Posted by Circuits Arena on Saturday, 17 January 2015
Door Alarm Circuit Diagram is the artlcle explaining Door Alarm Circuit Diagram: This is a straightforward circuit that activates associate alarm once there's a play the door or there sq...
Door Alarm Circuit Diagram:
This is a straightforward circuit that activates associate alarm once there's a play the door or there square measure any vibrations because of movement of serious merchandise or piece of furniture. The circuit uses promptly out there parts.
Circuit and dealing
The circuit is constructed around quad-opamp LM324 (IC1), that is designed in electronic equipment mode. It uses the electricity part of a piezo buzzer because the input sensing element, 2 transistors BC547 (T1 through T2), a piezo buzzer and a few different parts for the alarm circuit. Fig. one shows the
circuit diagram of the
door-knock alarm.
Fig.Circuit diagram of a door alarm
The reference voltage at pin three of IC1 is about by trimming potmeter VR1. The electricity part plate is mounted at the centre of the door victimisation violoncello tape. Apply atiny low amount of adhesive on the sides between the plates. Wires from the piezo part square measure connected at CON2. These generate associate input pulse once vibrations square measure caused by sound on the door. the heartbeat is amplified by op-amp A1 of IC1. Remaining 3 op-amps of quad IC LM324 aren't used here.
The output of A1 of LM324 from pin one is more amplified by transistors T1 and T2 to drive the piezo buzzer or relay. as a result of the presence of high-value capacitance C5, the buzzer remains active for many seconds. The circuit is hopped-up by 9V/12V power provide. Sensitivity of the circuit will be adjusted by 1M potmeter VR1.
