Time Delay Circuit Diagram. The r is a resistor and the c is a capacitor. Simple timer circuit diagram the figure 1 shows a very simple timer that will activate the relay for around 45 seconds after pressing the push button s1.
There is a delay before the output turns on. The entire circuit is powered by 5v using 7805 voltage regulator. When the power to the circuit is turned on the 1000µf capacitor charges through the 100kω variable resistor.
The transistor has been provided with the usual base resistor for the current limiting functions.
The 555 timer starts timing when switched on. How we achieve the delay effect is through the use of a capacitor. We have to configure 555 timer in mono stable mode to build a timer. A led which is used here just indication purposes behaves like the collector load of the circuit.
