Description
The NCE 5240205 BD20 Block Detector is the BD20 — a current-sensing block detector for DCC layouts, isolated from the track (no direct electrical connection) and rated up to 20 A track power.
What it does: Detects DCC track current being drawn through a single track feeder — locomotives + any rolling stock with current-drawing wheel-sets. Magnetically isolated from the track (no electrical connection), so it's safe across high-current power districts. Needs no external power for simple detection. Output can drive the NCE AIU01 or Mini Panel input, or with external 5–12 V DC can directly drive an LED or relay.
- Type: Current-sensing block detector (DCC)
- Isolation: Magnetic — no direct electrical connection to track
- Power required: None for detection; 5–12 V DC for LED / relay output
- Track current rating: Up to 20 A DCC
- Drives: NCE AIU01, Mini Panel, external LED / relay
- NCE part: 5240205 (Walthers 524-205)
Tip: The BD20 is the standard NCE block detector — one per detection block. Connect the outputs to an AIU01 to feed block-occupancy data back to a JMRI computer via the USB Interface (5240223).
About NCE: NCE Corporation (USA) — a leading manufacturer of NMRA-compliant DCC systems, mobile decoders, accessory decoders, and automation electronics. NCE products are renowned for the Pro Cab and Power Cab throttles, the rugged D-series mobile decoders (D13 / D408 / D16), the Switch-It / Switch8 / Snap-It family of accessory decoders for stationary turnout control, the BD20 block detector, and a full cab bus / booster / circuit-breaker ecosystem. Most NCE products are also fully compatible with other NMRA DCC systems.
In stock at Oakville Model Trains Depot.