3 ms·
I believe this video contains is mistaken in its claim that, in the absence of a base current, PNP transistors (unlike NPNs) freely conduct current between emit
by mannykannot 4y ago
I believe this video contains is mistaken in its claim that, in the absence of a base current, PNP transistors (unlike NPNs) freely conduct current between emitter and collector, and that an increasing base current restricts this? IIRC, both types have a high impedance when unbiased, which is reduced as the base current increases, and the only operational difference is the polarity of the voltages for normal operation.
- greenbit 4y agoPolarity of the current, too. You have to pull current out of the base of a PNP transistor to get C-E current. If you pull the base of an NPN toward ground, that shuts down the C-E current, but if you pull the base of a PNP toward ground, that turns the C-E current up. Maybe they conflated grounding the base with "absence of base current"?
- mannykannot 4y agoThe direction of the currents simply follows from the polarity of the voltage in each case, but this section of the transcripts shows the presenter of the video is talking about the change of magnitude of the collector current in response to a changing base current: 6:02 an NPN bipolar is like a switch which is normally open. it won't conduct until a current is applied at its base terminal. PNP types on the other hand act in the opposite way they reduce the flow in relation to their base current.