Tachometer measuring velocity of ball struck by sportsman - has acoustic sensor at start point and net tension detector at finish point to control calculator

摘要

The numerical tachometer indicates average velocity of ball struck or thrown by a sportsman. This is performed by sensors at start and finish points of trajectory. An acoustic sensor (1) is located near the point where the ball starts moving. Noise is amplified and wave shaped to control a relay (16) to start counter in a calculator (3). The distance (D) from arrival point is programmed into the calculator. A second sensor comprises a net (4) between two posts (5, 6) to which intermediate posts are connected by cables (12, 13). These are attached to the posts by sensors measuring tension variations. Elongation of the net controls the relay to stop the counter. The calculator then determined the ball velocity.