Can anyone say who makes the bc547 bk033 npn transistor?

[kimelopidaer]

Hi everyone.
Numerous places sell bc547 transistors but I'd like to find the particular npn component that is also stamped with bk033. This little guy just works for me, is all.

Perhaps someone knows what those letters/numbers indicate. I'd appreciate any info, such as manufacturer, a link to a data sheet (been searching) etc.



Regards,
K

[DiscoVlad]

a manufacturer specific production code?

possibly plant, and date e.g.:
BK = some factory in Bangkok, 033 = week 33 of 2010?
the point I'm making is that it could be anything. Why won't any other BC547 do? Their characteristics aren't terribly variable.

[kimelopidaer]

I see...so it's could just be manufacturing info.
Last year I purchased alot of variety packages from futurelec for experimenting with different circuits. These bc547's stamped additionally with bk033 were amongst the many different transistors that arrived. 
when I put a circuit together that inspired me to build another for my friend, I ordered bc547b transistors from small bear.
They are from a different manufacturer, labelled c547b and stamped ph71.

I put them into place on the breadboard but they just don't have the same properties. No audio signal actually passes through them; the bc547's actually control an oscillator that turns on a photocell (its a type of trem)

I figure the gain characteristics must be slightly different between manufacturers...is that a reasonable assumption?
Can one order just plain bc547 transistors, or are they all marked a, b, or c?

Appreciate anyone's input on that.
Thankyou,
K

[artifus]

check pin outs and/or adjust surrounding resistor values. use pots or trimmers perhaps.

[StereoKills]

They are from a different manufacturer, labelled c547b and stamped ph71.
I put them into place on the breadboard but they just don't have the same properties. No audio signal actually passes through them.

Different manufacturers may have different pinouts - check the datasheets.

Can one order just plain bc547 transistors, or are they all marked a, b, or c?

Search Mouser for BC547 - You will get 4 pages of results in various flavors. Many are obsolete at this point, but there was at least 1.5-2 pages of stocked versions. First on the list is a vanilla BC547.

[kimelopidaer]

Yes, while I am prepared to do that if absolutely necessary, I am reluctant since I used three trimmers in the oscillator to achieve a "balance" of sorts between a number of sound variables that were important to me. In other words, I'm initially daunted by the idea.

Currently waiting for a reply from futurlec. Will search Mouser's catalogue now. Thanks for tip Stereokills.


K

[artifus]

there are other more knowledgeable transistor heads around here who will hopefully chip in to help you out, but in my limited understanding if the transistor isn't doing it's thing you may need to adjust emitter and/or collector resistor(s) to get it to do so. transistors can vary a lot, even those with the same names, numbers or from the same batch.

any npn should do really.

edit?

[kimelopidaer]

I'm not really sure what those numbers and letters refer to now.

Printed on the flat side of a t0-92 package transistor:

Bc547
Bk033

Does the b in bk033 indicate that this is a bc547b transistor?

I've seen the b on the first line with some other makers components.
Dear dear...

[StereoKills]

The BK033 is almost certainly the plant/batch code. If it was the B version it would be in the part number. Typically you'll look for the manufacturer's logo to figure out the maker.

[Mike Burgundy]

Have you verified pinout and compared HFE? I've seen CEB, CBE, there might be others. Depending on ciruit different HFE might also cause different behaviour. BC547 (without a gian designator so the full possible range) has an HFE range of 100-800. That's a pretty large spread. That should solve your problems.

[kimelopidaer]

Update: a kind reply from futurlec has emailed me with the facts.

The transistor in question is indeed a standard bc547.
Bk033 refers to the batch code.

Discovlad and stereokills, you had it.
There was actually no manufacturers logo on the casing. Futurlec said they would not be able to obtain more transistors stamped with bk033, which of course is certainly understandable given that this was a specific batch and who knows where that quantity ended up.
They can send functionally identical components though.

Mikeburgundy, I checked the hfe for bc547b (min200 max450) so thanks...could explain it.



Thanks to everyone for their input. For the last three days I have been obsessed with little numbers written on a piece of plastic but I feel alive.

K

[StereoKills]

BC547 (without a gian designator so the full possible range) has an HFE range of 100-800.

No wonder you can't find one that sounds the same in the circuit. Your best bet is to measure the hfe of the trasistor you like and then you'll be able to find a similar one!

Here's a detailed transistor testing circuit:
http://sound.westhost.com/project31.htm

[kimelopidaer]

Appreciate that. I was actually looking around the day earlier for this type of thing. I found the treatise at Geofex that discusses germanium transistor gain checking. This one you link to appears to go deep.
K

[DiscoVlad]

Here's a detailed transistor testing circuit:
http://sound.westhost.com/project31.htm

This can probably be cut down quite easily for testing small signal devices, you wouldn't need the HV parts for instance.
For what it's worth the numbers in the data sheet seem to show that the devices without the ABC suffix either aren't gain sorted... or could fit into the A and B groups, so these would have more variation.
eg. http://docs-asia.electrocomponents.com/webdocs/0b21/0900766b80b21857.pdf

[zombiwoof]

My understanding is that silicon transistors don't generally have the leakage problems like germanium does, I would just measure them with a meter that has an hfe function, to find comparable substitutes.  The GEO transistor tester (Small Bear also has a simplified version of it in an article on his site) is really for testing germaniums, to figure the leakage and true gain figures.

Al

[Mike Burgundy]

Zombiwoof's correct - if you have a DM with HFE test use that (it's a great tool to have, if you don't already have one you might want to consider it). The leakage of germaniums screws with the readings, that's what the GEO tester is specifically for. It will work with Si just fine, but a DMM is easier.

[boog]

fwiw, one of my black russian muffs has bc547s. of course that's the one that's not here so i can't tell if it's the kind your looking for. and i'm not really sure if this info is helpful; but maybe it at least it might narrow the production date range down. as far the hfe stuff: yep, that's over my head.