Circuit Design And Technology

Posted on Feb 5, 2014

555-Timer has vast application in electronics. In my recent post I showed you other forms in which a 555-Timer could be applied. Today, we shall use 555-Timer in a Monostable Multivibrator configuration to trigger a Driver (Transistor) in energizing a relay and in turn operate a lamp of 230V AC when the relay normally open contact is energized. Ab

Circuit Design And Technology
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ove shows a configuration of a 555-Timer connected in a monostable pattern. This is achieved by connecting Pin 6 and Pin 7 together (bridged using a jumper). Then, connect Pin 8 to the supply rail (power supply line). Then, connect a 10k © resistor from pin 4 to the supply rail and then, also connect a capacitor (electrolytic capacitor) of 100 µF 16v from that same pin 4 to ground (0v or neutral line of the power supply). The essence of the resistor capacitor network at pin 4 is to slow down or stop immediate start up of voltage at pin 4 when the power source is turn On initially. This will eliminate false triggering of the 555-Timer from operating the Lamp when we didn`t even intend for nit to be operated. Now, from pin 7, connect a resistor of 100k © variable resistor in series with a 10k © fixed resistor to the supply rail (power supply line). That is to say that, the two resistors will be in series and one of its terminals will be connected to pin 7 and the other terminal will be connected to supply rail. The fixed resistor is to ensure that the variable resistor when adjusted to 0 © will not affect the circuit in anyway. And now, connect a 1000 µF 16v capacitor from pin 7 or pin 6 to ground (negative rail or neutral line of the power source). Lastly in regard to the first stage, connect a resistor of 10k © in series with pin 2 (Trigger Pin or Input) and the supply rail. Then, connect a push button soft switch between...

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