| 摘要 |
A magnetic drill (10) is provided with an alternate power source (36). The drill (10) comprises: an electric motor (32) for driving a tool; a controller (33) configured to receive an AC input signal and operable to control a drive signal to the electric motor (32); an electromagnet (28) arranged in a base (24) of the drill housing and operable, in response to a DC voltage, to magnetically couple the base to a surface proximate to the base (24); an AC/DC converter (34) configured to receive the AC input signal and operates, independent from the controller (33) and in the presence of the AC input signal, to output a DC voltage to the electromagnet (28); and an alternate power source circuit that monitors the DC voltage output by the converter (34) and, in the absence thereof, provides an alternate DC voltage to the electromagnet (28). |
