Automatic control on the farm should not be confined, to tractors: smaller trucks or trolleys can be run automatically around the farm-yard or buildings, at any predetermined time or on selected routes employing the buried wire or similar system. Doors and gates can be opened and closed automatically with the help of equipment described above, and there are many protective devices that can be fitted to guard the machine in the event of faults in equipment or obstacles in the path of the vehicle.
Automatic control of farming operations lags far behind that of industrial processes and one reason for it is the type of electronic equipment used. Amplifiers and thyratron relays must normally be provided with a high voltage such as main electricity supply, and the thermionic valves are regarded as being too delicate for normal farm usage. The development of transistors has completely changed this outlook. They can be used in place of valves in amplifying and switching equipment, and have many advantages. They are not affected by vibration, so that transistorized equipment can be installed on moving machines.
Another great advantage of transistors is that they can be operated from low-voltage suppliers, such as car or tractor batteries and can, therefore, be used in any remote part of the farm.
Transistorized equipment can also be completely waterproofed and quite safe for use with any outdoor equipment or in dairies and other places where it is not possible to control the splashing of water.