NPN and PNP BJTs use opposite voltage and current polarities. An NPN commonly switches near ground; a PNP commonly switches near the positive supply.
1. Set up the experiment
Choose NPN or PNP and inspect the emitter position and base-drive reference. Compare the sign of base-emitter voltage.
2. Connect the result to the equation
NPN: V_BE≈+0.7 V; PNP: V_BE≈−0.7 V
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
A PNP base must be below its emitter to turn on in this model. Pin order is package-specific; NPN and PNP do not imply a universal lead arrangement.
Circuit reference diagram
Continue this learning path
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.
Frequently asked questions
Can I use every experiment on NavSprout?
Yes. The course guides and workbenches run on NavSprout.
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.
Do I need hardware or a login?
No hardware or account is needed. The 3D view needs WebGL, while diagrams, controls and static lessons remain available as alternatives. Progress is stored in this browser and can be exported.
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.
