MAKING THE COMMAND STATION
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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.

This schematic shows both the Command station(logic portion), and 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 DCCSCHEM.JPG or DCCSCHEMSMALL.JPG into your TNT folder or your pictures folder, or any other folder you like, so long as you remember where you put it.

IMPORTANT NOTE: Each integrated circuit (IC) must be supplied with a 0.1 uF by-pass capacitor. A by-pass capacitor is connected into the IC 5 V supply pin to ground. This is neccessary! During my first circuit construction, I was in a hurry to see if the card would work, and tested the card without these by-pass capacitors. The card did not function. I was dismayed. I noticed it spring to life when I touched the card to check for heat. I installed the by-pass capacitors on each IC between 5Vcc and ground, and all was well. These by-pass capacitors are not shown on the schematic drawings for convenience and to save space, and promote an uncluttered appearance.



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 schematic again in BIG format.