Television tuning system indicator

Abstract

An all channel television varactor diode tuning system has a presettable counter for deriving the number of the receivable television channel by counting pulses indicative of the tuner local oscillator frequency, which is varied by a voltage ramp circuit under the control of a comparator. The derived channel number is supplied to one input of the comparator, and a channel number selector supplies an encoded desired two digit channel number to the other comparator input and to a frequency band decoder. The band decoder supplies signals to establish appropriate preset counts for the counter in accordance with the frequency band. The channel number selector includes a keyboard coupled to a multi-location tens and units memory for encoding and storing desired channel numbers. The keyboard is also coupled to a function/number decoder which distinguishes between digits and controls the state of a flip/flop in decoder circuitry which subsequently controls a units and tens position display device. The flip/flop, through logic circuitry, enables display of a first digit entered at the keyboard in the tens display position while blanking the units position and enables both display positions only for completed two digit channel number entries.