Abstract: In order to improve the large signal handling capability of a logarithmic amplifier comprising amplifier stages successively performing their limiting actions in response to an increase of the input signal, and an adder stage for the output signals of the amplifier stages, the signal of the amplifier stage which is the last to perform its limiting action in response to an increase of the signal is amplified by a value which is higher than that of the signals of the other amplifier stages.

Abstract: Circuit arrangement for linearly amplifying and demodulating an AM-modulated signal, and integrated semiconductor element for said circuit arrangement. A linear amplifier and demodulator for AM-modulated signals comprises a logarithmic amplifier having a number of amplifier stages successively operating in a limiting mode, an antilog circuit, and DC separation between the logarithmic amplifier and the antilog circuit.

Abstract: An FM-receiver having an FM-channel successively comprising an RF-input stage and mixer stage (B), an IF-circuit (A) and a ratio detector (R). The ratio detector incorporates silicon detector diodes and a smoothing capacitor conductively connected to the detector diodes for a dynamic amplitude limitation of the ratio detector output signal in dependence on the amplitude of the ratio detector input signal. A bias voltage is applied to the silicon diodes to prevent the silicon diodes from being blocked at signals lower than the threshold voltage of the diodes. The bias voltage comprises an average noise voltage that is generated by amplifying a noise component of the FM signal, the noise component being present in the IF bandwidth. The average noise voltage is predominantly obtained by amplifying the noise produced within the IF-passband of the IF-input stage.

Abstract: FM-receiver comprising a search tuning arrangement, a control device for making the search tuning arrangement operative, a frequency discriminator and a stop-pulse generator having a threshold and being connected to an output of the frequency discriminator and supplying, when its threshold voltage is passed by the output voltage of the frequency discriminator, a stop-pulse for rendering the search tuning arrangement inoperative, the demodulation sensitivity of the frequency discriminator being brought from a maximum to a minimum level in order to prevent false stop-pulses from being generated in response to the fact the threshold voltage is exceeded by detected audio signals and said detection sensitivity being brought from the minimum to the maximum level when the search tuning arrangement is made operative, in order to enable tuning to weak and/or adjacent transmitters during the search tuning process.

Abstract: By using a optical switch, which can be operated by the tuning knob of a receiver, signals can be obtained which accurately correspond to the operation of the tuning knob for switch-over of the receiver to a continuous manual tuning mode and for suppressing the automatic tuning correction during tuning.

Abstract: By using a double potentiometer one of which is used for tuning and the other for adjusting a level whose variation suppresses an automatic tuning correction, a great freedom can be obtained in designing the tuning section of a receiver with automatic tuning correction suppression.

Abstract: A receiver tuning circuit in which without operation of extra switches a change-over can be made from tuning by means of a continuously varying tuning voltage to tuning by means of one of a number of adjusted tuning voltages by using a capacitor controlled by an automatic tuning correction current source circuit for obtaining said voltage, and an automatic switch for applying the desired tuning voltages to this capacitor.

Abstract: A station finder which switches to automatic frequency control during automatic finding in case of reception of a transmitter and, if desired, continues to find a transmitter some time later with the frequency control switched off.

Abstract: A tuning circuit in which when the field strength of a received signal drops out, a tuning voltage from a switch can be applied to a capacitor so that the circuit stays tuned to the received signal. The voltage at the capacitor can further be controlled from a finding signal generator so that a station finding action which is independent of the inertia of the servo control can take place.

Abstract: Integrated circuit for superposition of an AFC control voltage on a stabilized direct voltage for varactor diode tuning in radio or television receivers. It features a voltage divider having a controlled current applied to it. A circuit disables it when tuning.