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Electronics Calculators

Free online electronics calculators for resistors, LEDs, capacitors, and circuit design.

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Resistor Color Code

Decode 4-band and 5-band resistor color codes to find resistance and tolerance

Resistance

1.0 kΩ ±5%

Min: 950 Ω · Max: 1.05 kΩ

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LED Resistor Calculator

Calculate the current-limiting resistor value and power dissipation for LEDs

Required Resistor

R = 160 Ω

Power: 0.064 W

Resistor (Ω)

160

Nearest E12

180 Ω

Nearest E24

150 Ω

Power (W)

0.064

Capacitor Charge Calculator

Calculate charge time, voltage, and time constant for RC circuits

τ = RC Time Constant

τ = 0.100 s

Time to reach 63.2%: 0.100 s

τ (τ = RC)

0.10 s

5τ (Full Charge)

0.50 s

Target Time

0.10 s

C·R Product

0.100