| 摘要 |
<p>The system is significantly more economic than prior art is extremely sensitive and does not require forceful insertion likely to sound the alarm. The voltage is produced from an arrangement comprising a voltage U1 relating to key resistance and two fixed voltages U2 and U3 and is obtained when the condition U2U1U3 is satisfied. The insertion of a random resistance in the socket provokes a current in resistor (R1), which, with the key, forms the dividing bridge. The bridge produces a voltage actuating the alarm using the unlocking of a transistor. The emitter and the base of the transistor are connected to the terminals of the resistor (R1).</p> |
