
February 7th 08, 10:08 PM
posted to rec.audio.opinion,rec.audio.tubes,uk.rec.audio
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Bipolar Transistors for Audio
"David Looser" wrote in message
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"robert casey" wrote in message
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But back in the early 70's, table radios made the transision from the
"All American 5ive" tube circuit to a solid state circuit that used a
high voltage bipolar transistor and output transformer for the audio
output.
I'm not sure exactly when this transition was made, but I do know that
it occurred sometime well before the "early 70's", I would say that the
transition occurred in the mid 60's, I know from personal experience
that these radios were already in production by late 66, when they first
went into production I don't know.
I was thinking of the SS radios that were "hot chassis". The audio
output transistor had about 100V B+ on it. Before these, there were some
SS radios that had small power transformers and were essentially portable
circuits inserted inside a table radio cabinet. But it's the hot chassis
high voltage transistors that ran in class A "single ended" I was
thinking of.
That's probably why we never saw them here in the UK. There were the
occasional single-ended transistor output stages in early SS and hybrid
car radios, and some Japanese-made TV sets, but that was about it. A 300V
B+ supply would have been rather too much.
I thought the common bipolar transistor was a "triode". 
It's a three-electrode device, so yes, it's a triode. That doesn't mean
it's characteristics are similar to those of a thermionic triode though.
My Chinese friends tell me that the word "transistor" translates into
"crystal triode" in Chinese. :-)
Err..., "transistor" is a contraction of "transfer-resistor", but what it
*is*, is a crystal triode. So if any language group wants it's own word
for the device, rather than just adopt "transistor", then using their own
words for "crystal triode" makes a good deal of sense.
David.
Somewhere around at home, I have an extremely old transistor that is marked
as "Crystal Triode". It is so old that it has a hand written serial number
on it
Keith
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