Subject: Re: Class B amplifiers: what are the large low-value resistors for?
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Date: Thu, 14 Nov 2002 07:05:22 GMT
NNTP-Posting-Date: Thu, 14 Nov 2002 08:05:22 MET
"Paul Burridge" schrieb im Newsbeitrag
> 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...
quod anno Domini millesimo quatercentesimo octuagesimo secundo...
Do you want to demonstrate your ability reading Latin or is it just copied?
This was written 1500 yrs. before, now give a guess:
Aurea prima sata est aetas, quae vindice nullo,
sponte sua, sine lege fidem rectumque colebat.
poena metusque aberant, nec verba minantia fixo
aere legebantur, nec supplex turba timebat
iudicis ora sui, sed erant sine vindice tuti.
The emitter resistors are needed to stabilize the bias current and/or if you
parallel a couple of output transistors, to achieve a higher current drive
capability. You can take higher values, but have to recalculate well the
required power handling capability and you will loose this power on the
loudspeaker. You might also have to modify the bias current adjustment.
BTW the values are easily available in any shop.
electronic hardware designer