Electronic Components
Electronic Components is a free interactive simulation from StudyFi Lab. It runs right in your browser, with no sign-up and nothing to install.
Diodes, LEDs, transistors and capacitors
Experiments
Diode
A diode lets current flow in one direction only — from the anode to the cathode. In forward bias the current starts once the voltage passes about 0.6–0.7 V (the knee of the characteristic); then it rises steeply while the diode voltage hardly changes, and the rest of the voltage drops across the resistor: I = (U − U_D)/R. In reverse bias the diode blocks the current.
Try this: Raise the source voltage from 0 V: up to 0.5 V almost no current flows, around 0.65 V the diode “opens”. Then turn the source to negative values.
LED and series resistor
An LED is a diode that gives off light. Its forward voltage V_F is higher — about 2.0 V for red, 2.2 V for green and 3.0 V for blue — and the larger the current, the brighter it shines. The current must not exceed I_max = 20 mA or the LED burns out, so it always needs a series resistor R = (U − V_F)/I.
Try this: Set 9 V and let the calculator find the resistor for the blue LED. Then make the resistor smaller than recommended and watch what happens.
Transistor as a switch
A small base current I_B controls a large collector current I_C. With no base current the transistor is off (cut-off). In the active region I_C = β·I_B, where β is the current gain (here 100). When β·I_B would be more than the load allows, the transistor saturates: U_CE falls almost to zero and it acts like a closed switch — the LED is fully on.
Try this: Close the base switch, set R_B = 100 kΩ and slowly raise U_B: watch I_C grow together with β·I_B and then stop in saturation.
Charging and discharging a capacitor
A capacitor does not charge instantly through a resistor: its voltage rises as u_C = U·(1 − e^(−t/τ)) while the current falls off. The time constant τ = R·C sets the pace — after one τ the capacitor reaches 63 % of the source voltage, and when discharging it drops to 37 %. After about 5τ the process is practically over.
Try this: Let the capacitor charge, then switch to discharge. Double R (10 kΩ → 20 kΩ) and check that τ and the whole process take twice as long.
Frequently asked questions
What is Electronic Components?
Electronic Components is a free interactive simulation from StudyFi Lab. It runs right in your browser, with no sign-up and nothing to install. Diodes, LEDs, transistors and capacitors
Is Electronic Components free?
Yes. Electronic Components is completely free. It works in the browser on computers, tablets and phones, and you do not need an account.
What can I explore in Electronic Components?
Diode, LED and series resistor, Transistor as a switch, Charging and discharging a capacitor.
What does the “Diode” experiment show?
A diode lets current flow in one direction only — from the anode to the cathode. In forward bias the current starts once the voltage passes about 0.6–0.7 V (the knee of the characteristic); then it rises steeply while the diode voltage hardly changes, and the rest of the voltage drops across the resistor: I = (U − U_D)/R. In reverse bias the diode blocks the current.
What does the “LED and series resistor” experiment show?
An LED is a diode that gives off light. Its forward voltage V_F is higher — about 2.0 V for red, 2.2 V for green and 3.0 V for blue — and the larger the current, the brighter it shines. The current must not exceed I_max = 20 mA or the LED burns out, so it always needs a series resistor R = (U − V_F)/I.
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