CN2267491Y - Device for alarming someone tampering with a lock of door - Google Patents

Abstract

The utility model relates to a door prizing alarm which can send out alarm sound when thieves prize a door. Because a resistor with a high resistance value is serially connected with a static loop of the circuit of the device, the static power consumption is very low and the service life of a dry cell can be extended. The device adopts a mechanical type normally closed as a sensor to have little wrong alarm, and the cost is low.

Description

The alarm of forcing open the door

The utility model is a kind of alarm of forcing open the door, and can send audible alarm when thief is forced open the door.

Confirm according to the public security department data: most burglaries are by committing theft in the inlet chamber of forcing open the door, and the door lock lock cross-peen that is installed on the doorframe when forcing open the door must be shifted.Why present known burglar alarm is difficult to enter family's application of the common people, is because following shortcoming is arranged:

1, adopt mains powered to keep away the possibility of cutting off the electricity supply before unavoidable thief is forced open the door alarm being lost efficacy, and the cost height.

2, its sensor just can detect after can only be in people's inlet chamber, and can not distinguish the difference of house-owner and thief, brings the trouble of entering at every turn and also will remove password or turn-offing alarm sound to the user.

The purpose of this utility model is to avoid above-mentioned prior art weak point and provides a kind of is power supply with the dry cell; Cost is low and easy to install and use and can keep thief outside of the door and just can send the alarm of forcing open the door of audible alarm.

Special character of the present utility model is that design proposal is: be serially connected with a closed type mechanical switch K and resistance R 1 and big resistance resistance R 2 in the static loop of alarm of forcing open the door, on R1 and dividing point that R2 is connected, be connected to a testing circuit, this testing circuit is made up of a positive-negative-positive transistor G1 and a resistance R 3, the base stage of this transistor G1 links to each other as the dividing point of input end with resistance R 1 and R2, emitter and collector is connected across between the both positive and negative polarity of power supply through a resistance R 3, and emitter links to each other as the base stage of output terminal with another positive-negative-positive transistor G2.Composite switch circuit of the common composition of transistor G2 and G3 is integrated circuit (IC) 1 and IC2 power supply.

Further specify as follows in conjunction with the accompanying drawings:

Accompanying drawing is the utility model circuit theory and scheme of installation, and two dotted lines represent that respectively two contact K-1 of closed type mechanical switch K and K-2 are at doorframe M with do not represent two contact K-1 and the installation site of K-2 on doorframe M and door lock lock cross-peen S of closed type mechanical switch K among the figure.K-1 is that fixed juncture is fixed on the doorframe M; K-2 is that movable contact is installed on the lock cross-peen S.When nobody prizes lock cross-peen S, K-1 and K-2 are closed together, make the testing circuit detection of forming by PNP transistor G1 and resistance R 3 be in cut-off state less than forward voltage, thereby also make the composite switch circuit of forming by transistor G2 and G3 be in cut-off state, can not be integrated circuit (IC) 1 and IC2 power supply, the loudspeaker B alert sound equipment of not transmitting messages.

When the people prizes door lock, thereby must make the displacement of lock cross-peen make the movable contact of the K-2 that is installed on it break away from fixed juncture K-1 and be in open-circuit condition, G1 in the testing circuit is in conducting state at this moment, thereby make transistor G2 and G3 conducting simultaneously, directly power for audio frequency amplification circuit IC2 on the one hand, supply required supply voltage by a current-limiting resistance R4 and stabilivolt W for audio ic IC1 on the other hand.The sound signal of IC1 output enters the input end of IC2 by capacitor C 1, sends audible alarm by capacitor C 2 by loudspeaker B after amplifying.

The utility model embodiment powers and adopts the 9V packed cell, and resistance R 1 is 100K Ω, and R2 is 22M Ω, and R3 is 300K Ω, and R4 is 1K Ω.Transistor G1, G2 and G3 are 2N5401.Stable pipe W is 0.5 watt 3.5 volts, and capacitor C 1 is 4.7 μ F, and C2 is 220 μ F, and loudspeaker B is 8 Ω, and integrated circuit (IC) 1 is LH9561, and IC2 is LM386, and two contacts of closed type mechanical switch K are made by oneself with conducting metal respectively.

The utility model compared with prior art has the following advantages:

(1) need not to adopt mains supply, the chance that thief is not had cut off the electricity supply. Extremely low quiescent dissipation can prolong the useful life of dry cell greatly.

(2) exempted the trouble that needs to remove alarm sound after the user enters at every turn.

(3) adopting the normally closed point of mechanical type is sensor, not only significantly reduce mistake utmost point rate, and cost is low easy to utilize.

Claims (2)

1, a kind of alarm of forcing open the door, it is characterized in that: in the static loop of this alarm of forcing open the door, be serially connected with a closed type mechanical switch K and resistance R 1 and big resistance resistance R 2, be connected to a testing circuit on R1 and dividing point that R2 is connected, this testing circuit is made up of a positive-negative-positive transistor G1 and a resistance R 3; Its base stage is connected with R2 with resistance R 1 as input end, and emitter and collector is connected across between the both positive and negative polarity of power supply through a resistance R 3.

2, the alarm of forcing open the door according to claim 1 is characterized in that: the fixed juncture K-1 of described closed type mechanical switch K is fixed on the doorframe M, and movable contact K-2 is mounted on the lock cross-peen S of door lock.