| 摘要 |
<p>A degaussing apparatus for cancelling the magnetic bias of a magnetisable workpiece by applying a decaying sinewave degaussing signal to the workpiece (H) comprises a start switch for initiating the degaussing signal. A microcontroller circuit (20) is in electrical connection with the start switch and has memory and other registers capable of retaining and operating on instructions and data, and is capable of multiplying binary values, having output (P0.1 to P0.7) for sending output signals and inputs (P1.0, P1.2, P3.2) at least one of which (P3.2) is an offset indicating input for receiving input signals, capable of generating on the outputs a series of binary values, the linear plot of which is stair step approximation of a sinewave whose step height is variable in response to the instructions, and capable of centring the series of binary values about an offset value, responsive to a signal received by the offset indicating input.
<??>A digital-to-analog conversion circuit (30) has a digital input connected to the output of the microcontroller circuit (20) and analog outputs, the digital-to-analog conversion circuit in operation translating a digital input signal to a predetermined voltage level output signal. A current amplification circuit (60) increases the absolute value of the output signal of the digital-to-analog conversion circuit to produce the degaussing signal.
<??>An offset detecting circuit (70) has one input connected to ground, a second input connected to receive the degaussing signal and an output connected to the offset indicating input generating an offset indicating signal upon detection of a potential difference between ground and the degaussing signal. </p> |
