C

AC to DC Converter

Convert AC RMS to DC output for half-wave, full-wave, and bridge rectifiers. Configure diode drops, frequency, and smoothing capacitor to estimate ripple for practical designs.

Calculate Your AC to DC Output

AC Input (Vrms)
Rectifier Type
Diode Forward Drop (V)
Input Frequency (Hz)
Load Current (A)
Smoothing Capacitor (ยตF)

Your Results

15.571 V
Approx. DC Output (no-load)
Peak After Diodes
15.571 V
Ripple Frequency
100 Hz
Estimated Ripple (Vpp)
2.273 V
Approx. Range (Vmin ~ Vmax)
14.434 ~ 16.707 V

Key Concepts: Peak, Vdc and Ripple

Peak Voltage

Vpeak โ‰ˆ Vrms ร— โˆš2 (sinusoidal)

  • โ€ข Subtract diode drops
  • โ€ข Transformer regulation matters
Rectifier Type

Half-wave vs full-wave/bridge

  • โ€ข Full-wave doubles ripple freq
  • โ€ข Bridge has 2 diode drops
Smoothing Capacitor

Higher C โ†’ lower ripple

  • โ€ข Ripple โˆ Iload/(Cร—frect)
  • โ€ข ESR impacts ripple
Safety

Mains voltages can be lethal

  • โ€ข Use isolation transformer
  • โ€ข Discharge capacitors safely

How to Convert AC to DC

Formulas

Peak: Vpeak โ‰ˆ Vrms ร— โˆš2 โˆ’ Vdiodes
Ideal DC (no ripple): Vdc โ‰ˆ Vpeak
Ripple: ฮ”V โ‰ˆ Iload / (C ร— frect)

Calculation Steps:

  1. 1
    Determine rectifier type
    Half-wave / full-wave / bridge
  2. 2
    Compute Vpeak
    Vrms ร— โˆš2 โˆ’ diode drops
  3. 3
    Estimate DC and ripple
    Use capacitor and load current

Important Considerations

โš ๏ธ Electrical Safety

Mains and DC rails can be dangerous. Follow proper isolation, fusing, and discharge procedures.

Diode Drops

Account for 1 or 2 diode drops depending on topology

  • โ€ข Silicon ~0.7 V
  • โ€ข Schottky ~0.2โ€“0.4 V
  • โ€ข Temperature dependent
Load Regulation

Heavier load increases ripple and lowers Vdc

  • โ€ข Consider headroom
  • โ€ข Use larger C
  • โ€ข Or add regulator
Frequency

Full-wave doubles ripple frequency

  • โ€ข 50 Hz โ†’ 100 Hz
  • โ€ข 60 Hz โ†’ 120 Hz
  • โ€ข Higher f โ†’ lower ripple
Thermal

Diode and regulator dissipation

  • โ€ข Provide heatsinking
  • โ€ข Check power ratings
  • โ€ข Consider efficiency

Example Cases

Case 1: 230 Vrms to DC (Bridge)

Input: Vrms 230, bridge, 2ร—0.7 V diodes, C=470ยตF, I=0.2A, 50 Hz
Result: Vdc โ‰ˆ 230ร—โˆš2โˆ’1.4 โ‰ˆ 323V (no-load); ripple โ‰ˆ I/(Cร—2f) โ‰ˆ 0.2/(470e-6ร—100) โ‰ˆ 4.26Vpp

Case 2: 12 Vrms to DC (Half-wave)

Input: Vrms 12, half-wave, 0.7 V diode, C=2200ยตF, I=0.5A, 60 Hz
Result: Vdc โ‰ˆ 12ร—โˆš2โˆ’0.7 โ‰ˆ 16.3V (no-load); ripple โ‰ˆ I/(Cร—f) โ‰ˆ 0.5/(2200e-6ร—60) โ‰ˆ 3.79Vpp

Pro Tips & Notes

  • Leave regulator headroom: Vdc under load should exceed dropout.
  • Use ripple current rated capacitors; check ESR and temperature.
  • Prefer Schottky diodes for lower drop at low voltages.
  • Derate transformer; consider mains tolerance (ยฑ10%).

Frequently Asked Questions

How do I convert AC RMS voltage to DC output?
For ideal full-wave rectification, Vdc โ‰ˆ Vrms ร— โˆš2 minus diode drops. Real circuits have ripple and losses; use capacitor and load to estimate ripple.
What's the difference between half-wave and full-wave rectifiers?
Half-wave uses one diode and rectifies half cycles (higher ripple). Full-wave/bridge uses more diodes to rectify both halves, producing higher Vdc with lower ripple.
How do diode voltage drops affect DC output?
Each conducting diode reduces the peak by about 0.7 V (silicon) or ~0.2โ€“0.4 V (Schottky). Bridges conduct through two diodes per half-cycle, subtracting roughly 1.4 V total.
How do I estimate ripple with a smoothing capacitor?
Ripple โ‰ˆ Iload / (C ร— frect). For full-wave at 50 Hz mains, frect โ‰ˆ 100 Hz. Increase capacitance or reduce load current to reduce ripple.
Is Vrms ร— โˆš2 always valid for peak voltage?
It assumes a sinusoidal input. Non-sinusoidal or regulated supplies deviate. Also subtract diode drops and consider transformer regulation.

Related Calculators

AC to DC Converter - RMS to DC, Rectifier & Ripple