Abstract: In a frequency synthesizing circuit the deviation of the frequency of an oscillator signal which is transmitted (at 7) by a measuring gate (79) from a desired frequency (output 47) is converted into a control signal (at 3) for the oscillator (11). In order to prevent the occurrence of an average frequency-deviation due to a continuous change of the phase relationship between a test pulse (m) controlling the measuring gate (79) and the oscillator signal, an additional pulse (output 83 or 85) is added (via 81) to the output signal of the measuring gate (79). This additional pulse must occur contiguous to the test pulse. (FIG. 1).

Abstract: A frequency synthesizer tuning circuit oscillator having an output signal frequency controlled by an input control signal is compared with the frequency specified by a source of data. The digital difference between the two compared frequencies comprises a multi-bit digital error signal of most and least significant bits. An error control signal for applying to the oscillator control input is derived by modulating the average pulse duration of a periodic pulse signal with the most significant bits of the digital error signal when the digital error signal is greater than a minimum frequency. The periodic pulse signal is amplitude modulated with the least significant bits of the digital error signal when the digital error is less than a maximum frequency. Both amplitude and pulse duration modulation of the periodic pulse signal occurs with the most and least significant bits of the digital frequency error signal when the frequency difference is between the maximum and minimum frequencies.

Abstract: A switching circuit in which one out of a plurality of input channels is connectable to an output channel via one of the switching devices in the circuit. Each of the switching devices comprises an emitter-coupled pair of transistors which have a switchable current source in the emitter lead, the base of the first and the second transistor, respectively, of each pair being connected to one of the inputs and to the output, respectively. The output channel of the circuit comprises a transistor the emitter of which is connected to the output and the base to the interconnected collectors of the second transistors, this junction point being connected to a voltage-carrying terminal via a resistor. Via a selection switch which is connected to the switchable current sources only one of the input channels can at all times be connected through to the output channel.

Abstract: A video clamping circuit comprising a differential amplifier the output of which is connected to the circuit output via a diode and is also fed-back to an amplifier input which is further connected to a reference voltage-carrying terminal via a resistor, the amplifier output being also connected to a capacitor charging circuit for charging a capacitor which is connected to the amplifier input for receiving a video signal. During charging of the capacitor the cut-off diode effects an effective signal separation between the input of the circuit and the output, it being ensured that last-mentioned output carries the constant reference voltage.

Abstract: A television camera features an oscillator signal which modulates the video signal to eliminate microphonics. The signal is applied to the cathode to reduce the required power. It can be a multiple of the line frequency to simplify frequency generation.

Abstract: A television camera having a diaphragm control and a controlled picture signal amplification circuit for keeping a picture signal value substantially constant. A single control system is formed by having the diaphragm opening adjusting element perform the gain control through an electronic control circuit, which takes place at low scene light intensities only. In the automatic control the amplified picture signal is utilized directly for the diaphragm control and, at low light intensities, indirectly for the gain control. With manual control the operator directly influences the diaphragm adjusting element and, consequently, indirectly the gain control at low light intensities. In the automatic control no discontinuities occur in the control characteristic and with manual control operation is simplified.