I would, in the future, tend to shy away from
the classification of an 'amplifier' stage as
Class A, B or C unless that stage were truly
working as an amplifier with specific bias set
up so as to actually attain a particular bias
and hence operate as a Class A, B or C stage - this
is as opposed to a single device operated as a
simple on/off switch in some sort of pulse width
modulation mode.

As to where RF begins - that's easy. Does it involve
'radio frequencies' and the technologies classically
employed to modulate, amplify, detect, filter,
demodulate or radiate EM energy as opposed to 'audio
frequencies' which have in past decades normally
'modulated' an RF carrier in order to transmit
intelligence though the ether from point A to point
B?

I'm afraid today's 'digi-head' has blurred all
distinction between the two ...

Jim

----- Original Message -----
From: "David VanHorn" <dvanhorn@CEDAR.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, February 11, 2002 11:25 AM
Subject: Re: [pic]: Can you amplify with a single 2n2222 ??


> At 08:41 AM 2/11/02 -0600, Jim wrote:
> >    "Alternatively, you can use the transistor as an
> >     open collector driver, which is a class-C amplifier."
> >
> >I don't get it.
> >
> >Maybe I'm from the old school where Class C amps
> >were only used for RF
>
> Where does RF start, exactly?
> Connect an antenna to it.
>
> >(I can't recall a single audio
> >application for a stage biased Class C and conduction
> >angle for each cycle was significantly less than
> >180 degrees) where the tank circuit provides for the
> >balance of the re-creation of the waveform (tank, or
> >LC resonant circuits being analogous to balance wheels
> >or tuning forks of sorts).
>
> Probably because they were worried about fidelity.
> If you're driving a beeper, fidelity is right out the window.
> You can drive a beeper as part of a resonant circuit, with the beeper
> acting as a lossy tank capacitor.
>
> >The "open coll." app above sounds more like the 2n2222 is
> >being used as a switch, perhaps in PWM mode as in
> >class D or the like.
>
> You could do that too.
>
>

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads