Devices & Interactive Circuit Tools

🎯 Tool Purpose
These calculators help you verify your solutions and build intuition for device behavior. Use them after attempting problems manually—not before.

🔋 Diode Bias Classifier

Determine if a diode is forward biased, reverse biased, or below threshold

Result will appear here

Enter voltage values and click the button to classify diode state.

🔬 Exam Application
Silicon: Vth ≈ 0.7 V | Germanium: Vth ≈ 0.3 V
Forward bias starts conducting only when V > Vth. Below threshold, current is negligible.

⚡ Rectifier Performance Calculator

Calculate DC output, efficiency, and ripple factor

Results will appear here

Enter rectifier parameters and click calculate to see DC output voltage, power, efficiency, and ripple factor.

❌ Common Calculation Error
Students confuse: "Vm = 220 V means peak voltage" WRONG.
220 V is usually RMS voltage. Peak voltage Vm = √2 × VRMS = 220√2 ≈ 311 V.
Always check whether given voltage is RMS or peak.

💡 LED Band Gap to Wavelength Converter

Convert between band gap energy and emitted wavelength

🧠 Quick Formula
λ (nm) = 1240 / Eg (eV)
This is the most frequently used formula for LED questions in NEET/JEE Main.
Results will appear here

Enter band gap energy to calculate emitted wavelength and identify LED color.

Wavelength Range (nm) Color Typical Eg (eV) Material
380-450Violet/Blue2.75-3.26GaN
450-495Blue2.5-2.75InGaN
495-570Green2.18-2.5GaP, InGaN
570-590Yellow2.1-2.18GaAsP
590-620Orange2.0-2.1GaAsP
620-750Red1.65-2.0AlGaAs, GaAsP
750-1000Infrared1.24-1.65GaAs

🔌 Logic Gate Simulator

Test logic gate operations with different input combinations

Output will appear here

Select gate type and input values to see the output.

🔬 NEET Logic Gate Strategy
Most asked: NAND and NOR as universal gates.
Trick: NAND = NOT + AND, NOR = NOT + OR
Remember: NAND and NOR produce opposite of AND/OR respectively.

XOR: Output is 1 only when inputs are different.

Truth Tables Quick Reference

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AND Gate

0 AND 0 = 0
0 AND 1 = 0
1 AND 0 = 0
1 AND 1 = 1

OR Gate

0 OR 0 = 0
0 OR 1 = 1
1 OR 0 = 1
1 OR 1 = 1

NOT Gate

NOT 0 = 1
NOT 1 = 0

NAND Gate

0 NAND 0 = 1
0 NAND 1 = 1
1 NAND 0 = 1
1 NAND 1 = 0

NOR Gate

0 NOR 0 = 1
0 NOR 1 = 0
1 NOR 0 = 0
1 NOR 1 = 0

XOR Gate

0 XOR 0 = 0
0 XOR 1 = 1
1 XOR 0 = 1
1 XOR 1 = 0

Special Purpose Diodes - Quick Reference

LED (Light Emitting Diode)

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Working: Forward biased p-n junction where electron-hole recombination emits photons.

Material: Direct band gap semiconductors (GaAs, GaP, InGaN)

Key Formula: λ = 1240/Eg (nm)

Applications: Displays, indicators, optical communication

Exam Trick: LED emits light in forward bias ONLY. Threshold voltage higher than normal diode (1.5-3 V).

Photodiode

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Working: Reverse biased p-n junction. Light generates electron-hole pairs, increasing reverse current.

Key Point: Works in reverse bias (opposite of LED)

Current: I = Idark + Iphoto (proportional to light intensity)

Applications: Light detectors, optical communication receivers, solar cells

Students confuse: "Photodiode works in forward bias" WRONG.
Photodiode operates in reverse bias for faster response.

Solar Cell (Photovoltaic Cell)

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Working: p-n junction with NO external bias. Light generates voltage and current.

Key Difference from Photodiode: Solar cell is unbiased. It generates its own voltage.

Efficiency: η = (Pout/Pin) × 100% (typical: 15-22% for Si cells)

Voc: Open circuit voltage (~0.5-0.7 V per cell)

NEET asks: "What is the typical voltage of one silicon solar cell?"
Answer: ~0.5-0.6 V (NOT 1.1 eV, which is band gap)

Zener Diode

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Working: Operates in reverse breakdown region. Maintains constant voltage.

Zener Voltage VZ: Specific voltage at which breakdown occurs (available: 3.3V, 5V, 6V, 9V, 12V, etc.)

Application: Voltage regulation (stabilizes fluctuating input voltage)

Key Formula: RS = (Vin - VZ)/IZ

Exam Strategy: Always check if Zener is in breakdown region (V > VZ in reverse bias). If not, it acts like a normal diode.
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