Krautkrämer Gmbh & Co.

Horst Pollok

Klaus Volkmann

Manfred Kickartz

An ultrasonic measuring device that is especially suited to nondestructive testing of materials is fitted with an ultrasound test head 72, a transmitter (74) and a receiver (76) that is characterized by a broadband logarithmic amplifier (78). This amplifier consists of several amplifier stages that are identical in construction and connected in series. Each amplification stage is characterized by the fact that it contains two transistorized individual amplifiers, namely a first and a second differential amplifier that are connected to one another and whose transistors (20, 22; 24, 26) are each interconnected at their base and at their collector. Each of these transmitters is connected at the emitters via inverse feedback resistors (34, 36; 40, 42) to a constant-current source (46, 50). At least the constant-current source 46 of one of the two differential amplifiers of an amplification stage is connected on one side to a digital analog transformer (58) that provides corrections for calibrating each connected constant-current source (46).

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Wesseling, Germany

Horst Pollok