, March 16, 2013 12:23 PM
> To: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] Carbon Mic Rejuvination
>
> Someone would have to demonstrate the "power gain" or modulation of  
> a gate
> valve.
>
> Bob - N0DGN
>
>
> On 3/16/2013 12:58 PM, J. Forster wrote:
>> Richard,
>>
>> More correctly, carbon mikes are 'energy modulators'- they modulate
>> the flow of electrical energy in response to a mechanical input...
>> very like a valve for water.
>>
>> They DO have power gain, as do valves for water or air.
>>
>> Best,
>>
>> -John
>>
>
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