foobag said:http://img840.imageshack.us/img840/3351/capturepak.jpg
is it me or is C, capacitance value supposed to be given for me to find out the frequency of oscillation?
foobag said:ok in that case from my textbook
Fo (frequency of oscillation) = 1/(2R1C1*ln(1+(2R4/R3)) based on the circuit alone without the R2 and zener diode emphasis. My book says that the frequency depends only on the external components and unaffected by Vsaturation.
So my question now is the zener diode voltage that is given is essential in calculating the 2nd part of the question asking for Vamplitude and Vrms for the square wave, am I correct? Or does this affect the frequency of oscillation?
foobag said:i found that Vhysteresis is = +/- (R4/(R4+R3))*Vsaturation
berkeman said:That's not quite right. The Zener clamp comes between the saturated opamp output and the feedback for hysteresis...
foobag said:does that imply I use the zener diode voltages as Vsaturation?
foobag said:well R2 is there to stabilize the zener diode output voltage with its value of 1k, which is considerably less than all of the other resistors
foobag said:so does this answer the part about calculating the hysteresis, and 2nd part of the problem solving for Vamplitude?
berkeman said:Sorry, can you please refresh my memory on what questions you still have left? You know what the output voltage is going to be, and that is the input to the hysteresis voltage divider, right?
foobag said:right, but this time ZD voltage plays a role in calculating the input to the hysteresis voltage divider so Vout = (10/18.7)*7.5 = 4.01 volts amplitude
previously I used the op-amp saturation of 10 volts for the hysteresis. This implies there is no clipping of the square waves generated then, am I correct?
or RMS = 2.836 Volts?
foobag said:I calculated the wrong RMS for a sine wave, for a square wave it is just the amplitude, am I correct, so both RMS and Amplitude are the same for a square wave.
as for the frequency oscillation, my textbook mentions that it depends only on external components, not the saturation voltage/hysteresis. is this wrong?
An astable multivibrator is an electronic circuit that produces a continuous series of pulses without any external input signal. It consists of two amplifying elements (transistors or op-amps) connected in a feedback loop.
The frequency of an astable multivibrator can be calculated using the formula: ƒ = 1.44 / (R1 + 2R2)C, where R1 and R2 are the resistors and C is the capacitor in the circuit. This formula assumes that the transistors or op-amps have equal and symmetrical characteristics.
An astable multivibrator is commonly used as a clock generator in digital circuits, as it produces a continuous series of pulses with a stable frequency. It can also be used in applications such as tone generation, pulse width modulation, and time delay circuits.
The frequency of an astable multivibrator can be adjusted by changing the values of the resistors and capacitor in the circuit. Increasing the values of the resistors or capacitor will decrease the frequency, while decreasing the values will increase the frequency.
The frequency of an astable multivibrator can be affected by the tolerances of the resistors and capacitor used, as well as the temperature and supply voltage. The characteristics of the amplifying elements (transistors or op-amps) can also impact the frequency. Additionally, any external signal or noise can also affect the frequency of the astable multivibrator.