Why 555 ic is called 555

Applications : The can operate as a flip-flop, if the DIS pin is not connected and no capacitor is used. Uses include bounce-free latched switches. Here is a simple configuration of the Timer used as a low frequency oscillator. Or it can be used as a LED flasher circuit having delay of 2. If one 0f the resistor is replaced by a 10K pot then there will be also an option for reducing or increasing the time interval.

Search Search for:. PIN 3 : Pin 3 or the output pin is driven to approximately 1. Here, POT resistance refer to the potentiometer adjustment, and the resistance level of that particular side of the pot through which the capacitor C charges.

Then depending on which portion of the resistance is charging the capacitor, the value could be used in the above formula. If it's the 3 K side adjustment that is charging the capacitor, then the formula could be solved as:.

On the other hand, if it's 2 K that's on the charging side of the pot adjustment, then the formula may be solved as. Please remember, in both cases the C will be in Farads. So you must first convert the microfarad value in your schematic into Farad, for getting a correct solution. This IC circuit might seem recognizable to a lot of visitors because it is among the several versions of circuits from the common timer circuits. That does not essentially reduce its usefulness though.

Simply because, a flexible pulse generator having a adjustable duty cycle can be a very handy equipment for any electronic workshop. In contrast to the conventional astable circuits that are generally implemented, the resistors between pins 6 and 7 includes P1, P2, R2, DI and D2. References: Stackexchange. If you have any circuit related query, you may interact through comments, I'll be most happy to help!

Your email:. Hi, current sensing transformer would be unnecessarily complex to calculate and build, instead an opamp or resistive network could be applied for the same results with perfect accuracy.

If you search my blog you may find a few of them , however if you have specific questions , I can clarify them for you separately…. Hi Swagatam, I have a circuit that uses a nep astable timer that is on for seconds 4-min and is off for 1 second, then on for sec, etc. My problem is the timing is off about 1. Is there a way to make the power up timing cycle be the same as the other cycles? Hi Swagatam, I recently ask you about a problem of my timing circuit using timer was not correct at initial start up.

You suggested I add a 10k resistor to ground and a 10k resistor to voltage and a 10uF cap to ground from pin 4 of the timer. Q 2 is the reset transistor, where a pulse applied will reset the whole timing circuit. The output from the flip-flop is amplified by the power amplifier block. Ground GND. The ground terminal of external circuit as well as power supply V CC ground terminal is connected to the GND Ground terminal of timer. This pin is either grounded or connected to the negative rail.

Connection using a resistor is not recommended to avoid heating up of the IC because of the stray voltage accumulated inside it. This pin is the input trigger pin to the IC and activates the timing cycle. A low signal at this pin triggers the Timer. Required current at this pin is 0. To avoid false triggering due to noise, the pin requires a pull up connection. Voltage at this pin is 1. This terminal is used for getting output and connected with load. At any instant, its value is low or high.

This is the output pin of the Timer. Output of the Timer depends on the duration of timing cycle of the input pulse. The output can either sink or source current, at maximum mA. Without taking into account the previous state of output, by providing a trigger pulse to this terminal resets the device. Its output becomes low. The reset pin is either not connected or connected to the positive rail.

A logic LOW signal at this pin resets the Timer regardless of its input. The required reset voltage is 0. Control Voltage. There are two third positive voltages of the total Supply voltages V CC at control voltage terminal. Thus, it becomes a part of the comparator circuit. Generally, a capacitor is connected between ground and voltage control terminals. This is also a generally non-connected pin or connected to ground through a 0.

For some applications, this pin is required to control the threshold voltage at the upper comparator and is connected to an external DC signal, to change the duty cycle. Threshold Voltage. Threshold voltage and control voltage is the two inputs of comparator circuit.

The circuit compares the available voltage at threshold voltage terminal to the available reference voltage at control terminal. If the available voltage at threshold terminal Pin 6 is greater than the control voltage i. This pin provides threshold voltage to the upper comparator. It is connected to non-inverting terminal of the upper comparator. Required current is 0. When output is low, then Discharge terminal provides a low resistance discharge path to the externally connected capacitor.

However, it acts an open circuit, when output is high. This pin provides a discharge path for the timing capacitor through the NPN transistor. A discharge current less than 50 mA is required to avoid damage. This chapter explains about Timer in detail. In this section, first let us discuss about the pin diagram of Timer IC and then its functional diagram. The significance of each pin is self-explanatory from the above diagram.

The pictorial representation showing the internal details of a Timer is known as functional diagram.