MODEL RAILROAD PRINTED CIRCUIT BOARDS
MRR PCB
5138 Atchinson Drive SE
Olympia, WA 98513-4529
Phone: (360)456-0572
Model Railroad Printed Circuit Boards
BCD-7 ELECTRONIC STAGING YARD CONTROLLER PRINTED CIRCUIT BOARD
The BCD-7 Card:
The MRR PCB BCD-7 Printed Circuit Board:
This BCD-7 Card is an Electronic Staging Yard Controller (ESYC) devise that helps manage Staging Yards, Sidings and Hidden Yards. You can select up to seven (7) Staging Tracks from one Throat in and/or one Throat out.
1. These are some of the reasons to use an ESYC: Selecting a track can be complicated and confusing.
2. Un realistic Model Railroading
3. Switching of track Power on off. Whether you use Cab Control (DC) or Command Control (DCC), all track power should be turned switched off except the one in actual use. This will prevent someone selecting a wrong siding or wrong channel, causing a staged train to start moving accidentally. Also you probably don’t want your engine sitting for hours at a time with their receivers or decoders powered up with their headlights on.
4. Simplified track diagrams with no track power toggle switches and no turnout toggle switch for track alignment.

The ESYC is an electronic devise using a Binary Code Device (BCD) rotary selector switch interfaced with a BCD Intergraded Circuit (IC), which is connected to an IC driver to power lights, diodes or relays. The PCB also contains a voltage regulator to provide 5 Vdc for the operation voltage for the BCD Intergraded Circuit (IC).

IC’s used:
1. CD4028 (BCD to Decimal Decoder)
2. DS2003 (High Current/Voltage Darlington Driver)
3. LM7805 (5 Volt dc Voltage Regulator)
For track alignment you can use the MRR PCB M-10-10 Diode Matrix Card and MRR PCB R-4-2 Relay Card.
For track power you can use the MRR PCB R-4-2 Relay Card.

We are using the Molex 0.156" on all our Printed Circuit Board connectors for the input, output, and power connections. These connectors are sturdy, reliable, and easily available to the hobbyist. We use connectors rather than direct soldered wire connections in order to make it easier to repair or replace a failed unit, but you can solder the wires directly to the board as well if you prefer.


© Jerry F. Barnes… 19 January 1997
Under Construction
Under Construction
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Started Counting: 21 February 2003
Last Date Revised: 21 February 2003
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