| Electronics > Beginners |
| Help Understanding PNP transistors |
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| AngraMelo:
Hello guys, I have been studying the theory and the practical side of electronics for a while. As Im doing everything on my own, I have large knowledge gaps spread out on different levels. When I see explanations about transistor, they almost always use the NPN type to explain saturation, Vce and general calculations. So I ended up having a lot of PNP theory to study and understand (the negative voltages and everything makes it harder for me) When Im calculating the power dissipation of a transistor, I assume the formula is: P= (Vce)x(Ie) So I know that if I put 10V at the base of a NPN, and its collector is at 20V, ill get around 11Vce. How does that work for a PNP? is it exactly the same? So if I have the emitter at 20V and I apply 10V to the base I will get Vec = 11V? |
| eev_carl:
If you're talking about a common emitter, you may want to check out this recent thread. It's on NPN, but the forum warned me about putting 1V at the base. I imagine they'd have a problem with 10V as you'd need even more resistance (100k?) to produce the microamps of Ib. https://www.eevblog.com/forum/beginners/question-on-npn-logic-inverter-from-textbook/ |
| AngraMelo:
My case is only theoretical, but just for reference I was thinking about big power transistors. Thank you for your input! |
| Audioguru again:
The forward Vbe bias voltage of a transistor is 0.6V for low currents and is maybe 1.5V for high currents. If the emitter of a PNP transistor is at +20V then its emitter will also be +20V when the transistor is turned off and the base will be at +18.5V to +19.4V when it is turned on. |
| langwadt:
just flip everything up side down |
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