Sennheiser Electronic Gmbh & Co Kg

Frank Hagemeyer

Stefan Thien

Stephan Scherthan

Peter Himmelreich

The invention relates to a DC to DC converter comprising a DC to DC converter unit (DCW), a first field effect transistor (FET) for the voltage conversion, a bipolar transistor (BP) as a starting aid, and a second field effect transistor (FET) for switching-off the bipolar transistor (BP). Said bipolar transistor (BP) is mounted in parallel with the first field effect transistor (FET), and the second field effect transistor (FET) is mounted upstream of the bipolar transistor (BP).

DC to DC converter

A wireless receiver for receiving a wireless transmitted audio signal from a wireless transmitter is provided. The wireless receiver comprises a tuning assisting unit for assisting in the tuning of a music instrument coupled to the wireless transmitter. The tuning assisting unit indicates whether the audio signal from the music instrument corresponds to a specified frequency. The wireless receiver furthermore comprises an audio amplifier for amplifying the received audio signal. The wireless receiver furthermore comprises a housing which incorporates the tuning assisting unit and the audio amplifier.

Wireless receiver

There is provided an FM demodulator comprising a transistor (Q), a filter unit for producing first and second amplitude-modulated signals from a received frequency-modulated signal, wherein the filter unit is coupled to the switching transistor (Q), and first and second diodes (D) connected in opposite relationship for rectifying the first and second amplitude-modulated signals of the filter unit. The filter unit has an LC network and is so dimensioned that there is a linear relationship between the output voltage and the input frequency. The demodulator further has an operating point adjusting unit for adjusting an operating point of the transistor. The operating point adjusting unit () is adapted to effect operating point adjustment with a noise negative feedback.

FM demodulator

A low-noise oscillator circuit with an amplifier element for negative feedback, specifically a transistor. In addition to a positive feedback of the oscillator transistor, provision is made for a negative-feedback loop with a pass band of 0 (thus DC coupling) to 1/4 to 1/100 of the oscillation frequency of the oscillator, in order to regulate out fluctuations of the current of the amplifier element.

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Wedemark, Germany

Frank Hagemeyer