Description
The Circuitron 5521 BD-1HD Block Occupancy Detector is a heavy-duty current-sensing single-output block detector — like the BD-1 but with higher current capacity for layouts with multiple sound-equipped locomotives in a block.
What it does: Provides one logic-level occupancy output for an isolated block. Higher current rating than the standard BD-1 — handles the larger combined current of multiple modern sound-equipped diesels without saturating.
- Detection method: Current sensing (heavy-duty)
- Output: Single logic-level occupancy signal
- For: Blocks that may hold multiple sound-equipped diesels simultaneously
- Circuitron SKU: 5521 (Walthers 800-5521)
About Circuitron: A USA-made model-railroad electronics specialist (Maryville, Illinois) founded in the 1970s. Famous for the industry-standard Tortoise slow-motion under-table switch machine and its surface-mount cousin the SMAIL. The full range covers detection (block detectors, Opto-Sensor grade-crossing logic), automation (auto-reversers, external relays, twin-coil alternators), signal / lighting electronics (alternating flashers, ditch-light oscillators, strobe drivers), power supplies, and a complete set of Tortoise / SMAIL replacement parts plus the solderless ZipZ connection system. Most circuits work with AC, DC, or DCC track power unless specifically noted otherwise.
In stock at Oakville Model Trains Depot.