Electronics > Beginners
Controversy on Transistor Testing: Can't be both!
billbyrd1945:
Here's a drawing that shows how I understand the test to be done. Several videos show it done this way. Conflicting videos show that the last transistor in the drawing should be OL so that the middle and right pins would pass no voltage in either direction. One method condemns my transistors while the other says they're good. What do you guys say? I have no schematic. The markings are all I have.
ataradov:
According to a quick search, 13005D appears to have a built-in diode. That's what you are measuring in the last two pictures.
And the pinout makes sense, it is B-C-E (left to right).
nsrmagazin:
--- Quote from: ataradov on November 26, 2018, 04:34:10 am ---According to a quick search, 13005D appears to have a built-in diode. That's what you are measuring in the last two pictures.
And the pinout makes sense, it is B-C-E (left to right).
--- End quote ---
Also what you are looking for is that both video options are true. You have to check for your transistor and see which pin is what. Its not a guarantee that it will always be the same.
billbyrd1945:
Okay guys. I get what you're saying. This is what I was just about to post:
In this video at 11:50, Lorton shows a convincing diagram that inhibits flow from C to E in either direction for NPN or PNP. Are you saying this does not apply in my application? (I think that's what the two of you are telling me.) Just trying to learn. Thanks!
(Please see image below from video)
nsrmagazin:
What my post told you is that not always the pins are "B, C, E" = pin 1, pin 2, pin 3. You have to check the datasheet for your current transistor. The other post told you that there is a diode connected with the transistor and when you measure you are not actually measuring the "NPN" transition of the transistor, but you are measuring the "PN" transition of the diode. A transitor is a "double diode" a diode is a "half transitor" in terms of how they are built.
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