Is high, or low, Hfe better for a CCS? - Page 4 - diyAudio
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Old 15th October 2012, 09:34 PM   #31
jcx is offline jcx  United States
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Default topology trumps

still would add another Q before worrying about which Q parameters are "best"


note the factor of 100x in front of the 3 Q yellow waveform plot
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Old 15th October 2012, 10:11 PM   #32
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Now wheres the fun in that?
Well okay but its a different kind of fun.

Thanks
-Antonio
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Old 11th October 2014, 08:53 PM   #33
pwan is offline pwan  United Kingdom
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Sorry for bringing this old thread up again.

With my limited knowledge, not sure whether or my understanding is correct. So .... For CCS transistor (8-10ma idle current), the lower hfe the better ?

Thanks in advance for clarification.
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Old 11th October 2014, 09:13 PM   #34
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by pwan View Post
Sorry for bringing this old thread up again.

With my limited knowledge, not sure whether or my understanding is correct. So .... For CCS transistor (8-10ma idle current), the lower hfe the better ?
Things are never simple and clear-cut: if you talk about a robustly dimensioned CCS, lower Hfe is in principle better, but in shady areas anything can happen
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Old 11th October 2014, 09:26 PM   #35
pwan is offline pwan  United Kingdom
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Quote:
Originally Posted by Elvee View Post
Things are never simple and clear-cut: if you talk about a robustly dimensioned CCS, lower Hfe is in principle better, but in shady areas anything can happen
Thank you Elvee.

That should be a good news. In my case, I mean the CCS for VAS stage ( 10ma with BC546C as controlling resistor). The VAS is PNP. Its complementary (NPN) for CCS comes in much lower hfe grade. To get the NPN ones with the same hfe grade as PNP is x10 times more expensive.
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