- #IN PROBLEM 5 16 WE SAW HOW AN EDGE TRIGGERED FLIP FLOP GENERATOR#
- #IN PROBLEM 5 16 WE SAW HOW AN EDGE TRIGGERED FLIP FLOP SERIES#
The voltage across its the volatge VE applied to the emitter of UJT. When switch S is first closed, applying power to the circuit, capacitor C starts charging exponentially through R to the applied volatage V. The UJT relaxation as a relaxation oscillator is shown in Figure 3, generates a voltage waveform VB1 (Figure 3), which can be applied as a triggering pulse to an SCR gate to turn on the SCR. Since the emitter base junction voltage VBE for a fixed current decreases by about 2 mv/co, therefore the ramp speed increases with the temperature. The draw back of constant current ramp circuit is that it makes the sweep rate as a function of temperature. If the emitter to base voltage VEB remains constant with time after the switch S is opened, then the collector current will be a constant whose normal value, IC = hFB. The value of emitter current is given by the relation.įOR STUDY MATERIAL OF IT SPECIALIST OFFICER CALL 08961556195 OR EMAIL = ( VEE - VEB ) / RE This characteristics may be used to generate a quite linear ramp by causing a constant current to flow into a capacitor. We know that except for very small value of collector to base voltage, teh collector current of a transistor in the common base configuration is very nearly constant, when the emitter current is held fixed. At the end of time TS, the capacitor discharges and the voltage is again zero.įigure 2: Constant Current Ramp Generatorįigure 2 shows a circuit to generate a ramp using constant current from a common base transistor. It may be observed that the transistor switch is OFF only for the gating time (TS).
This equation represents an approximately linear waveform. Then taking only the first term of the power series, the output voltage.
#IN PROBLEM 5 16 WE SAW HOW AN EDGE TRIGGERED FLIP FLOP SERIES#
If t / RCC << 1, then above relation may be expanded into a power series in t / RCC. The charging curve ignoring VCE (sat) is given by the relation.
As a result of this, the capacitor voltage rises to a target value VCC with a time constant RCC. a negative pulse is applied the transistor turns OFF. Actually its value is equal to VCE (sat).
#IN PROBLEM 5 16 WE SAW HOW AN EDGE TRIGGERED FLIP FLOP GENERATOR#
one shot) or an Astable multivibrator.įigure 1: (a) RC Ramp Generator (b) Input and Output WaveformsįOR STUDY MATERIAL OF IT SPECIALIST OFFICER CALL 08961556195 OR EMAIL the transistor is biased ON and operates in the saturation region. It may be obtained from a Monostable multivibrator (i.e. This circuit requires a gating waveform Vi as shown in Figure 1(b). In this method a constant current is approximated by maintaining nearly constant voltage across a fixed resistor in series with a capacitor.įigure 1 shows the basic circuit of RC ramp generator. In this method a capacitor is charged linearly from a constraint current source. In this method a capacitor is charged through a resistor to a voltage which is small in comparison with the supply voltage. This topic consider the circuits employed in the generation of voltage and current sweeps.Īlthough there are a number of methods of ramp generation, yet the following are important from the topic point of view. Linear current ramp generator are extensively used in television deflection systems. Linear ramp generators are also known as sweep generators, from basic building blocks of cathode ray oscilloscope and analog to digital converters. Voltage and current linear ramp generator find wide application in instrumentation and communication systems. Short notes on digital electronics for specialist officer it exam by das sir,kolkata (08961556195)įOR STUDY MATERIAL OF IT SPECIALIST OFFICER CALL 08961556195 OR EMAIL Generators
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