| 摘要 |
1,148,553. Signalling over power lines; generating oscillations. ZELLWEGER Ltd. 7 Feb., 1967 [25 April, 1966], No. 5795/67. Headings H3B and H4R. Signalling over power circuits is achieved by the repetitive connection and disconnection of an oscillatory circuit to the line via electronic switches, the oscillatory circuit being disconnected at a supply voltage peak, connected a half-cycle of the supply voltage later, and disconnected after a further odd number of supply voltage half-cycles. As described the circuit of Fig. 3 is used to generate pulses U s at the peak of each half-cycle of the supply voltage U, the exact phase of the pulses relative the supply voltage being adjusted by the variable resistor 15 in the phase shifting circuit 14, 15. The pulses U s are used to synchronize a monostable multivibrator, Fig. 4 (not shown), so that it triggers in one direction at the supply voltage peak, remains in this state for a half-cycle of the supply voltage, and then remains in the other state for an odd number of half-cycles, e.g. 1, 3, or 5, of the supply voltage. The resulting waveform is applied as triggering voltage U t to the circuit of Fig. 1, to trigger the thyristor 12 so that the thyratron is non-conductive for onehalf-cycle of the supply frequency allowing capacitor 10 to charge up to the peak value of the supply voltage, the thyratron is then triggered and stays triggered for an odd number of half-cycles, so that the resonant circuit formed by capacitor 10 and the primary of transformer 9 is closed through the thyristor 12 and diode 11 so that it resonates and applies the resulting high-frequency oscillations to the power circuit over transformer 9.
|
