Buz - 3v to 24V DC buzzer (continuous or intermittent)
Led - 3mm 0r 5mm L1 - Green L2 - Red
S1 - Normally Open Momentary Switch
Sensor - Contact type metal sensor or float switch or stainless steel spoon:)
Integrated Circuit: U1 - 7812 U2 - 555 Timer IC
Prototype
Working
This circuit produces an audible alarm when the water level in a rain or water tank rises above a preset level and overflows. It will sound an alarm whenever the water level reaches the top position in the overhead tank, thus it alerts one to turn off the motor to prevent water wastage.
The purpose of this circuit is to detect when there is an overflow of water in a tank and stop it from continuing to rise which would cause flooding. This can be useful in many different places where there are tanks of water like swimming pools, fountains or overhead tanks for example.
It has a power indicator and a full tank led indicator apart from the alarm. The power to this device can be kept "on" all the time (24 X 7). We can turn off the alarm sound by pressing the momentary switch. We can use contact type sensors or float switches to sense the water level inside the tank. We can use this circuit in the overhead tank, swimming pools, underground sump, aquariums, etc.. in order to monitor the top level.
This circuit can be powered by a 9 or 12v step-down transformer of current rating ranging from 200mA to 500mA. We can use speaker wire to connect the device to the sensor or float switches inside the tank. For alarm, here I have used a continuous tone buzzer. We can also use musical buzzer or a recordable chip with a slight modification in the circuit.
This is a very simple circuit built using only a few components to detect ac mains power failure and its resumption. The heart of the circuit is the most popular timer Ic 555 which is wired as monostable multivibrator. ac power supply failure alarm circuit…
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