To achieve any arbitrary duty cycle, R2 can be moved to be in series with pin 7, the discharge pin. The duration of the high-output interval during the charging of C1 is then 0.
The total time period, T, is 0. The first thing i suggest you is to use more the documentation about the IC in the center, because the rest of the schematic is for making the ic working. And a lot of information are in the technical documentation.
Is it working as a voltage divider? Pin 5. By applying a voltage to this pin the width of the output signal can be varied independently of the RC timing network. When not used it is connected to ground via a 10nF capacitor to eliminate any noise. A great tutorial for you on the oscillator mode astable , timer is monostable Astable mode from www.
Potentiometer in the schema controls the pulse width i think. When you encounter a component you don't know, it is best to read its datasheet for basic information at first. As you can see here from the block diagram from wikipedia, Pin 7 provides a direct connection to ground or causes pin 7 to be an open circuit depending upon the state of the RS-latch. This means that you either have both R1 and R2 as a current path to charge capacitor C1 on the charge cycle while pin 7 is open or you have R2 connected to ground on the discharge cycle.
When the capacitor is charged to a certain level, it causes pins 6 to trip causing the RS latch to change state. This forces Pin 7 to short to ground. The capacitor will discharge through R2 and Pin 7 until Pin 2 threshold is tripped. This results in a output high time of the time it takes to charge the cap up to pin 6 threshold level, and an output low time of the time it takes to discharge the cap to pin 2. Lastly, you ask what Cap2 does. As you can see from the diagram, it's connected to pin 5 which is the trigger set-point side of the comparators.
This capacitor is acting as a bypass capacitor which helps to stabilize the voltage set points. If this is is switching, it's possible that it's drawing significant current during the discharge phase. In that case, the VCC would droop. The capacitor at pin 5 helps prevent the trigger voltage from drooping as well. These ICs are used as an astable and monostable multivibrators in digital logic probes, DC-DC converters , tachometers, analog frequency meters, voltage regulators, temperature controlled and measurement devices.
The IC timer is a one type of chip used in different applications like an oscillator , pulse generation, timer. The designing of IC timers can be done by using various electrical and electronic components like transistors , resistors, diodes and a flip flop.
The operating range of this IC ranges from 4. The functional parts of the timer IC include flip-flop, voltage divider and a comparator. The main function of this IC is to generate an accurate timing pulse. In the monostable mode, the delay of this IC is controlled by the external components like a resistor and capacitor. The timer IC consist of 8-pins where each pin has some function. The pin configuration of this IC is shown below. The output of the timer depends on the amplitude of the external trigger pulse that is applied to the trigger pin.
Pin-4 is a RST pin. When the negative pulse is applied to this pin to disable or reset, and false triggering can be neglected by connecting to VCC. Pin-5 is the control voltage pin used to control the pulse width of the output waveform and also the levels of threshold and trigger. When an external voltage is applied to this pin, then the output waveform will be modulated. Pin-6 is the threshold pin, when the voltage is applied to threshold pin, then it contrasts with a reference voltage.
The set state of the FF can be depends on the amplitude of this pin. Pin-7 is the discharge pin, when the output of the open collector discharges a capacitor between the intervals, then it toggles the output from high to low.
Vice versa, if the voltage at the negative input terminal is higher than the voltage at the positive terminal, the comparator will output 0. So using the three pins, Trigger, Threshold and Control, we can control the output of the two comparators which are then fed to the R and S inputs of the flip-flop. The flip-flop will output 1 when R is 0 and S is 1, and vice versa, it will output 0 when R is 1 and S is 0. The Q-bar output of the flip-flip goes to the output stage or the output drivers which can either source or sink a current of mA to the load.
For that purpose we need two external resistors and two pushbuttons. The two pushbuttons are connected between these pins and the ground, so if we hold them pushed the input state will be low. Initially, the two comparators outputs are 0, thus the flip-flop output as well as the output of the Timer are 0. If we press the Trigger pushbutton, the state at the Trigger input will become Low, so the comparator will output High and that will make flip-flip Q-bar output go Low.
The output stage will invert this and the final output of the Timer will be High. For making the output Low we need press the Reset pushbutton, which resets the flip-flop and the entire IC.
The trigger input is held High by connecting it to VCC through a resistor. That means that the trigger comparator will output 0 to the S input of the flip-flop. On the other hand, the Threshold pin is Low and that makes the Threshold comparator out 0 as well. The Threshold pin is actually Low because the Q-bar output of the flip-flop is High, which keeps the discharge transistor active, so the voltage coming from the source is going to ground through that transistor. In order to change the Timer output state to High we need to press the pushbutton on trigger pin.
That will ground the trigger pin, or the input state will be 0, thus the comparator will output 1 to the S input of the flip-flip. This will cause the Q-bar output to go Low and the Timer output High.
At the same time, we can notice that the discharge transistor is turned off, so now the capacitor C1 will start charging through the resistor R1. In that case, the Threshold input voltage will be higher and the comparator will output 1 to the R input of the flip-flip. This will bring the circuit into the initial state. The Q-bar output will become High, which will activate the discharge transistor as well as make the IC output Low again. We only need two resistors and a capacitor.
The Trigger and Threshold pins are connected to each other so there is no need of external trigger pulse.
Initially, the voltage source will start charging the capacitor through the Resistors R1 and R2. That means that the Q-bar output is 0 and the discharge transistor is closed. At this time the output of the Timer is High. This will active the discharging transistor and now the capacitor will start discharging through the resistor R2 and the discharging transistor.
At this moment the output of the Timer is Low.
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