| 摘要 |
An electronic device drive circuit has a power supply 1 with mains terminals 11, 12, a first rectifier CR2 feeding a positive rail 5 and a second rectifier CR18 feeding a negative rail 4. A controller uses an inductor L2 to drive negative current from the mains onto the positive rail. The controller is arranged to cause negative current to flow through the inductor from the negative rail when additional power is required for activities such as RF transmission. The controller may comprise control switches QP19a, QP19b arranged to receive a square wave for starting and stopping negative current flow. The electronic device may be an alarm device such as a smoke, heat fire or carbon monoxide alarm. The controller may be adapted to not drive said negative current during device standby, and cause said negative current if the device is in alarm mode and/or communicating with a radiation transmitter. |
