A DCC BOOSTER FOR DCC-MB AND TNT

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Here is the schematic developed by Chuck Heller. I have redone the artwork so that it is more legible. You should print a copy of it for your three ring binder, and another copy for you to use at your workbench for when you are assembling and soldering the circuits. I print it in landscape view so it is as large as possible on a 8-1/2 x 11 paper.

NOTE: I have changed the numbering of the resistors from Chucks hand drawn schematic. The numbering of the resistors on my drawing includes the pull up resistors in the logic portion of the schematic, this resulted in the need to renumber some resistors in the booster section to accomodate the added numbers. This will be consistent with my parts list. But be aware of the difference between my drawing and Chuck's, available on the Tillorp's site. The parts list is prepared from my redrawn schematics.

This schematic shows the Booster(Booster portion). In my construction of this system I have the logic portion on the logic card, and the booster is in the booster cabinet. My booster cabinet also contains the wiring to get the Joystick port into my throttles. My Command station (logic portion) is separate from the booster and is connected by 5 pin DIN cable. My booster cabinet also contains a simple 5 volt regulated supply to power the logic portion of the circuit. The 5 pin DIN carries the two logic wires, 5VDC, and ground connections.

You can right click on either of the pictures of the schematic and save it as BOOSTER_SCHEM.JPG or BOOSTER_TNT.JPG into your TNT folder or your pictures folder, or any other folder you like, so long as you remember where you put it.



R19 at location marked A is used when you wish to implement an acknowledge circuit, otherwise it can be omitted and this line connected directly to ground. This is discussed on Teton Short Line's website, and also Tillorp's website. I don't use it, but I may. Right now I rely on the decoder acknowledging reception of programming information by jolting the loco motor.

Also, this circuit does not provide for relay control of track power during programming or when software has turned off system. TNT provides notices as to when this will happen. I have equipped my layout with a DPDT switch to remove the main line layout from track power when I want to program a decoder. To program a loco decoder it should be isolated from other decoders on the layout to prevent reprogramming of all the decoders. Usually a separated programming track is used for this. The programming track is isolated from the mainline with insulated track joiners, and then a switch is provided to remove power from mainline, when relays are not used.

I think you will agree this is a very simple circuit, with few components, and easily wired without printed circuit boards.

Here's the booster schematic again in parts layout format. This schematic includes the LM 338 adjustable voltage regulator and the 5 volt 7805 regulator for the Command station logic card. The adjustable voltage regulator can be adjusted with the 20 turn Vadj potentiometer to provide 12 to 14 VDC. This will make this booster useful for N or HO model railroads. The 5 Volt regulator should provide a stable 5 VDC in either case.

This picture is of the same circuit as above, but turned 90 degrees clockwise.


A very special Thank You goes out to Mr. Ron Pringle who has pointed out an error I made in the parts layout drawing above, which is now corrected. Good work, Ron! Thank you for your valuable input and fine work.

Ron has built the system using Micheal Brandt's original logic card design and interfacing it to this booster using a dual NAND buffer driver to derive the Q and /Q signals.



Here you can see the booster as it is in the cabinet. I use the cabinet to breakout the joystick paddles also. On the back you can see a heat sink I am using for the LM338. This is probly way too large for what is required, but I had it, so I used it. You can see the joystick paddle plugs going into the front, the game port connected to the back left, and the 5 pin DIN connector that goes to the command station card on the upper right.