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# Transistor bias calculator

Biases a BJT as a saturated switch or a divider-biased amplifier, with base resistor, drive current, Q-point, and stability ratio.

Fill the fields to bias the stage.

This is a DC calculator with fixed constants: Vbe 0.7 V at turn-on and Vce(sat) 0.2 V when saturated. Real Vbe falls about 2 mV per kelvin and real Vce(sat) varies with current, so hot or cold circuits will drift from these numbers. It does not compute AC gain, input impedance, or frequency response, and it is no substitute for the datasheet: hFE is a spread across parts, which is exactly why switch mode leans on overdrive and amplifier mode reports a stability ratio instead of trusting hFE.
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