Circuit Summary
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The power supply resumption alarm circuit will provide audible and visual effects the moment power is resumed.
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Power fluctuations can damage your electronic devices like TV, refrigerator, etc. For this we use power stabilizers, but they are also expensive and consume energy.
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This circuit is less expensive to build and also consumes less power.
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This circuit needs just 9V to work.
Principle behind the Circuit
The circuit shown here is easy to set up. In this circuit, IC1 is assembled in an unusual way. When power resumes, pin 2 of IC1, which is connected through capacitor C1, is grounded and becomes low, while pin 3 of the same IC switches to high. In turn, pin 4 of IC1, which is a reset pin, switches to the high state for approximately 10 seconds. When the voltage at C1 reaches 2/3 of the supplied voltage, the capacitor starts discharging and the output switches low, grounding pin 4, which is a reset pin and therefore the dropped circuit is out of action.
The alarm circuit is composed with the help of the second IC i.e. IC2. The astable mode of this IC is used in this circuit and the working frequency of the IC is 1 KHz. The moment the output of IC1 is in high state, IC2 comes into action.
Thus, the speaker will generate the alarm for approximately 10 seconds. After this period, IC1 returns to its stable state. With the help of pin 7, capacitor C1 discharges quickly and the circuit is ready for the next recognition as pin 2 of IC1 is in low state. Then, when the supply is interrupted next time, it will generate a sound. LED is used in the circuit to provide a visual effect.
Components needed to build the circuit
CI
IC1, IC2 NE555
Resistor
R1 1 million
R2 1K
R3 68K
R4 330K
Capacitor
C1 10uF
C2,C3 0.01uF
C4,C6 470uF
C5 100uF
LED
LED1 Any color
9V power supply
Fig. 1: Prototype power resumption alarm circuit based on 555 IC
Circuit diagrams
| power supply-resume-alaram_0 |  |
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