BD-1HD Heavy Duty Block Detector Opto-electronic

BD-1HD Heavy Duty Block Detector Opto-electronic

Details:

The CIRCUITRON BD-1 is an advanced integrated circuit block occupancy detector designed to provide reliable, positive indication of train presence anywhere within a protected block section of a model railway layout. Using proven opto-electronic detection technology, it delivers accurate occupancy status without requiring any modification to locomotives or rolling stock.

Two pairs of CIRCUITRON opto-sensors are installed between the sleepers at the entry and exit points of each block. When any rolling stock enters the section, it blocks ambient light reaching the sensors, triggering the BD-1 logic circuitry and activating the appropriate block indication. The system is fully bi-directional, ensuring correct detection even if a train reverses out of a block.

The BD-1 includes built-in driver circuitry capable of operating a pair of two-colour LED signals or incandescent lamps at each end of a protected block. LED signals must be wired in a common anode configuration for correct operation. The standard outputs are rated up to 250mA per channel, providing reliable control for typical model railway signalling installations.

For larger scale applications, the BD-1HD variant offers heavy-duty output transistors capable of driving up to 500mA per output, making it suitable for high-power incandescent signal systems.

The BD-1 requires a 10–18V DC filtered power supply for proper operation. Compatible power options include CIRCUITRON PS-1 or PS-2 units where unfiltered supplies are in use. The module is constructed on a compact 2" x 3" printed circuit board for easy installation.

Features:

• Opto-electronic block detection with no rolling stock modification required
• Bi-directional operation for accurate occupancy indication in all movements
• Integrated signal driver outputs for block signal control

Additional Information:

• Input voltage: 10–18V DC (filtered required)
• Detection method: Dual opto-electronic block occupancy sensing
• Directionality: Fully bi-directional detection
• Output rating: Up to 250mA per output (BD-1 standard)
• High-power variant: BD-1HD up to 500mA per output
• Signal compatibility: LED or incandescent two-colour block signals (common anode LED configuration)

Measurements:

• Length: 76.2 mm
• Width: 50.8 mm