volt control 555 timer - use in electronic circuits by jason john

by:KEBO      2019-10-19
There are many circuits using the 555 timer IC.To learn more, you must explain the square diagram in detail.The basic 555 timer consists of two Op Ampsreset flip-Trigger and two transistorsAn operational amplifier is designed to be used as a comparator.There will also be a voltage divider circuit built with the help of a resistor network.Each comparator is used to compare the threshold voltage and the reference voltage.The first comparator COMP 1 is compared to the reference voltage 2/3 Vcc.The second comparator COMP2 is compared to the reference voltage 1/3 Vcc.After comparing the voltage, their respective outputs are given the input of the Flipflop.
From the pin configuration of the 555 timer, you can see that the transistor is placed as a charger with the collector terminal connected to pin 7.The output of the trigger is given to this transistor.According to the output, the transistor switches to its cutting-Leave or saturation zone.
When the transistor is in the saturation phase, it provides a discharge path for the capacitor connected externally.Another separate connection is about the Reset terminal.The pulse given to this terminal will reset the entire 555 timer circuit.This pulse is provided with the help of another transistor.
COMP 1 consists of two inputs, A threshold input [Pin 6] and A control input [Pin 5].In most cases, pin 5 is not used, so the control voltage will be equal to 2/3 Vcc.This pin is mainly used to change the switch level.If not used, place a capacitor with a very small value between pin 5 and ground.This will help stop the noise and thus stop the false trigger.The capacitance value is 0.01 nano farad.Output of COMP1 to set [S] input of S-R Flip-Flop.When comparing the voltage, if the reference voltage is less than the threshold voltage, the output will enter a high state.This high state causes the transistor to discharge through the external capacitor of pin 7.Pin 3 is the output that receives a free signal from the flipflop.So it will be low.All of these conditions will be in standby as long as COMP 2 triggers a flipflop.Another point to note is that COMP 1 can only help provide high output for flipping
.COMP 1 does not set the flip even if the threshold voltage is less than the reference voltage-Change again.For the flip-To reset, the threshold voltage must be below 1/3 Vcc.Once this happens, COMP 2 provides a trigger in the flipSo force it to provide low output.This in turn produces a high output on the output pin because the flip resetThe trigger turns the discharge transistor off.Like COMP 1, COMP 2 can only be flippedLow output flop.Unable to set status again.
Therefore, the 555 timer rationale is that when the threshold voltage exceeds the reference voltage of 555 Vcc, the 2/3 timer produces a low output.This causes the discharge transistor to turn on.In order for the output to be high, the threshold voltage must be below 1/3 Vcc.This will cause the discharge transistor to enter OFF mode.You must also note that it must be connected to Vcc when the RESET pin is not used.
Many electronic circuits using the 555 timer are now being designed.

Although they are used in other electronic circuits, they are mainly used to perform any of the above operations.

A static multi-vibrator is used to generate rectangular waves.Since the circuit does not require an external trigger when switching the output state, it is also called a free-running oscillator.The connection must be exactly the same as the circuit diagram.That is, pins 4 and 8 should be connected to the Vcc power supply.Pin 1 should be grounded.The output must be taken out of pin 3.Pins 2 and 6 should also be connected to the capacitor and then to the ground.The most important thing is the resistance and capacitance of the external connection.Their value determines the switching time of the 555 timer.

In order to obtain a single-stable multi-vibrator, there should be a change from stability to quasi-statestable.To do this, a trigger input such as a very small width negative pulse must be given with a magnitude greater than 2/3 Vcc to 2nd pins of the 555 timer IC.But in the static state of the output, the input must remain at Vcc v.Pin 1 should be in a ground state.As usual, don't forget to ground the fifth needle with 0.01 micro-Farah capacitance is between the two.There should be resistance between pins 6 and 8.The 8-pin is connected to the positive power supply.

This electronic circuit is often called a voltage-frequency converter.The reason for this is because by changing the voltage in the input, it is easy to change the frequency obtained in the output.To make this possible, the fifth pin of the 555 timer gets the external voltage with the help of the potentiometer.Therefore, the change of the pot value will change the control voltage of the circuit.When the control voltage increases, the discharge time of the capacitor increases, so the output frequency decreases.When the control voltage is reduced, the capacitor discharges quickly, so the frequency in the output increases.

As specified by the name, the circuit is used to generate a ramp circuit.The basic idea is to charge the capacitor with the help of the voltage source through the resistor.This will generate an exponential waveform.At the same time, the capacitor is charged from a constant current source that helps to generate the slope.Another important issue to pay attention to is the transistor used.In addition to other electronic circuits that use a 555 timer, PNP transistors are used here.This helps to generate a constant charging current.
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