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The emitter current is defined by hfe and the base current not the load. The load does not "define" Iemitter.

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closed as unclear what you're asking by uint128_t, Enric Blanco, Dmitry Grigoryev, Voltage Spike, clabacchio Jul 7 '17 at 12:45

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ And the base current is defined by.. what? \$\endgroup\$ – Eugene Sh. Jul 4 '17 at 20:46
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    \$\begingroup\$ The emitter current is a function of the circuit the transistor is operating in, could be base current or could be load or both. \$\endgroup\$ – sstobbe Jul 4 '17 at 20:56
  • \$\begingroup\$ Who said that...? \$\endgroup\$ – Electrical Architect Jul 4 '17 at 20:59
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Thinking of current as being pulled versus pushed, or the other way around, is a bad idea. Such a mental model obscures the physics instead of illuminating it. Current flows when there is a applied voltage across something, and that something allows the current to flow.

Resistors are very predictable somethings since the current is always proportional to the applied voltage. The proportionality constant is the resistance (A = V / Ω).

Other somethings react differently and are non-linear. A transistor from collector to emitter is one of these. The current the device lets thru from collector to emitter is mostly a function of the base to emitter current, once about a volt is applied C-E. Still, it's the device that allows the current, and can only do so when a voltage is applied to it.

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Very strange question. It really doesn't matter if current is pushed or pulled, or if it flows from negative to positive or vice versa. If you remain consistent in your view, the math will work.

As far as the transistor (Bipolar I assume), the Emitter current is the sum of the base-emitter current and the collector-emitter current. Generally the collector-emitter current is a function of the base-emitter current and hFE (beta, gain).

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