Abstract: The invention concerns a method of testing the hardness of workpieces (22), wherein an impact body (20) is moved onto the workpiece (22) to be tested such that it impinges thereon (along a forward path) and rebounds thereof (along a return path). On both the return and the forward paths, a movement value of the impact body (20) is detected by a contactlessly operating device and a measure of the hardness of the workpiece (22) is obtained from the difference between the forward and return path movement values. The movement value is detected at at least two points on the forward path and at at least two points on the return path. Corresponding to each movement value detection point on the forward path is a point on the return path at a substantially similar distance from the point of impact.

Abstract: 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).