Why Isn't My Relaxation Oscillator Producing a Square Wave in Multisim?

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In summary, the conversation is about simulating a relaxation oscillator and a triangle wave generator in a lab. The speaker is having trouble getting a square wave output and is also stuck on deriving the triangle wave output. They have calculated the period of the square wave and are trying to determine the appropriate values for R and C to achieve a 4 V amplitude for the triangle wave. They have also mentioned using Multisim and an oscilloscope to test their circuit.
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I am doing page 4 of the lab attached, and I am trying to simulate the relaxation oscillator in Figure 2. However, I am not getting a square wave like the lab suggests I should get. I have been able to do the derivation at the bottom of the page.

I have attached my multisim diagram as well as my transient analysis of the probe at the output of the op-amp. What is going on here??

Based on my calculation of the period T, using R=1000 Ω and C = 100 μF, I get a period of .220 seconds, and here the spacing between the ''squares'' (which are not very squarey) is slightly under 4 seconds. It also goes above my rail of 5 V.

I'm also stuck on the derivation on page 6,

Vout = -∫Vin/RC dt and proving that it outputs a triangle wave from a square wave.
 

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  • Lab 5.pdf
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  • 5.1 circuit.pdf
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  • 5.1 transient analysis.pdf
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I have figured out that part about the relaxation oscillator, and my multisim now works. I am on the part about the triangle wave generator (page 7). I have derived the relationship, and now I am stuck making my triangle wave output.

I just took the circuit from the previous slide as my square wave and attached it to the triangle generator, and the oscillator just won't read a triangle.

The question asks to pick values of R and C such that the triangle waveform will have an amplitude of 4 V. I am a bit confused about this part I believe.

I just said that the y-axis is 4, and since f=10, then the time, or x-axis, is 0.1. That means RC = 40. So C = 40/R. Choose R=1000, then C = .04 F.

The supply is 5 V from my relaxation oscillator, so my square wave should be +/- 5V, but the oscilloscope for my triangle generator gives me nothing.
 

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  • 5.2 circuit attempt 1.jpg
    5.2 circuit attempt 1.jpg
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  • 5.1 circuit.jpg
    5.1 circuit.jpg
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FAQ: Why Isn't My Relaxation Oscillator Producing a Square Wave in Multisim?

1. What is a relaxation oscillator in Multisim?

A relaxation oscillator is a type of electronic circuit that produces a periodic waveform with a controlled frequency and amplitude. In Multisim, it is a component that can be used to simulate and analyze the behavior of various electronic circuits.

2. How does a relaxation oscillator work in Multisim?

A relaxation oscillator typically consists of a timing element, such as a capacitor or inductor, and a nonlinear feedback element, such as a transistor or op-amp. In Multisim, the timing element can be represented by a capacitor and the feedback element can be represented by a voltage-controlled switch. The capacitor charges and discharges through the switch, creating a periodic waveform.

3. What are the advantages of using a relaxation oscillator in Multisim?

One advantage of using a relaxation oscillator in Multisim is that it allows for quick and easy simulation of electronic circuits without the need for physical components. It also provides a visual representation of the waveform, making it easier to analyze and understand the behavior of the circuit.

4. What are some common applications of relaxation oscillators in Multisim?

Relaxation oscillators are commonly used in electronic devices such as clocks, timers, and oscillators. In Multisim, they can also be used to simulate the behavior of other electronic circuits, such as filters, oscillators, and pulse generators.

5. Are there any limitations to using relaxation oscillators in Multisim?

One limitation of using relaxation oscillators in Multisim is that they may not accurately represent the behavior of real-life circuits due to the simplifications and assumptions made in the simulation. It is important to validate the results obtained from Multisim with real-world experiments.

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