Abstract: Switching system for transmitting program or data signals from an exchange to a number of subscriber posts, in which the processing of selection signals received by the exchange from the subscriber posts, the tuning of oscillators in the exchange, and the eventual correction of a drifting oscillator are carried out in separate control loops. In a first control loop, the subscriber posts are scanned for selection signals at a high scanning rate. In a second control loop, oscillators which must be tuned to a frequency corresponding to a received selection signal, are scanned and properly tuned within a scanning period. In a third control loop, all oscillators are scanned sequentially and a correction signal is provided if frequency drift has occurred in any oscillator.

Abstract: Electronic switch for switching electrical signals, comprising an input buffer (1) of the open collector type of which the input is connected to the control input (2) of the switch. The output of said input buffer is connected to (1) the input of an output buffer (3) which the output is connected to the signal output (8) of the switch, (2) a diode (4) of which the other electrode is connected to the signal input of the switch and (3) a load resistance (5). Furthermore the other terminal of said load resistance is connected to the signal input of the switch.