| 摘要 |
PURPOSE:To enable the titled cicuit to use an inexpensive miniature relay by providing a B position circuit by the first detection circuit which inputs an A relay drive signal, and a C position circuit which monitors the A relay drive signal by the second detection circuit which changes a comparison voltage by the output of a B position circuit. CONSTITUTION:When a dial pulse is sent out while changing a switch SW OFF ON OFF ON..., the plus input of a comparator CMO falls according to the discharge of a condenser CC2 by a resistor R4 when said SW is turned off, but a transistor Q1 continues to turn on because the turn-off time of switching is short. When the SW is turned on, a condenser CC4 discharges by a resistor R11, but since this switching on time is short, the plus input of a comparator CM1 does not attain to the voltage lower than that of a minus input which is a comparison voltage, thereby a transistor Q2 keeps continuously on-state. Therefore, during the dial pulse is being sending out, a C position circuit is made, which actuates a B position relay and a position relay. |
