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Measuring hfe of "P2N2222A" varies wildly
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Benta:

--- Quote from: magic on November 05, 2021, 10:29:40 pm ---The measurement is performed at Ib=10µA (220k pullup to 2.9V IIRC) and the number displayed is simply 100x the collector/emitter current in mA.

--- End quote ---

Which is totally useless. Collector current is the important controlling parameter. Just supplying some current to the base and measuring the IC is laughable.
But the feature looks nice in the sales brochure.
magic:
I'm telling you that the collector current is literally displayed on your meter during the measurement so you can correlate it with plots in the datasheet to estimate performance at other bias conditions ;)

And that the current used is fairly reasonable for typical small signal transistors with typical β of 100~300 (ends up being 1~3mA).
Benta:
I understand completely what you're telling me.
I'm just saying that that's not an hFE measurement. It's just "something" that you can "correlate" with the data sheet.
The data sheet specifically lists the collector currents to be used for hFE measurement.
CatalinaWOW:

--- Quote from: Benta on November 06, 2021, 09:53:46 am ---I understand completely what you're telling me.
I'm just saying that that's not an hFE measurement. It's just "something" that you can "correlate" with the data sheet.
The data sheet specifically lists the collector currents to be used for hFE measurement.

--- End quote ---

The data sheet tells the current at which the manufacturer specifies hfe.  But hfe is a parameter that exists at all currents and temperatures.  And what the DMM reports is a very good approximation of hfe at one operating point.  Whether that number is useful depends on your application.  I agree that it is nearly useless for evaluating specification compliance.  At best it can say maybe yes or almost surely not.
armandine2:
regarding different subscripts  hFE and hfe - forward current gain CE config. V2 short circuited - I see from beginners video attached  that a large capacitor in parallel shorts the ac output, presumably for the dc gain measurement you would literally just short with a wire? (a beginner's question - tagged on here)


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