51. AC SSR Heater Control

A heater in a temperature control system switches ON and OFF frequently — often hundreds of times per hour. Mechanical relay contacts would wear out quickly under this duty cycle.

A Solid State Relay (SSR) uses semiconductor switching (typically a TRIAC for AC loads) instead of mechanical contacts. This gives silent operation, no contact bounce, no mechanical wear, and extremely long life even with frequent switching.

Most AC SSRs use zero-cross switching — they turn ON only when the AC waveform crosses zero. This reduces EMI and inrush current on resistive loads like heaters.

Required: SSR · SPST-NO · AC Output · 5VDC input · 230VAC load · ≥5A · Safety approved

Go to DigiKey.com → Relays → Solid State Relays

Apply these filters:

• Output Type → AC
• Voltage - Input → Range includes 5VDC (e.g., 3–32VDC)
• Voltage - Load → 240VAC or higher
• Load Current → 5A or higher
• Circuit → SPST-NO (1 Form A)
• Part Status → Active

Tip:  SSR input voltage is usually a range (e.g., 3–32VDC), not a single value. Make sure 5V falls within the specified input range.

Important:  SSRs generate heat when conducting. For loads above 2–3A, always mount the SSR on a heatsink. Without it, the SSR can overheat and fail.

The filtered list will show 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

➡ View Matching Parts — AC SSR, 5V Input, 230VAC, ≥5A, SPST-NO