Working on a board from the 80s and there is this old Siemens transistor. I was assuming this is a BC337 but it has the 40 above. Other similar boards have BC337-40 transistors written with the 40 after the 337 in the typical way.
Would you say this is a BC337 or a BC337-40?

 

Hello,

It is likely a 2sc337. The 2s is often omitted.

Bertus

 

Thanks for the reply. I looked it up and found this:
"BC" is typically a prefix used by European manufacturers to identify a transistor, while "2SC" is a similar prefix used by Japanese manufacturers,
This transistor has a Siemens symbol on it so I think it is a BC. I learned something today.

 

The transistor is house marked it has an hFE of 40 very close to the ONsemi BC337 40

 

The transistor is house marked it has an hFE of 40 very close to the ONsemi BC337 40

Huh???

Where do you get that notion from?

hFE varies so much with operating condition that it would be pointless to make the effort to mark each transistor with what it happened to be under some particular operating condition.

The additional markings on almost all semiconductor packages are for tracking things like manufacturing date, country of origin, and the like. Some times they are for custom binning purposes, but that's actually pretty uncommon. When they are marked by the manufacturer, that information is usually part of the part number.

Plus, if it had an hFE of 40, it wouldn't even meet the minimum hFE for the BC337 under any conditions within it's operating range.

Having said that, it could be that it does indicate a Siemens BC337-40, which has a nominal hFE of 400 (250 to 630) at an Ic of 100 mA.

I haven't been able to find any documentation for how Siemens marked its transistors in that package, but what the TS is showing would not be unreasonable.

 

Thanks very much for the detailed response! Somehow it didn't occur to me until just now that I could just measure the gain and the difference should be clear between the base 337 and the -40. I will do this and report back in the name of science.

 

Thanks very much for the detailed response! Somehow it didn't occur to me until just now that I could just measure the gain and the difference should be clear between the base 337 and the -40. I will do this and report back in the name of science.

Oh, I was assuming that the reason you were working on the board and had removed that transistor was because you had concluded that it was bad and needed to be replaced.

If it is part of a complementary pair (was it the BC237???), looking at the markings on that other transistor might shed some light.

 

Okay right on. They are not part of a complimentary pair. It is part of an 80s automotive ECU that is not working and I am replacing all of the transistors and electrolytic capacitors, whether they are burned out or not. There are about eight of these all the same and I'm guessing the good looking ones still work. Thanks again

 

What vehicle make and model did that ECU came from?

 

Planar,
The data sheet Page 1 shows Type. On that list there are 3 categories specified on the datasheet.
The BC337-40 is the correct category classification, I am confirming what you mentioned.
The factory markings for 3 different hFE categories. Page 3 DC current gain. Testing would further conclude this.
The 40 refers to the hFE category. Identifying what is shown in the picture.

 

Okay I got my multimeter and did the HFE test and it measured 275. That is beyond the maximum range for the regular BC337 and at the low end of the BC337-40 from the Siemens datasheet. I would take this as conclusive that these unusual Siemens markings show it to be the BC337-40.

 

Now I've noticed that other Siemens components are also marked in this way and it seems I misidentified them:

so it seems this is a BC327-16
and this is a BC547C and not a BC547
and a BC337-25