School Bell Alarm
₹599 – ₹949
- Product Code: LGKT034
- Power supply: No battery included, Includes DC adapter if required with the kit
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Shipping DetailsUsually delivered in 2-3 days International Shipping Not Available
In the kit School Bell Alarm when peon wants to beep the school bell then they have to press the momentary switch then school bell is on for few second according to the value of resistance and capacitance. We can change the on time the changing by capacitor and resistance.
In the kit School Bell alarm we can change this ‘on’ time by changing the values of resistor and/or capacitor depending upon your requirement. The micro switch (S1) is such adjusted so that when the peon pressed momentary switch. This press of the switch sends logic low to the trigger pin2 of the LM555 IC which generates an active high output on pin 3.The IC is used in mono-stable state. The value of the time for high pulse on each trigger at input is dependent on the value of the resistor and the capacitor. The output from the LM555 drives the ULN2803 IC (it act as current amplifier to meet current requirement to drive the relay). It is an inverted IC means when input is low output is high and vice versa. This IC 555 drives the relay to activate the light which is a DC buzzer. The relay acts as electromagnetic switch to switch the high voltage to activate the DC buzzer and activate the DC supply across the buzzer.
- Dimensions (cm) LxWxH: 18 x 15 X 7
- Weight (kg): 0.5