New answers tagged npn
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NPN BJT (PBHV8140Z) Incorrect Gain?
I imported the SPICE model under 'documentation' at your Nexperia link and ran a simulation with Ib=2uA, emitter grounded and Vce = 85V. Similar results. The collector current is suspiciously Vce-...
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Accepted
Is there a simpler astable multivibrator?
A single unijunction transistor (UJT) or programmable unijunction (PUT) can work as a relaxation oscillator. So can a neon bulb. So can a tunnel diode, but they are weird.
The most simple 1-device ...
- 23.2k
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Why are PNP transistors ON when the base voltage/current is LOW?
Trying to see the brilliant idea
Your question is highly relevant, as it delves into foundational circuit arrangements like complementary amplifier stages, high- and low-side switching circuits, ...
- 19.5k
9
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Why are PNP transistors ON when the base voltage/current is LOW?
These diagrams have some labels to help understand what's going on:
simulate this circuit – Schematic created using CircuitLab
The label \$V_{BE}\$ refers to the potential difference between ...
- 47.1k
2
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Why are PNP transistors ON when the base voltage/current is LOW?
The voltage isn't "low".
In both NPN and PNP cases there must be enough voltage to hit the Vbe forward bias voltage so enough base current passes through B-E junction.
If you think of the B-...
- 172k
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Challenge: build a microphone AGC circuit with two NPN BJTs as the only active components
If J1 is an n-channel, depletion-mode JFET, then D1 is backwards and biased incorrectly.
JFETs can have an n-type or p-type channel. In the n-type, if the voltage applied to the gate is negative with ...
- 23.2k
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Challenge: build a microphone AGC circuit with two NPN BJTs as the only active components
Varying the Re (R4) also shifts the DC bias point of Bjt in way the lower R4 the lower Dc voltage on collector.
So you have to adjust DC point so the Vcc limitation doesn’t clamp in widest input ...
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