• Circuitron Block Occupancy Detector




    The CIRCUITRON BD-1 is an advanced,

    integrated circuit design Block Occupancy

    Detector utilizing our proven Opto-Electronic

    design which provides

    positive indication whenever

    a block-section of a

    layout is occupied by

    any piece of rolling

    stock. Two pair of


    Sensors (included) are

    mounted between the

    ties at the end points of

    the block that is to be

    protected. Any piece of

    rolling stock entering the

    block shades the Opto-Sensors from ambient

    room light which activates the logic circuitry

    on the BD-1 circuit board. No modifications to

    rolling stock are necessary. The BD-1 is bidirectional

    and will give proper indications even

    if a train leaves a block by reversing direction

    and backing out. The CIRCUITRON BD-1 also

    contains driver circuitry sufficient to power a

    pair of two-color LED (including 2 lead Bi-Color

    LEDs) or incandescent lamp block signals at

    each end of the protected block (LED-type

    signals must be wired with a common anode

    [+] configuration). The outputs on the BD-1

    can control a maximum of 250 ma. For 3-

    color signaling, additional signal drivers will be

    necessary (see our SD-x series of drivers later

    in this section). The BD-1 requires a 10-18

    volt DC input for proper operation. The power

    supply should be filtered for proper operation.

    If you do not have a filtered power supply, the

    CIRCUITRON PS-1 filtered AC to DC Converter

    or PS-2 Regulated AC to DC Converter are

    ideal for this application. The BD-1 is

    constructed on a 2” x 3” printed circuit board.

    The BD-1HD is identical to the BD-1 but

    includes heavy duty output transistors to

    power lamps in large scale signals. Each

    output on the BD-1HD can control 500 ma.