NE555 Timer- Monostable Circuit

When connected in 'Monostable' mode the 555 timer will switch on and then go into 'sleep' mode. When triggered it will switch on for a set period of time and then go back into 'sleep mode'. This is an example of a timer circuit. By swithching the polarity of the output (i.e an LED connected from pin 3 to 0V to an LED connected from pin 3 to +V) a time delay can be made. The values of the resister and capacitor on the right hand side will determin the amount of time the output will stay on or the delay. The 0.01uf capacitor is not neccessary for the circuit to function, however it stabalises the circuit and keeps it running at a steady voltage.

Parts List

• 1 NE555 Timer
• 2 1K ohm resistors
• 1 330 ohm resistor
• 1 variable capacitor
• 1 0.01 uF capacitor
• 1 Rocker switch
• 1 Push to make switch
• 1 LED
• 9V power supply (e.g 9V PP3 battery)
• Breadboard or similar

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