Project File
Auto-Off Timer
A compact mains-connected auto-off timer built around the C005 timer IC, a relay output stage, and a transformerless capacitive power supply — no bulky adapters required.
Build Summary
The timer counts down a user-set period and switches off the load via a relay. The entire circuit runs from a capacitive dropper supply directly off mains, keeping the footprint to a single compact PCB.
- C005 timer IC driving a single-pole relay for load switching
- Capacitive power supply (X-rated cap dropper) — no transformer
- Onboard Zener regulation for stable 5 V logic rail
- Preset resistor network for fixed time intervals (15 / 30 / 60 min)
- LED indicator shows active countdown state
- Compact single-layer PCB fits a standard wall-plate enclosure
Technical Specs
| Timer IC | C005 (or equivalent NE555 variant) |
| Power Supply | Capacitive dropper, 230 V AC in |
| Logic Rail | 5 V DC via Zener regulator |
| Relay Output | 5 V coil, 10 A / 250 V AC contacts |
| Time Ranges | 15 min, 30 min, 60 min (preset) |
| Target Cost | USD 6 synthetic BOM |
Project Images
