Circuitron Block Occupancy Detector
BD-1HD BLOCK OCCUPANCY
DETECTOR - OPTO-ELECTRONIC
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
CIRCUITRON Opto-
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.
