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Subject: Re: Class B amplifiers: what are the large low-value resistors for?
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Thu, 14 Nov 2002 06:34:13 GMT
NNTP-Posting-Date: Wed, 13 Nov 2002 22:34:13 PST
Organization: EarthLink Inc. -- http://www.EarthLink.net
The emitter resistors are there to:
1) Allow sensing of output-stage current
2) Provide some temperature stability for output-stage bias levels (in the
case of class A or AB
If you increase the value of these you will increase the open-loop output
impedance of your amplifier. Not good for performance into reactive loads.
You'll also lose more power from them.
"Paul Burridge" wrote in message
> The circuits I've seen for class b amps mostly seem to have two 0.25
> - 0.33 ohm resistors between the emitters of the output transistors
> concerned. Are they really necessary at all? And if I don't have these
> ultra-low values to hand, can I get away with 1ohm ones and what would
> be the effect on performance?
> Noverint universi per presentes et futuri...
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