Two Tone Alarm | Electronic Project Circuits

Posts Tagged ‘Two Tone alarm’

Two sirens sound with ic 555

Operation of the circuit. Circuit is divided into three parts: low frequency production. The manufacturing high frequency and extension of production low frequency is obtained from IC1 connected to astable multi vibrator circuit frequency is set by R1, C2 frequencies that are coming out of pin 3 is about 1 Hz through R2 to be good 5. of IC2, a division produce high-frequency input at Pin 5 will tone the origin of oscillator IC2 is the ripple of voltage from the output of IC1 frequency of IC2 is being set by R3, C3, which, if C3 value. will be very low tone if C3 is less treble The output will have to stand out in three legs of IC2 to stimulate B of Q1 to amplify signals that drive speakers.

Be the first to comment - What do you think? Posted by admin - June 12, 2010 at 7:07 am

Categories: Alarm systems Tags: 555 siren alarm, Two Tone alarm

Electronic siren circuit with two transistor

Operation of the circuit is Q1 and Q2 will work with R3, R4 and C2 is a frequency generator circuit with output connected to LED1 and speakers SP1. When I press the switch S1 to the C1 will begin to charge allows the voltage to pin B of Q1 increase other. The Q1 is working and Q2 is working with at the C1 charge full cycle will stop oscillator speaker is not.
The LED1 light and hold the release the pressure switch S1, resulting in C1 will start discharger through R3, Q1 to ground. The oscillator circuit sound Sirens in the lower out. If we press the switch S1 and then quickly leave many. The sound will be as continuous as C1 to charge and discharge alternately continuously.

Be the first to comment - What do you think? Posted by admin - June 6, 2010 at 11:33 pm

Categories: Alarm systems Tags: electronic siren circuit, transistor oscillator, Two Tone alarm

Forget door alarm circuit

This circuit uses to warn when forget shut the door. By use switch stick at the door, if do not shut the door switch will off as a result will have a voice warn from a loudspeaker hear immediately.

The work of the circuit , when stick switch S1, at the door which in usual time switch still pressed the circuit will build the frequency upwards with Q1,Q2 C1. When the circuit will work to have current flow through R1 reach C1. By C1 do something charge enough then have current flow get along well with B of Q1. It make Q1 work cause Q2 lead current flow reach a loudspeaker.

At the same time C1 will discharge change R1 , when discharge be finished. It make voltage at a pin B of Q1 be valuable a little make Q1 and Q2 stop work. And have current flow through R1 reach C1 again. The work in this character will cause the loud sound goes up. But when shut the door make switch S1 pressed. Q1 can not can work. Because voltage at a pin B be 0V make the circuit doesn’t work and have no the sound comes out from a loudspeaker.