pinout for 2N5910?

[fogwolf]

I have some Fairchild 2N5910s in TO-106 packaging. All I can find is a datasheet with no pinout diagram (http://www.datasheetarchive.com/pdf-datasheets/DataBooks/Document524151.pdf) I know I could figure out at least the base pin with the diode tester on my DMM, but then wouldn't be certain about the other 2 pins. Short of just plugging it into a circuit and seeing if it works or not, is there any way to tell (or does anyone have a link to a pinout for this transistor)? My DMM also tests for hFE - will this only give a reading if it's connected to my DMM correctly or is this similar to the diode check in that so long as the base is connected correctly it will read the same with the collector and emitter switched either way?

[theehman]

Generally the emitter is the pin near the flat side of the transistor body.  Center would be base and the last is the collector.

[fogwolf]

I'll look more closely when I get home this evening but the case seems pretty round:

[theehman]

Sometimes there's a slightly flattened area on one side.  Check and report back.

[R.G.]

The base-emitter of almost all silicon transistors will break over like a zener at something less than 9V. The collector-base junction is always more than that. If you can identify the base, you can put 10K in series with a 9V battery and find the one that breaks. That's the emitter.

The forward gain of a silicon transistor is high. The reverse gain (swapping emitter and collector) is quite low. Easy to tell if you can measure gain.

[fogwolf]

Thanks for the tips. Also I'll check the packaging more closely for a flat end.

When you say "break over" you mean it will test as a closed/continuous circuit if I check it this way (I'd be testing for continuity between the 2 leads with the 9V and 10K resistor connected to the base), right?

[R.G.]

I mean it acts like a zener diode and lets current flow when the voltage across it gets bigger than the breakover voltage.

In fact, this is *exactly* what zeners are. Silicon transistors today are heavily optimized for high gain, low noise, low leakage, and high speed. These optimizations have the side effect of making the base-emitter junction have a low reverse breakdown voltage.

To perform this test, put a resistor of 2K  to 10K in series with the junction under test and apply 9V to 12V to the series combination. Measure the voltage across the transistor junction. If it's 0.4 to 0.7V, you have it forward biased; turn it around and measure again. If it's full battery voltage, it's the collector junction, If it's 5 -8V, it's the base-emitter.

[fogwolf]

Makes sense. Thanks again.

[fogwolf]

Generally the emitter is the pin near the flat side of the transistor body.  Center would be base and the last is the collector.

You were exactly right - thanks!