AC Rectifier Diode Selection

Question

Problem: AC Rectifier Diode Selection. Solve this hands-on electronics task on EWskills.

Accepted Answer

1. Component Purpose

The board receives 24VAC from a transformer. AC voltage swings both positive and negative, but the board’s circuits need steady DC. A rectifier diode converts AC to DC by allowing current to flow in only one direction.

The peak voltage of 24VAC is 24 × 1.414 = ~34V peak. In a bridge rectifier, each diode sees the full peak voltage in reverse. With safety margin, the diode needs ≥200V reverse rating to handle surges and transients on the AC line reliably.

Required: General Purpose Rectifier · ≥1A · ≥200V · SMA · SMD · −40°C to +125°C · RoHS

2. How to Find It on DigiKey

Go to DigiKey.com → Discrete Semiconductor Products → Diodes → Rectifiers → Single Diode

Apply these filters:

Diode Type (Technology) → Standard
Voltage - DC Reverse (Vr) → 200V or higher
Current - Average Rectified (Io) → 1A or more
Supplier Device Package → SMA (DO-214AC)
Part Status → Active

Tip: For AC rectification, always calculate peak voltage (Vrms × 1.414) and add generous margin. AC mains can have transient spikes well above normal peak.

3. Key Specifications & What They Mean

Specification	Required	Why
Diode Type	General Purpose Rectifier	Standard rectifier for AC-to-DC conversion.
Avg Current (Io)	≥1A	Matches the rectifier section’s current.
Reverse Voltage (Vr)	≥200V	24VAC peak is ~34V; 200V covers surges.
Package	SMA	Standard SMD package for 1A diodes.
Temp Range	−40°C to +125°C	Industrial operating conditions.
RoHS	Yes	Compliance required.

4. Selecting a Safe, Production-Ready Part

The filtered list will show many matching parts. Before you pick one, check: Is it Active? Is stock available? Is the manufacturer reputable? Is a datasheet available?

Full checklist: How to Select a Safe, Production-Ready Component — EWskills Guide

5. Filtered DigiKey Link

➡ View Matching Parts — Rectifier, SMA, ≥1A, ≥200V

31. AC Rectifier Diode Selection