# Time delay with one 555

It means the timer does not give the contact changeover until the preset time is reached. See the picture that, the input supply is given to the timer coil, but there is no output until the preset time. After reaching the preset time the timer makes the contact changeover. Such Timers are called On delay timers.
To create a time delay in a circuit, a Monostable 555 Timer is required. Calculate the value of the resistor necessary to provide a minimum output time delay of 500ms if a 10uF timing capacitor is utilized.

Many electronic circuits frequently 205 require the brief delay of a pulse. Such a delay, here between 100 ps and 100 s, is easily provided by a simple circuit based on the popular 555. That is more than adequate for most applications. The output of the 555 can go high only if the potential at pin 2 drops below a third of the level of the supply voltage, provided that the level at pin 4 is high. In quiescent operation, the level at pin 4 is low and C1 is charged via T1 so that the output is low. Then the input goes high, Ti is switched off and C1 is discharged via R1. In that con-uni on, the reset state is canceled, and alter a time delay that depends on the state of discharge of C1 the output of the 555 goes high. The time delay in seconds is calculated from t = 0.69R14C1, where R1 must be greater than or equal to 10 kΩ.

## 555 Timer Output

A collection of 555 circuits using the 555 Timer as an astable oscillator with different duty cycles.

The standard TTL 555 can operate from a supply voltage between 4.5 volts and 18 volts, with its output voltage approximately 2 volts lower than its supply voltage VCC. The 555 can source or sink a maximum output current of 200mA, (but it may get hot at this level), so the circuit variations are unlimited. Note that the CMOS versions of the 555, the 7555, and the 7556 may have different voltage and current ratings.

The 555 Timer IC got its name from the three 5KΩ resistors that are used in its voltage divider network. This IC is useful for generating accurate time delays and oscillations.

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