Gwire to 5A DCC modifications

The following instructions show how to convert a GWire receiver to an Airwire Compatible 5A Battery powered DCC driver. This essentially lets you have the equivalent of a CONVRTR 60 for about half the cost. Well, not quite, you still need a source of 5V DC (Pololu has them). This setup is also compatible with my Protothrottle to Airwire Interface.

Above is the standard gwire receiver. These are not being made anymore (to my knowledge) but they are available on Ebay and from other retailers. By connecting the power and rx lines, you can directly drive a large scale DCC decoder using our DCC amplifier. The amplifier is rated at 5A, so you can power the Soundtraxx TSU-4400 or the TCS Wow 501 series of decoders using your Airwire T5000 transmitter and battery power.

Here are the parts required. Not much, just two wires for power (the receiver needs 5v DC) and half of a servo cable to connect to the DCC Amplifier. The cable shown is a home made servo cable, you can get parts to make your own at Pololu.com or just cut an already made one in half. The component on the left attached to the red/black wires is simply an odd shaped power connector. For testing I use a ‘wall wart’ 5v power supply, this connector fits the ‘barrel’ sort of plug on the 5v wall wart. When installed in a locomotive, I use a tiny ‘step down’ switching power supply.

This shows the basic soldering effort, it’s quite simple. Gang the (red) power wires to the receiver and the servo connector, then do the same to the ground (black) wires. Solder the white wire to one of the RX tabs. Either one will work, the full DCC signal is on both. What we are doing is providing power to the gwire board and the logic chip on the Amplifier board. The white wire is then the signal that carries the logic level DCC output of the receiver over to the Amplifier. The Amplifier boosts the logic level (5v) DCC signal up to 14-28 volts (depending on what battery power you provide) and sends that to the DCC decoder.

Completed soldering job.

Testing. Here I have it hooked up to a small Economi (soundtraxx) 2A decoder. The clips are to examine the dcc signal to make sure it looks good and is clean. The data stream is coming out of the Protothrottle Translator board.

Above is a trace from the logic analyzer showing what is going in from the transmitter and what is coming out feeding into the DCC amplifier. They are skewed ever so slightly, it does take a couple of micro seconds to go out over the air and be decoded at the destination. Top trace is going out, next down is coming in, bottom one is another receiver at the same address (003 in this case) and the decoded message packets (with the blue squares) at the bottom. (also displayed in the right side box)

Here are the two components hooked up. Note that the signal/power wire to the DCC amplifier can be quite long if needed, I’ve just used a short one here since I am just testing with this one.

This shows the basic connections. The power switch, fuse and charging jack are not show above. The figure below shows these in more detail

Here is a more detailed hook up diagram that shows a fuse, the power switch, a charging jack and the basic connections. Note that this is generic to all receivers, bluetooth, gwire and the Xbee boards. The jumper/connectors (j 1 and 2) can be eliminated, I generally do not use them, I just wire everything directly.

I got everything hooked up and took a quick video.