{"product_id":"circuitron-5521-bd-1hd-block-occupancy-detector","title":"Circuitron 5521 BD-1HD Heavy-Duty Block Occupancy Detector","description":"\u003cp\u003eThe \u003cstrong\u003eCircuitron 5521 BD-1HD Block Occupancy Detector\u003c\/strong\u003e is a \u003cstrong\u003eheavy-duty current-sensing single-output block detector\u003c\/strong\u003e — like the BD-1 but with higher current capacity for layouts with multiple sound-equipped locomotives in a block.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat it does:\u003c\/strong\u003e 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.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDetection method:\u003c\/strong\u003e Current sensing (heavy-duty)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOutput:\u003c\/strong\u003e Single logic-level occupancy signal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFor:\u003c\/strong\u003e Blocks that may hold multiple sound-equipped diesels simultaneously\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCircuitron SKU:\u003c\/strong\u003e 5521 (Walthers 800-5521)\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cstrong\u003eAbout Circuitron:\u003c\/strong\u003e A USA-made model-railroad electronics specialist (Maryville, Illinois) founded in the 1970s. Famous for the industry-standard \u003cstrong\u003eTortoise\u003c\/strong\u003e slow-motion under-table switch machine and its surface-mount cousin the \u003cstrong\u003eSMAIL\u003c\/strong\u003e. 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 \u003cstrong\u003eZipZ\u003c\/strong\u003e connection system. Most circuits work with AC, DC, or DCC track power unless specifically noted otherwise.\u003c\/p\u003e\u003cp\u003eIn stock at Oakville Model Trains Depot.\u003c\/p\u003e","brand":"Circuitron","offers":[{"title":"Default Title","offer_id":45098470637750,"sku":"800-5521","price":43.11,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0718\/5131\/1286\/files\/57_2c911b90-4dc5-46cd-bc35-2cfa1a0589bb.png?v=1779570785","url":"https:\/\/oakvillemodeltrains.com\/products\/circuitron-5521-bd-1hd-block-occupancy-detector","provider":"Oakville Model Trains Depot","version":"1.0","type":"link"}