Description: In the monostable mode, the 555 works as a “one-shot” pulse generator. Other applications of monostable mode include timers, pulse-width modulation (PWM), missing pulse detection, touch switches, frequency divider, capacitance measurement, bouncefree switches and so on.
- READ MORE ABOUT MONOSTABLE MODE
- Download FREE simulators for learning 555 timer.
- An example of monostable mode
The following schematic has been taken from buildcircuit.com. The following circuit can be used for making a touch switch, light operated switch, clap switch, dark sensor, etc.
EXPERIMENT 1: DARK SENSOR USING LDR AND 555
Use VR1(variable resistor) for adjusting sensitivity of the dark sensor. You can use fixed resistor in place of the variable resistor.
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EXPERIMENT 2: DARK SENSOR USING PHOTODIODE AND 555
Just replace LDR with a photodiode, connect cathode to PIN 8 and anode to pin 2 of 555, it simply works for the photodiode also.
EXPERIMENT 3: TOUCH SWITCH
A minor modification in the circuit makes it work as a touch switch.
EXPERIMENT 4: MAKE A CLAP SWITCH