Abstract: The present invention relates to a circuit arrangement which comprises at least one 3-level pulse width modulation inverter with a snubber circuit. The snubber circuit is formed by at least one coil (L), two capacitors (Cu, Co) and a series connection comprising four diodes (Dh1-Dh4) poled in the same direction, whereof the two outer diodes (Dh1, Dh4) are in each case directly connected to the input terminals (1, 3) for the positive and the negative pole of the input voltage. The electrical connection between the two inner diodes (Dh2, Dh3) is connected on the one hand via the coil (L) to the input terminal (2) for the center tap of the input voltage and on the other hand to the middle bridge branch of the pulse width modulation inverter. In one embodiment, the two capacitors (Cu, Co) are in each case connected with one terminal to the electrical connection between one of the inner diodes (Dh2, Dh3) and one of the outer diodes (Dh1, Dh4) and with the other terminal directly to the output terminal (4).

Abstract: The present invention relates to a circuit arrangement which comprises at least one 3-level pulse width modulation inverter with a snubber circuit. The snubber circuit is formed by at least one coil (L), two capacitors (Cu, Co) and a series connection comprising four diodes (Dh1-Dh4) poled in the same direction, whereof the two outer diodes (Dh1, Dh4) are in each case directly connected to the input terminals (1, 3) for the positive and the negative pole of the input voltage. The electrical connection between the two inner diodes (Dh2, Dh3) is connected on the one hand via the coil (L) to the input terminal (2) for the centre tap of the input voltage and on the other hand to the middle bridge branch of the pulse width modulation inverter. In one embodiment, the two capacitors (Cu, Co) are in each case connected with one terminal to the electrical connection between one of the inner diodes (Dh2, Dh3) and one of the outer diodes (Dh1, Dh4) and with the other terminal directly to the output terminal (4).

Abstract: Sensor system for regulating machines, especially sewing machines, with a light barrier comprising a light emitter and a light receiver. The light emitter provided is an incandescent lamp supplied from an energy source. An evaluating stage of adjustable sensitivity is connected to the light receiver. The energy source of the incandescent lamp is regulated, and is coupled with the evaluating stage in such a way that the desired value of the regulated energy source is automatically adjustable in dependence on the sensitivity setting of the evaluating stage.