Dual Tone Power Failure And Resumption Alarm Circuit Using Timer Ic And A 9V Battery

Author: Manikandan KJ © Here is another audio annunciator used in factories, industries, hospitals, auditoriums, theatres, etc. to indicate the power failure and resumption. The circuit will give a long beep on power resumption and an intermittent beep when power fails. The power failure alarm circuit that I posted earlier will activate the alarm (continuous tone) only for a few …

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Fire Alarm Using Thermistor And Ic 555 | Working Of Fire Alarm

Authоr: Prаdеер G       Source:EFY  Thіѕ project саn еffесtіvеlу be used as a tеmреrаturе-ѕеnѕіng fіrе alarm. Here, an NTC thеrmіѕtоr іѕ used аѕ the temperature ѕеnѕоr. Rеѕіѕtаnсе of thе NTC thеrmіѕtоr dесrеаѕеѕ wіth аn іnсrеаѕе in temperature. Parts Lіѕt: Semiconductors:IC1,IC2-NE555 TImеrT1-BC547 NPN TrаnѕіѕtоrLED1-5mm Rеѕіѕtоrѕ(1/4w,+/-саrbоn):R1- 22KR2- 4.7KR3,R6- 1KR4,R7- 56KR5- 680ER8- 10EVR1- 100K Pot Capacitors:C1,C6- 100uF,25VC2- 2.2uF,25VC3,C5- 0.01uF,сеrаmіс discC4- 0.047uF, сеrаmіс disc …

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Burglar Alarm Using NPN(BC548)And PNP(SK100) Transistor

The burglar alarm circuit shown here sounds an alarm when the wire loop is broken.The system is implemented by installing a sensing loop, which is basically a thin copper wire. This way, the loop is both invisible and brittle enough to break easily and initiate the alarm mechanism.At the time of an intrusion, the loop breaks and this causes the …

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Water Level Indicator Circuit Project Using IC 555 With Motor Dry Run Protection Alarm

Author: Manikandan K J Components Required:Resistors (All 1/4W)R1 – R6 – 1MR7 – R12 – 220KR13 – R17 – 1KR18 – 3.3KR19 – 1MR20 – 100K (Preset)R21 – 1KR22 – 1.5K Capacitors:104(0.1uF) – Ceramic Disc – 1 no.100uF,25V – 1 no.470uF,40V – 1 no. IC:U1- CD4049 (with Base)U2-555(with Base) Diodes:D1 – LEDD2 & D3- IN4148DB1- W04 (Bridge Rectifier) Transistor:S8550 PNP Relimate Connector:Sensor – 8 …

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