Simple and practical circuit diagram of an elevator failure alarm

  
As we all know, if the elevator power suddenly fails, the distance distribution room duty officer is not immediately found, this time, the crew was on the elevator might panic.
Simple and practical circuit diagram of an elevator failure alarm - schematic

Here are a sound alarm circuit, as shown below, as long as the elevator of a power failure, the elevator distribution room will issue a sound alarm signal. The circuit works as follows: a circuit powered by a 6V battery, AC power once the elevator failure, the circuit that is audible alarm, the alarm time can be set in advance. Alarm to a certain time, the end of the alarm sound, the duty officer to find fault immediately. Once troubleshooting, power restoration work, reported glanced circuit is cut off, while the battery will power the AC voltage charging. On 230V AC power by the step-down transformer X1 battery charging diodes D1, D2 rectified after Manifold IC4 (LM7806) regulator, the battery via a diode D5 and RLI relay normally closed contact (N/C) for charging. When the battery is charging, transistor T1 through the diode D4 is turned, causing the tube T2 is turned off, no current flows through the relay RL1 because without work, the result has been in a state of charge of the battery. The maximum value of the charging voltage of 6V plus D5 pressure drop. Once an AC power failure (eg open circuit), the transistor T1 off, T2 is turned on, the relay pull a job, the normally closed (N/C) contact opens make contact (N/0) is turned on, the rechargeable battery loop is cut off. At the same time, the timer IC2 and IC3 through the relay RLI closed contact (N/0) with battery-on operation. Timer IC3 (NE555) (3) feet of the output pulse signal 1KH2 deactivated IC2 (NE555) reset terminal (4) feet, IC2 works in pulsed mode, (3) an output signal pin of IC2 via the audio amplifier IC5 amplification, push speaker sound an alarm, indicating that the AC broke down.




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