| 摘要 |
<p>A DC motor (1) is connected in series with a power transistor (2). An adjustable potentiometer (3), whose tapping determines the base voltage of the power transistor (2), is used to vary the speed of the DC motor (1). In order to protect the power transistor (2) in the event of blocking of the DC motor (1), a comparator (8) is provided with compares the current through the motor (1) with a reference value and controls a relay (9, 10) in such a manner that the power transistor (2) is short-circuited if the current through the DC motor (1) is higher than the reference value. <IMAGE></p> |
