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Air Horns

There are two kinds of air horns. Those that toot, and those that don't. - Image 14 - Air Horns for Show These don't toot. But they do look nice. These came from Precision Steel Car Company of Hamilton, Ohio. They are investment castings. It is true that F7s did not come with Nathan 3 chimes. But it was also true back in the steam days that an engineer could install any whistle or bell he wanted as long as it met the letter of the law. I don't know how far into the diesel days that carried. - Image 15 - Air Horns that Blow These horns DO toot - and in a very big way. They are both installed facing forward behind the radiator grilles, one on each side. They are connected by an air hose to the compressor. These trumpets as purchased are bright red. That would look very bad from the outside so I toned them down by painting them black. - Image 16 - Relay Box Location The compressor mounted to the relay box and the air hose is connected. Notice my custom patented anti-noise coupling compressor mount. It's made from a piece of scrap aluminum left over from a roof or hatch cutout.

Motor Driver

- Image 17 - The main traction motor driver board This is the board that powers the two traction motors. It is not the actual "controller". That is on a separate FPGA board. This board has ten Field Effect Transistors or FETs - also called "switches". Four are rated at 150 volts and drive the motors directly. Four are rated at 80 volts and are used to double the 60 volts from the batteries to 120 volts. One FET bypasses the bridge rectifier during dynamic braking and the other charges the doubler capacitors. Notice that there are NO relays. The forward/reverse function and the two stage transition are implemented using transistors instead of relays. - Image 18 - The main traction motor drive chassis Inside the power drive chassis is the board shown above, four large capacitors, a fast recovery bridge rectifier and a relay. The relay turns on the battery 24 volts to the circuit board in the presence of the battery 60 volts. The capacitors are used by the voltage doubler circuit. They are alternately charged from the battery 60 volts and then added to it, yielding 120 volts. - Image 19 - The main traction motor drive chassis - top Shown are three heat sinks and a fan. The motor drive transistors, the doubler transistors, and the bridge recifier each have a heat sink. The fan is needed because at full output, losses are up to 150 watts, which converts to heat. The Box is 100% recycled aluminum. It is made from hatch cutouts from the locomotive roof which would otherwise be discarded.

Battery Charger

My locomotive needs 60 volts. That's five 12-volt batteries. So how do you charge that many batteries at the same time? It isn't easy. First I tried a scheme to put them all in parallel, allowing me to use a standard 12 volt charger but ran into too many problems. Then I came up with the "Multi- Charger"... - Image 20 - The Multi-Charger This unit sits on the floor of the locomotive next to the batteries. It can be started and shut down remotely. A five inch fan is mounted inside the charger box and is needed to cool the tranformers and rectifiers. The adjusting shaft that protrudes from the side sets the final charge voltage. The Box is 100% recycled aluminum. It is made from hatch cutouts from the locomotive roof which would otherwise be discarded. Image 21 - Inside the Multi-Charger This is basically five independent battery chargers all in the same box. Each battery can charge at a rate determined by it's own state of charge. A relay circuit shuts down the whole box when the total of all batteries reaches a set voltage preventing over charging.

The Handheld Radio Control Box

- Image 22 - Handheld Radio This is a wireless handheld control box. Functions match the wired version shown below. It uses a Zigbee radio and is networked to a receiver inside the locomotive's steam hatch. Both the handheld and locomotive based endpoints are now fully operational. I must hold the unit as shown in order to power it up. That is a safety feature. If I fail to hold the unit properly, the locomotive will go into dynamic braking.

The Wired Handheld Control Box

- Image 23 - Handheld Wired Controller The handheld controller is simple - nine switches in a box with a connector. Most switches are simple on-off toggles for things like train line, number boards, service lights, and classification lights. It serves an alternative to the radio link for controlling the locomotive. The headlight switch is a double throw center off. The "up" position lights both head lamps. The "down" position lights them alternately. The throttle/brake control switches are double throw center off, but are also momentary. They are used to increase or decrease throttle or brake settings. The horn and bell use the same circuit. The bell switch connects it to +12 volts. The horn button connects it to ground. - Image 24 - The "B" End The handheld controller attaches to the locomotive via this connector mounted just above the rear coupler. Eventually I plan to make this wireless. Not today. - Image 25 - Connector Close Up And a close-up of the connector and the wiring bundle. (Couplers are from Tom Bee.)

The Relay Box

- Image 26 - Relay Box The Relay Box contains the main relay, horn relay, and a hand wired circuit board which controls the horn, bell, and head lights. There are numerous connectors which attach to various wiring harnessed within the locomotive. The bell and horn compressor are attached to the outside of the relay box. The compressor is mounted with a special spring that was designed to support the compressor without transmitting the sound from it to the chassis. - Image 27 - Inside the Relay Box Here's a view inside the relay box showing the components I described above. You can view Schematic Diagrams for everything on this page by following the link. Here are schematics and such for the Radio Control interface. Page 3