BC550B/C (npn) and BC560B/C (pnp) are the European generic low-noise / high-beta transistors. They must have been made since the late '70s or so? You can get transistors with higher Vceo for this level of Cob and beta nowadays, and their Rbb' still is above 100 ohms, but still when you need a cheap small-fry transistor that'll keep its beta well at small Ic and doesn't need to sustain any outlandish voltages, these aren't a bad bet.
Surface mount versions are called BC850 and BC860, respectively.
Surface mount versions are called BC850 and BC860, respectively.
From looking at the data sheets, the Hfe goes up as you go from the A, B, or C versions.
Jerluwoo shows the "A" version for the BC560 and "B" version for the BC550.
Will substituting the "C" version, which seems easier to find in the TO-92 style, still work in the above circuit or does one have to use the "B" versions for the 550 and "A" version for the 560?
Thanks...
Jerluwoo shows the "A" version for the BC560 and "B" version for the BC550.
Will substituting the "C" version, which seems easier to find in the TO-92 style, still work in the above circuit or does one have to use the "B" versions for the 550 and "A" version for the 560?
Thanks...
Sorry have not been checking in this past week. Both the 550/560 are the 45V 100mA parts both in the 300-400 hfe range, just for some reason the models were named as such when I added them and didn't really think to change them. I tried a few different complimentary types, 2n3904/6 2n4401/3 ss9014/15, all with very close results with the 550/60 giving slightly better numbers. Probably all down to available beta at low current, since this circuit uses feedback to correct hfe based on output current.
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