| 摘要 |
<p>PURPOSE:To obtain a current supplying circuit which has no power consumption and also has feeding characteristics equivalent to those of a latter coil, by connecting a power source to the primary winding of a three winding transformer and providing the three winding transformer with a switching element which intermits a current flowing to the primary winding. CONSTITUTION:A transistor (TR) 218 and the 1st and the 2nd diodes 207 and 209 constitute complementary switches; when the TR218 is on, the energizing inductance of the transformer 205 is charged with energy by a current from a battery 200 and when off, the energy is supplied to the telephone circuit connected between terminals 202 and 206 and to one input of an adding circuit 214. At this time, capacitors 208 and 210 smooths an output voltage together with the energizing inductance of the transformer 205. A comparator 216 and a control circuit 217 perform intermittence control over the TR218 so that the output of the adding circuit 214 is equal to the electromotive force of a reference voltage source 215.</p> |
