9v battery powering the electronics. On the replica, this hatch is fixed shut as the 9v battery is no longer used. 2) The main electronics circuit board is completely different, with surface-mount components and a different processor chip and software. 3) Motor rotation is detected by rotating magnets fitted to the motors, and hall-effect detectors on the circuit board - the original used optical detectors. 4) The original used an incandescent light bulb; the replica uses an LED. 5) The original used 4 x 'D' cell batteries and a 9v PP3 battery; the replica just uses 3 x 'D' cells. Since the initial release of the replica, a second version has been introduced, the differences being in the test program and the power switch. Version 1 has a single-position power switch, either on or off, whereas version 2 has a 3-position power switch, centre off, forward for use on carpets, back for use on smooth floors. This affects the stall-detection in the electronics, as the original version seems to have been designed to run on smooth floors, and easily stalls when attempting to turn on carpet. The test program for version 1 runs the unit forwards, pauses, then runs backwards; in version 2, the model runs forward, then turns 180 degrees, runs forward again, then backs up a little. The Bigtrak Rover A new model, the Bigtrak Rover, is scheduled for release by Zeon Ltd in late 2014. This model is based on the Junior chassis. "Robotics go back to the future with the retro looks of smash-hit 80s toy Bigtrak working together with high-tech smartphone technology. Now you can have your very own mini Bigtrak robot controlled by your smart device. Rover's on-board camera streams live video from his field of view, directly to your computer, tablet or phone. Bigtrak Rover uses contactless technology to go exploring. He will go forwards, backwards and spin both clockwise and anti-clockwise. Cones are included for orienteering fun. Bigtrak Rover can be controlled by simply downloading a free App from the App Store or Android Marketplace and then follows commands from your iPhone, Android device, PC, Mac or tablet. Bigtrak Rover does not draw any power from your smartphone, and does not require Bluetooth or Wi-Fi connectivity." The Bigtrak XTR The Bigtrak XTR was intended for release in 2012 but has not yet launched . It is an updated version of Bigtrak, its