Wireless Speedometer Option

Revised 01-29-08

The Multi-Scale Train Speedometer (MSTS) was originally designed to compute train speed by measuring the time a moving train took to break two infrared light beams spaced 1" apart.


This design works very well and is suitable for many installations. 


It does, however, leave many questions about train speed unanswered, such as "How much does the train slow down as it struggles up a steep grade?" or "Does the train slow down significantly as it goes around a tight curve?"


To deal with these and other similar situations the software and hardware that make up the MSTS have been modified so that an additional microprocessor and a wireless transmitter can be installed in a railroad car that continuously sends out the train's current speed.  By removing the sensor plug from the MSTS a wireless receiver can be installed that will pick up these transmissions and display the train's speed information on the LCD readout.  The system has been tested to a distance of more than 200 feet.
In order for the transmitting unit to have accurate data to compute the train's speed a precisely manufactured optical detector must be installed on one of the car's axles.  This detector sends a stream of 16 pulses to the transmitter each time the car's wheel rotates once. 

To assure accuracy and correct assembly the Wireless MSTS can be purchased with the sensor and transmitter installed in a small gondola.  This car also has ample space for the 9 volt battery that powers the transmitter.  Click here for photos of this installation.

If you would prefer to have the unit installed in one of your cars that option is available. 

Click here to see a sample of the custom sensor installation (Boxcar).

Click here to see a sample of the custom sensor installation (Hopper Car).

As an added bonus the on-board transmitter can also send additional data to the display unit, including battery voltage, current being drawn by the engine and motor or battery temperature.  This information requires a few more modifications to the unit:
  • Voltage
    • if your train operates from battery power you need to power the transmitter and related circuitry from the same battery system that powers the engine.  This can easily be done by routing positive and negative wires from the batteries to the speedometer car and connecting them to the power input on the unit.
    • if the train is operated from track power it is best to power the speedometer from batteries, such as a 9 volt radio battery.  Power from the track needs to run from wheel pickups to a bridge rectifier, assuring consistent positive and negative connections, to the voltage sensing input on the board
  • Current
    • for battery operated engines the power cable to the engine must be rerouted through the sensor unit.  This involves running power from the batteries directly to the sensor unit then to the motor so that the unit can determine how much power is being consumed at any given time
    • track powered trains present additional challenges to measuring current and this option has not yet been implemented
  • Temperature
    • A precisely calibrated temperature sensor can be added to the sensor unit.  This sensor can be mounted directly atop an engines motor or, for battery operated engines, on the battery pack so that its temperature can be monitored.
The same unit can be configured to operate both as a wireless and a wired unit.  To switch between modes hold the MENU button for several seconds when the main copyright screen is displayed.  WIRELESS   NOW=0 or NOW =1 will be displayed.  Continue holding the MENU button until the unit goes to the next screen.  If it was set for wireless (NOW=1) it will switch to wired mode (NOW=0) and visa versa.