Abstract: A two-terminal switch circuit (1) for periodically energizing a load (20) from a voltage supply includes a controllable switch (4) connected between the switch terminals (2,3), a resistance (8) and a capacitor (9) connected in series between the terminals (2,3), and a voltage threshold responsive arrangement (26) having a hysterisis characteristic. The voltage threshold responsive arrangement has a signal input (27) and a power supply input (29) connected to the common point (12) of the resistance and the capacitor, and a signal output (28) connected to a control input (13) of the controllable switch. The voltage threshold responsive arrangement is powered by the capacitor voltage. The threshold responsive arrangement closes the switch when the capacitor charges to a first threshold voltage and opens the switch when the capacitor thereafter discharges to a second threshold voltage which is lower than the first threshold voltage.

Abstract: A two-terminal switch circuit (1) for inclusion in series with a load (20) across a voltage supply (63) for periodically energizing the load (20) from the supply (63) comprises a controllable switch (4) connected between the terminals (2,3), a resistance (8) and a capacitor (9) connected in series between the terminals (2,3), and a voltage threshold responsive arrangement (26) the output signal/input signal characteristic of which exhibits hysteresis. The voltage threshold responsive arrangement (26) has a signal input (27) connected to the common point (12) of the resistance (8) and the capacitor (9), and a signal output (28) connected to a control input (13) of the controllable switch (4). A power supply input (29) of the voltage threshold responsive arrangement (26) is also connected to the common point (12) of the resistance (8) and the capacitor (9) so that the voltage threshold responsive arrangement (26) is powered from across the capacitor (9).

Abstract: A deflection circuit includes a deflection correction circuit (Vs) with a controllable active voltage source (Vs) arranged in a loop formed by a deflection coil (Ld), an S-capacitor (Cs), and a flyback capacitor (Cf). The voltage source (Vs) receives a further power supply voltage (Vb2) and a modulating signal (M) to supply a modulating voltage (Vm) varying in response to the modulating signal (M). The active voltage source (Vs) includes a switching element (S2) which is switched on and off with a frequency which is substantially higher than the deflection frequency to to enable waveforms of the modulating voltage (Vm) with a frequency content which is substantially higher than the deflection frequency such that any desired waveform can be generated within the deflection period (Td).