Specs on old transistors, please?

With those obscure numbers, I would suggest you test them. If you increase Vce while monitoring the base to emitter voltage, when the base voltage reaches the valence voltage that is absolute Vceo for that temperature. Then using a current limited supply, for germanium I'd say

600-700 uA, increment the Vcb until the current reaches the level found when testing Vceo. That is usually about 20-50% higher than Vce. It applies when the transistor base is driven from a low impedance source.

For current, after you have established Vce max, go down to 10V and start incrementally increasing base current, when you fing the Hfe roilling off, you are getting close to Ic max.

For Pd you will need to get emperical data on junction temp. You measure the temp of the case without a heatsink, and plot the base emitter valence voltage against that, then do it with a heatsink. From that you extrapolate the die to case thermal resistance. Also remember Ge transistors limit at 100C not 200. You derate everything twice as fast.

Ideally, to simplify the math, use a huge capacity heat sink. Perhaps immerse it in water. As the valence voltage drops due to higher junction temp, the actual wattage dissipated at the time will yield the figures.When the valence indicates max junction temp, and the case is at 25C, you are at the absolute Pd. This is from where you derate running off a standard JEDEC/JANTX type data sheet.

Another hint: when the Hfe at a given current drops to about 60% or so of hfe you are about at Ic max.

If you got a sinewave SG, Ft is when gain drops to .707 of DC gain. Make it easy on yourself and use a resistive load.

I can give a bit more detail, but time prohibits. For comprehensive details there are textbooks, or even manuals for curve tracers could be of help.

JURB

Very interesting. Could you please define "valence voltage"? Google ain't too smart in that area. Thanks, mike

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Valence voltage is that intrinsic voltage drop of a diode, or in this case, a transistor. It varies inversely with temperature, and is closely related to the reading you get on your diode scale. Put your lighter on under the DUT and the voltage drops. In this case the heat is applied from the outside. The case temperature will be higher than the junction temp.

If the heat is emitted from the inside, the junction is hotter then the case. This is from whence we can derive the real figures.

So the .645V you read across a diode is the valence voltage at that current and temp. When driving the base of a transistor it is ever so much more complex.

What's more, 0.140 might be a valid forward reading, and in some devices it's not wise to test them in reverse. Even the 2 volts reverse might damage a Ge device. Some may even read leaky when they're good. Germanium transistors are not all that great except for one thing. They have low loss at lower voltage levels, like in battery powered stuff. Silicon devices outperform them hands down until we get to that intrinsic voltage drop. They have made great strides in silicon, but if the same effort were put into Ge, or even glass Ovonics, what might the result be ?

[glass ovonics is an anamorphic semiconductor, the technology was seemingly dropped after it introduction in the 1970s, very important facets of this technology have found their way into the manufacture of solar cells]

IIRC, glass ovonics was polarity independant also, and at the time it was demonstrated (yes it was) engineers were still having alot of fun having, for the first time, complementary semiconductors.

For about a decade they did, but a nonpolarized semi, not NPN nor PNP I think would have really put a craw in them. Twenty years before it was all tubes, well mostly.

Everybody thought in a negative ground sense, one of the most flagrant dismissals came with the Sony EXR series of RPTVs. It uses a negative supply for H deflection and as far as I can discern, the yokes are DC coupled.

" snipped-for-privacy@aol.com" bravely wrote to "All" (05 Oct 05 18:25:32) --- on the heady topic of "Re: Specs on old transistors, please?"

ZZ> From: snipped-for-privacy@aol.com ZZ> Xref: core-easynews sci.electronics.repair:344241

ZZ> With those obscure numbers, I would suggest you test them.

Those are likely "house numbers" but I think with a TO66 they might be similar to AD161 and AD162 complementary Ge audio output transistors.

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