DCC-MB Booster

BOOSTER STILL BEING DEVELOPED

The booster converts the TTL (5 volt, low current) output of the logic board into the DCC track signal (+/-13 volts, high current).

Although I have not yet designed my booster, it has been reported that the Serial Port Booster from the DCC working group's web site will work. The Safety Circuit at the bottom is not necessary in this case, as the logic board will always send a stream of bits, even if the computer crashes.

RELAY SWITCHING DIAGRAM

This diagram illustrates how two relays are used for track power switching. The relays are controlled by the software driver, through the parallel port. A short section of track, electrically isolated from the rest of the layout, is used for programming locomotive decoders. In normal operation, this track has full track power along with the rest of the layout. When programming a locomotive decoder, only this track is powered so that other locomotives on the layout will not receive the programming commands.

Relay 1 (DPST normally open contacts) allows the booster's output to be turned on or off. When the software driver mode is "OFF", this relay, and thus all track power, will be switched off. When the driver mode is "OPERATE" or "PROGRAM", this relay is switched on, connecting track power to the layout. IMPORTANT NOTE: Before you load the software driver, this relay might be turned on - therefore you should turn on the booster power after loading the driver.

Relay 2 (DPST normally closed contacts) controls the decoder programming track. When the software driver is in "OPERATE" mode, this relay is de-energized - the contacts are closed - delivering full track power to the entire layout including the programming track. When the software driver is in "PROGRAM" mode, this relay energizes which (a) inserts a resistor in series with the programming track, thus limiting available current (as per RP 9.2.3), and (b) cuts all power to the rest of the layout.

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