In a simplified BJT model, a small base current controls a larger collector current. Collector current is also limited by the supply and collector load.
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SUPPLY5.00 V
CURRENT5.00 mA
OUTPUT3.90 V
TIME0.00 s
Live curve
Calculated outputSource waveformMarker = current time
In a simplified BJT model, a small base current controls a larger collector current. Collector current is also limited by the supply and collector load.
1. Set up the experiment
Increase base drive gradually. Watch collector current rise until the load, rather than gain, sets the limit.
2. Connect the result to the equation
I_C ≈ min(βI_B, (V−V_CEsat)/R_C)
Change one parameter at a time and keep the others fixed. Read the signed output and current, then use the curve to distinguish a steady relationship from a changing transient.
Initial supply
5.00 V
Initial current
5.000 mA
Initial output
3.900 V
3. Notice the limits
The relation I_C≈βI_B applies mainly in the active region. It cannot increase current beyond the limit imposed by the external circuit.
Circuit reference diagram
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Why it’s here
Electronics 101 makes a component change visible: an altered resistance changes a current, a capacitor changes a delay, and a sensor changes a decision. The course guide links each concept to its experiment.
Open Ohm’s law and predict the effect of doubling the voltage.
Change the control and compare the ammeter, curve and equation.
Try RC charging and use the time constant to explain the curve.
Return to the course guide to choose the next experiment.
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Are these circuit simulations exact?
They are analytic teaching models: ideal sources and switches, fixed diode drops, simple BJT gain and saturation, exponential RC behavior, and illustrative sensor curves. They are not a SPICE solver or construction verification.
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Which current direction is shown?
Moving markers represent conventional current, not electron drift. Their motion is illustrative and is not a measurement of charge velocity.
Model references and scope
Original NavSprout lessons use standard lumped-circuit relationships and explicitly simplified component models. Diagrams explain teaching topologies, while the breadboard probe explains socket continuity. The workbench is not a verified physical assembly plan.
