Transport trolley control system - has transmitter and a receiver on each trolley with signal amplitude detector including three variable gain amplifier stages

摘要

The control system for each trolley has a transmitter and receiver. The transmitter has a constant frequency oscillator (10) such as a quartz oscillator operating at a frequency of 100Hz. The signal is amplified in the power amplifier (12) and transmitted through the aerial (14), consisting of a coil (16) and a condenser (18). The receiver has an aerial connected to the primary side of a transformer and hence to an amplifier, a mixer and a band filter. This is followed by a comparator and decoder.