I'm building Shaan's PeeCeeBee v4h and I need to match hfe on some bc546 and bc556.
His design calls for B gains.
I have 100 bc546C and 10 bc556B
The gains don't match. Anyone interested in mail trading some of your bc546B for some of my bc546C?
I've got stamps, envelopes, and lots of anti static bags...
His design calls for B gains.
I have 100 bc546C and 10 bc556B
The gains don't match. Anyone interested in mail trading some of your bc546B for some of my bc546C?
I've got stamps, envelopes, and lots of anti static bags...
The Hfe you require is a minimum. BC546C has a greater Hfe and will suit well.
Match a few of those.
The gain is set by component values, not the Hfe of the semiconductors.
If you had BC546A and needed BC546B, there would be good reason to want to get better semiconductors. If the overall gain of the stage is say; 60 and you fit semiconductors suitable for up to 140, that is fine. Not the other way around.
Match a few of those.
The gain is set by component values, not the Hfe of the semiconductors.
If you had BC546A and needed BC546B, there would be good reason to want to get better semiconductors. If the overall gain of the stage is say; 60 and you fit semiconductors suitable for up to 140, that is fine. Not the other way around.
Can you post schematic here?
Would like to check whether actual Hfe matching is needed or not for better suggestions.
Point being that the "letter" spec is a very broad one, a lower gain C can be actually very close to a higher gain B.
Besides, "10 BC556" means a couple bucks total,
2 envelopes and shipping both ways is way more expensive than just ordering the proper ones.
Can't imagine anybody trading $2 worth of easy to get transistors.
FWIW I always order 100 each just to stock in the parts bin, always useful.
Guess many do the same.
Also, designs depending much on a particular transistor gain to work are not too good to begin with; "good Engineering" is to make designs robust and as much "parts independent" as possible.
EDIT:
just checked and found THIS;
As you can see, Hfe is absolutely NON critical.
Any 2N5401/5551 Hfe is way lower than any BC5xx... the price paid for higher Vce ... And yet...
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Thanks for the replies. It's just the input pair which is recommended for matching, and maybe I can find a closer match.
I picked a couple from each and found the gain was about 300 for the B and 600 for the C.
Figure 50 cents for a stamp to send some picket change is better than spending $4 on ebay for Chinese parts or $8 shipping with mouser.
If no one is interested, that's okay too.
I picked a couple from each and found the gain was about 300 for the B and 600 for the C.
Figure 50 cents for a stamp to send some picket change is better than spending $4 on ebay for Chinese parts or $8 shipping with mouser.
If no one is interested, that's okay too.
As requested, the schematic from
https://www.diyaudio.com/community/threads/peeceebee-v4h-gb.317151/