MIL-STD-750-3 Transistor Testing

[MitYeltu]

I just want to check my sanity...

I am going to be testing some transistors in a lab very soon per the above mil std. The test methods range from Vce, Vbe, hfe and the breakdown voltages that are listed on the datasheet. The transistor at this point is irrelevant.

Here's what I need to understand. According to the mil std, the circuits are all drawn for PNP trnsistors in one configuration. That's fine. However, I will most,likely be testing NPN transistors. So, if I understand this right, all I need to do is reverse the polarity of the sources and test equipment (ammeter, voltmeter) in order to correctly perform the tests per this std. Is this right?

 

[berkeman]

I just want to check my sanity...

I am going to be testing some transistors in a lab very soon per the above mil std. The test methods range from Vce, Vbe, hfe and the breakdown voltages that are listed on the datasheet. The transistor at this point is irrelevant.

Here's what I need to understand. According to the mil std, the circuits are all drawn for PNP trnsistors in one configuration. That's fine. However, I will most,likely be testing NPN transistors. So, if I understand this right, all I need to do is reverse the polarity of the sources and test equipment (ammeter, voltmeter) in order to correctly perform the tests per this std. Is this right?

Is there a different standard for testing NPN transistors? It seems strange that the standard would leave it up to the tester's imagination to come up with the complementary test circuit setups. It's not that hard, but it could be error-prone.

 

[MitYeltu]

No, there is not a different methods for NPN. That's why I'm asking. I suspect it is merely a matter of reversing things - keep the emitter, collector and base where they are in the circuits, but simply reverse the polarity on the sources. However, as I said, I'm not positive on this and I really don't like burning the UUTs.

 

[berkeman]

I just found out that the standard is available for free download (I'd assumed it was copyrighted and needed to be purchased). Here is one source:

https://snebulos.mit.edu/projects/reference/MIL-STD/MIL-STD-750-3.pdf

And they mention that the PNP circuits are the only ones shown, and others will be used for NPN transistors:

4.2 Test circuits.
The test circuits shown in the test methods of this test method standard are given as examples which may be used for the measurements. They are not necessarily the only test circuits which can be used; however the manufacturer shall demonstrate to the Government that other test circuits which they may desire to use will give results within the desired accuracy of measurement. Circuits are shown for PNP transistors in one circuit configuration only. They may readily be adapted for NPN devices and for other circuit configurations.

And in the Notes for Figure 3011-1, they do say to reverse the sources for NPN transistors:

NOTES:
1. A PNP device is shown. For NPN types, reverse the polarities of the voltage and bias sources and zener diode

I think in general reversing the polarity of the sources should work for most testing of PNP/NPN transistors, but if you have a question about a particular circuit that you want to verify, go ahead and post the two versions here in this thread so we can double-check them.