| 摘要 |
<p>Problem: To provide a simple and low cost off-mains device to switch off the mains voltage to an electrical apparatus when this is not used, partly in order that the apparatus is not left energized with mains voltage, partly to avoid electrical and magnetic fields, and partly to save power. Solution: the off-mains device comprises a relay in the connection to the mains and an auxiliary voltage source in the form of a capacity capacitor for activating the relay such that the relay switches on the mains to the apparatus when the apparatus is activated, and switches off the connection to the mains when the activation of the apparatus ceases. An oscillator and a resonance circuit cooperating with it keep the capacity capacitor charged, said oscillator being connected to the mains via a voltage supply with rectification and voltage limiting means.</p> |
