536 Transistor help

[metulmykul]

Ages ago, I grabbed a couple of transistors on the off chance that i could use them in something.

Well, i finally got around to trying them and really like them and want some more. Trouble is i can't remember where i got them nor can i find a thing online re: data sheet.

They are a 536 (NPN silicon) marked 536 with FOK marked under that. The casing is about half the size of a normal TO92 and they have a truckload more gain than any of the 2SC536s that i have laying around.

Anybody shed any light or know where i might get some?

cheers

[11 Gauge]

Is there any kind of symbol or logo near the word FOK?

You say that they aren't quite a TO92 case - is it also a bit more angular than hemispherical when viewed from above?

Lastly, what is the pinout? Is it EBC, CBE, or something different? This may give a clue as to what series the little buggers might be.

Very odd. The case size seems to indicate a standard switching general purpose tranny, but your reported higher Hfe indicates that it was probably designed for other purposes.

Oh - can you explain the circuit(s) that you are using them in, and how you have them wired/biased up?

[metulmykul]

hang on a second 11 Gauge and i'll grab a pic...

[metulmykul]

The actual face reads

536
FOK*

The dot sits between the text at the end, almost as above.

It looks like a trimmed down TO 92 case. Pinout is the same as the other 536s i have: ECB BCE.

They are for a Univox/Unicord Super-Fuzz circuit. Normally i use 2SC828 or 2SC536. The gain on the 2SC jobs is anywhere between 90 and 250 while these FOK numbers are all around 335. They actually create a totally new beast in my opinion. Clear with a Big fat tight bottom end. You should see them on a scope...3 or 4 harmonics happening.

[metulmykul]

Sorry about the quality, still don't know how to do close ups!

The 'standard' 536 is on the right.

[11 Gauge]

I have a gut feeling that they are obsolete, seeing the pics, noting the pinout, and seeing the labeling on the tranny.

I'm nearly convinced that the FOK designation is a code for the factory that made the units. Perhaps the only other telltale breadcrumb trail would be to find some gear that they were used in (unlikely that they were pedals - probably radios, TV's, etc.).

Are you saying that they have an actual Hfe of ~335? If so, is this a nominal figure? There are certainly quite a few BJT's that have an average Hfe around that number. They might not be dead on, but at least be a current production unit.

It sounds like you need something that's a little hotter than a 2N3704 and a little cooler than a 2N5088.

I actually just put a set of 2N3704's in a Colorsound Overdriver replica build, and they sounded tremendous! They also have the ECB pinout, as well. I'd say that they're worth a shot.

[metulmykul]

Thanks 11 Gauge.

That's the actual Hfe (according to my dmm) and i have no idea what they may have been used in.

I did some digging and found that i had ordered 6 x 2SC536 trannys from Futurelec earlier in the year and i'm sure that these are what turned up.

I know i have some 5088s and I might do some pin bending etc and try something with a similar 'heat' as it sounds too good not to pursue.

thanks again.