A bridge of four diodes turns AC into pulsating DC by flipping the negative half-cycles. A capacitor then smooths it into nearly steady DC – the heart of every traditional linear power supply.
How to use the Bridge Rectifier Calculator
- Secondary RMS voltage
- Diode forward drop
- Load resistance
- Mains frequency
- Smoothing capacitance (0 = none)
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter the transformer secondary RMS voltage, diode drop, load resistance, mains frequency and the smoothing capacitor (0 for none).
Inputs explained
| Field | What to enter |
|---|---|
| Secondary RMS voltage | Units: V, mV, kV, µV, MV |
| Diode forward drop | Units: V, mV, kV, µV, MV |
| Load resistance | Units: Ω, kΩ, MΩ, mΩ |
| Mains frequency | Choose one: 50 Hz, 60 Hz |
| Smoothing capacitance (0 = none) | Units: µF, mF, nF |
What each result means
- Peak output voltage = sqrt(2)×[Secondary RMS voltage] – 2×[Diode forward drop]
- DC load current = [DC output voltage]÷[Load resistance]
- Peak inverse voltage per diode = sqrt(2)×[Secondary RMS voltage] – [Diode forward drop]
Example values
How the main result changes when Secondary RMS voltage changes and everything else stays at the example values above:
| Secondary RMS voltage (V) | DC output voltage (V) |
|---|---|
| 6 | 6.9243 |
| 9 | 11.0705 |
| 12 | 15.2167 |
| 15 | 19.3629 |
| 18 | 23.5091 |
| 24 | 31.8016 |
Formula
V_p = √2·V_rms, V_DC = 2(V_p − 2V_d)/π (no capacitor), V_ripple ≈ I_DC/(2fC), PIV = V_p − V_d
Worked example
Inputs — Secondary RMS voltage: 12 V; Diode forward drop: 0.7 V; Load resistance: 100 Ω; Mains frequency: 50 Hz; Smoothing capacitance (0 = none): 2,200 µF.
Results — Peak output voltage = 15.5706 V; DC output voltage = 15.2167 V; DC load current = 0.1522 A; Peak-to-peak ripple = 0.7078 V; Ripple factor = 0.0134; Peak inverse voltage per diode = 16.2706 V.
Key terms
- Full-wave rectifier
- Uses both half-cycles of AC.
Frequently asked questions
Why two diode drops?
Current always flows through two diodes of the bridge.
What is the ripple frequency?
Twice the mains frequency.
How big should the capacitor be?
Large enough that ripple is a small fraction of V_DC – roughly I/(2f·V_ripple).
What is ripple factor?
AC RMS ripple divided by DC output; 0.483 without filtering.