Bridge Rectifier Calculator
Calculate DC output voltage from AC input voltage using a bridge rectifier
Volts RMS (V)
How to Use This Calculator
Enter AC Voltage
Enter the AC input voltage in RMS (Root Mean Square) volts. This is the standard AC voltage measurement (e.g., 12V RMS, 120V RMS).
Calculate Output
Click the calculate button to get the peak voltage and DC output voltage. The calculator accounts for diode forward voltage drops.
Understand Results
The DC output voltage is lower than peak voltage due to diode drops. For smooth DC, you'll need to add a filter capacitor.
Formula
Vpeak = VRMS × √2
VDC = Vpeak - 2 × Vf
Where:
- Vpeak = Peak voltage (V)
- VRMS = RMS (Root Mean Square) voltage (V)
- VDC = DC output voltage (V)
- Vf = Diode forward voltage drop (typically 0.7V per diode)
- √2 ≈ 1.414
Example 1:
AC Input = 12 V RMS
Vpeak = 12 × √2 = 12 × 1.414 = 16.97 V
VDC = 16.97 - (2 × 0.7) = 16.97 - 1.4 = 15.57 V
Example 2:
AC Input = 120 V RMS
Vpeak = 120 × √2 = 169.7 V
VDC = 169.7 - 1.4 = 168.3 V
About Bridge Rectifier Calculator
The Bridge Rectifier Calculator is a free online tool that helps you calculate the DC output voltage from an AC input voltage when using a bridge rectifier circuit. A bridge rectifier is a circuit that converts alternating current (AC) to direct current (DC) using four diodes arranged in a bridge configuration. This calculator accounts for diode forward voltage drops and provides accurate DC output voltage calculations for power supply design.
When to Use This Calculator
- Power Supply Design: Design AC-DC converters and power supplies for electronic devices
- Transformer Calculations: Determine transformer secondary voltage needed for desired DC output
- Battery Chargers: Calculate rectifier output for battery charging circuits
- Educational Purposes: Learn about AC-DC conversion and rectifier circuits
- Circuit Analysis: Analyze existing rectifier circuits and verify component selection
Why Use Our Calculator?
- ✅ Accurate Calculations: Accounts for diode forward voltage drops (typically 0.7V per diode)
- ✅ Peak Voltage Display: Shows both peak and DC output voltages
- ✅ Easy to Use: Simple interface requiring only AC input voltage
- ✅ Educational: Includes formulas and examples for learning
- ✅ Free Tool: No registration or payment required
- ✅ Instant Results: Get calculations in seconds
Common Applications
Power Supplies: Most electronic devices use bridge rectifiers to convert wall outlet AC (120V or 240V) to DC for internal circuits. A 12V AC transformer with a bridge rectifier produces approximately 15.6V DC (before filtering), which can then be regulated to stable 12V DC.
Battery Chargers: Battery chargers use bridge rectifiers to convert AC to DC for charging batteries. The rectifier output is filtered and regulated to the appropriate charging voltage for the battery type.
Motor Control: DC motors often require rectified AC power. Bridge rectifiers provide full-wave rectification, which is more efficient than half-wave rectifiers.
LED Drivers: LED lighting systems often use bridge rectifiers to convert AC power to DC for LED operation. The rectified voltage is then regulated to match LED requirements.
Tips for Accurate Results
- Always enter AC voltage in RMS (Root Mean Square) - this is the standard AC voltage measurement
- The calculator assumes standard silicon diodes with 0.7V forward voltage drop
- For Schottky diodes (lower Vf), the DC output will be slightly higher
- Add a filter capacitor to smooth the DC output and reduce ripple
- For smooth DC, capacitor should be sized based on load current and acceptable ripple
- Actual DC output will be slightly lower under load due to transformer regulation and losses
Frequently Asked Questions
What is a bridge rectifier?
A bridge rectifier is a circuit that converts AC to DC using four diodes arranged in a bridge configuration. It provides full-wave rectification, meaning it uses both halves of the AC waveform, making it more efficient than half-wave rectifiers.
Why is the DC output lower than peak voltage?
The DC output is lower because each diode has a forward voltage drop (typically 0.7V for silicon diodes). In a bridge rectifier, current flows through two diodes at a time, so the total drop is 2 × 0.7V = 1.4V.
Do I need a filter capacitor?
Yes, for smooth DC output, you need a filter capacitor. Without it, the output will have significant ripple (voltage variation). The capacitor smooths out the pulsating DC from the rectifier.
What's the difference between RMS and peak voltage?
RMS (Root Mean Square) voltage is the effective voltage that produces the same power as DC. Peak voltage is the maximum voltage in the AC waveform. Peak voltage = RMS voltage × √2 (approximately 1.414).
Can I use this for three-phase AC?
This calculator is for single-phase AC. Three-phase bridge rectifiers use six diodes and produce different DC output characteristics. You would need a specialized three-phase rectifier calculator.