Plausibly, but not confirmed. The HLK-LD2410C from Hi-Link matches the 24GHz frequency and presence-detection use case shown in the GreatScott! video. However, the video does not name a specific model, and no reference image was available to verify the pinout or PCB revision. Cross-check the datasheet before committing to a wiring layout.

Expect 20–45 days for standard AliExpress shipping from China for this component. AliExpress Choice sellers may ship in 15–25 days. EU or US warehouse stock for the HLK-LD2410C is uncommon, so most orders originate in China. If timeline matters, LCSC offers DHL shipping with 5–10 day transit at a higher price.

AliExpress buyer protection covers non-delivery and significant-not-as-described claims within 15 days of the delivery deadline. For a $5.35 order, opening a dispute is straightforward. However, there is no manufacturer warranty from Hi-Link on AliExpress purchases. If a board fails after the AliExpress dispute window closes, the $1.07-per-unit cost makes replacement the practical path.

Not natively. The HLK-LD2410C is a raw UART sensor module, not a Wi-Fi or Zigbee smart-home device. It requires a microcontroller host (ESP32, Arduino, etc.) to process its output and expose it to a smart-home platform. ESPHome has a well-maintained LD2410 component that supports HomeKit via Home Assistant and Google Home, which is the integration path shown in most DIY tutorials.

Yes — ESPHome has a dedicated LD2410 sensor component that communicates over UART and exposes motion and occupancy entities directly to Home Assistant. The HLK-LD2410C is one of the reference boards for that component. Configuration requires connecting TX, RX, VCC (3.3V or 5V depending on board variant), and GND to an ESP32 or similar host.

The HLK-LD2410C's stationary-presence (heartbeat) detection can keep lights on when someone is standing still on the stairs, which basic PIR sensors miss. This is actually an advantage over simpler motion-only radars. The sensitivity threshold for stationary presence is configurable via the Hi-Link PC tool or ESPHome parameters, so it can be tuned to avoid false triggers.

The HLK-LD2410C operates on 5V supply with 3.3V logic on its UART pins according to the Hi-Link datasheet. When connecting to a 3.3V microcontroller like an ESP32, no level shifter is typically needed on the RX line; however, some builders add a voltage divider on the module's TX line as a precaution. Verify the specific board revision you receive against the datasheet before powering up.

A single stair run typically uses 2–4 sensors depending on staircase length and detection zones. A 5-pack at $5.35 total ($1.07 per unit) covers most single-staircase projects with spares for experimentation. The 20-pack ($5.35 shown is for 5pcs — 20pcs pricing varies by seller) makes sense if you're outfitting multiple staircases or sharing with other makers. Extras are useful for bench testing before permanent mounting.