Are these ok for usage in a vas / current source ?

[chriscam]

I'm looking at using a complementary pair of these transistors in a classic vas with currentsource setup. The original uses bd139/140 pair. The specs look ok to me ....

 

[AndrewT]

100Vce0, 1A, 550mW, >150 hFE, 7.5pF Cob@10Vcb, >100MHz @ 50mA !!!!! and preponderance of sat data.

The hFE holds up very well at low currents, but all else seems to point to switching duty,
where efficiency of power transfer over rules everything.
It may turn out to be very suitable if the Cob can be tolerated.

For VAS duty, I would look for higher hFE, lower Cob, lower current rating (100mA to 200mA) in exchange for a higher fT and higher Vce0.

 

[chriscam]

Ok, thanks !

 

[nigelwright7557]

I'm looking at using a complementary pair of these transistors in a classic vas with currentsource setup. The original uses bd139/140 pair. The specs look ok to me ....

B139/140 have been used many times in designs for VAS and current source.

 

[jcx]

A community dedicated to helping everyone learn the art of audio. Projects by fanatics, for fanatics! - Search Results for vas transistor

http://www.diyaudio.com/forums/gtse...k&cof=FORID:10&ie=UTF-8&q=bd139+vas&sa=Search

 

[CBS240]

Driver transistor, perhaps. VAS, not so good.

 

[chriscam]

I did search using the search forums option which obviously doesn't work as well as the google option. Hmm, anyway, I found a whole bunch of usefull info, reading...

Thanks for pointing !