Security circuit for fruit machine - uses logic gates to determine whether stop signal coincides with actual stopping of rotating wheels

摘要

An electronic circuit monitors each wheel of the machine and ensures that the stop signal coincides with the actual stopping of the wheels. The rotating wheel generates pulses via a proximity switch. These pulses are integrated by a monostable resulting in a continuous signal whilst the wheel is moving. This signal, together with the stop signal derived from a switch is fed to an AND-gate. Coincidence of the stop signal and the actual stopping of the wheel sets a timing device. The output of this, together with that of similar devices linked with the other two wheels is ANDed and results in a signal which initiates payment. Additionally, an exclusive OR-gate may be employed to determine whether rotation continues after the stop signal.