# Tag Info

Accepted

### Why spectrum analyzer ruined my oscillator's output?

Your spectrum analyzer has a 50 Ω input impedance, so it is loading the circuit and changing its behavior, unlike the oscilloscope probe which has a very high input impedance (intended to minimize ...
• 7,524
Accepted

### Wien Bridge Oscillator: Why does equating the real part to 0 give the gain equation?

Because they're starting with the Barkhausen Criterion; loop gain = 1. The loop gain is $$\left( 1 + \frac{R_3}{R_4} \right)\left(\frac{RC s}{(RC s)^2 + 3RCs + 1} \right)$$. Everything else comes ...
• 46.2k

### Why doesn't this Wien Bridge oscillator work?

Firstly, you are trying to produce a bipolar output from a single positive supply. You need to either provide a bipolar supply or create a decoupled virtual ground at 12 V (i.e. half the supply rail) ...
• 4,218
Accepted

### Sinusoidal waveform generator from DC

Any sinusoidal oscillator generates a sine wave from a DC input. That's what oscillators do. (Though not all oscillators generate sine waves - many of them generate different types of waves) The ...
• 12.5k
Accepted

### Wien Bridge Oscillator using OpAmp(LM386) works in simulation, but doesn't work in Breadboard?

The LM386 is not an op-amp, it is a speaker amplifier chip. So it does not work in a circuit that is built around an op-amp.
• 148k

### What is the purpose of the anti-parallel diodes in this Wien Bridge oscilator circuit?

The purpose of anti-parallel diodes in a Wien bridge oscillator is to provide non-linear feedback. For stable oscillator operation, the closed-loop gain must be 1. If it is greater than 1, the ...
• 23.5k

### My Wien bridge oscillator doesn't work, what could the problem be?

As @horta suggested, use wires when needed and "see" the "dot" connection. You should see something like this (distorted.) If oscillation does not start (R3 < = 21k,) make this ...
• 13.2k

### Wien bridge oscillator amplitude stability methods

Any low-voltage, low-power incandescent bulb can be made to work. The trouble, in 2019, is finding them -- LED's just work so spectacularly better for making light from battery power, you'll need to ...
• 46.2k

### The Wien Bridge Oscillator

Here is the block diagram of the iconic HP 204C oscillator: As you can see, it uses a ganged air variable capacitor as the primary tuning elements. A pot is used to adjust the amplitude as ...
• 398k
Accepted

### Is the Wien Bridge oscillator essentially a resonant filter?

Before Johnson noise ever kicks a Wien bridge into action, the sheer monstrous transient of applying power does the job. Some schematics show a Wien bridge oscillator using a tungsten lamp as a ...
• 457k
Accepted

### Wien bridge oscillator circuit doesn't work

You are using your op amp in a single-supply configuration without providing a virtual ground. The simplest fix is to get another 14 volt supply, and connect this as a negative supply to pin 4. If you'...
• 60.5k

### Great Voltage Stable Oscillator

At such a low frequency (2 kHz), you can generate the sine wave by streaming values into a D/A. 256 samples per cycle only requires 512 kHz sample rate, which is quite easily doable. The harmonic ...
• 313k

### Make old telephone ring

The capacitor and ringing coil forms an LC resonant tank. The coil is very high impedance, so when you connect the coil directly, it will not draw enough current to actually ring the bell. When you ...
• 28.5k

### Wien Bridge Oscillator: Why does equating the real part to 0 give the gain equation?

gbmhunter, you have explicitely shown the "WIEN-Robinson" bridge (heart of the WIEN oscillator). Another view of the same circuit sometimes helps to understand the principle better (in ...
• 26.8k

### Frequency of square wave generated by Wien bridge oscillator

Its not a Wien bridge oscillator anymore when you increase the gain - its a relaxation oscillator. The frequency will still be determined by R3, R4, C1 and C2 but in a different manner to that in the ...
• 33.2k

### Why doesn't this Wien Bridge oscillator work?

This question has come up many times. I was curious so I built one two years ago. You need a bi-polar supply, as already mentioned. Why are you using a high-power opamp? Have you tried a normal opamp? ...
• 16k

### Wien Bridge Oscillator with LM358

1) Sorry to be the bearer of bad tidings, but running a 358 at more than about 10 kHz is a losing proposition. The data sheet show figure 7 (page 10) shows maximum voltage swing vs frequency, and you ...
• 60.5k
Accepted

### JFET Burn Out in Wien Bridge Oscillator

From the schematic, I thought that the 25 V JFET should be fine since the greatest possible potential over it would be only 16 V. Not actually, it might be much larger. In the following, for sake of ...
• 5,357

### Wien bridge oscillator amplitude stability methods

Search a bit harder. It's not hard to find bulbs such as the 28VDC 1819 which are stocked by distributors such as Digikey (where the photo of the CM1819 came from - 3,500+ in stock). Of course you ...
• 398k

### Whats the equation to calculate the Vo-w and Vp amplitude of this Wien Bridge oscillator?

There is not an equation as you mean it. In the case of your circuit, the non-inverting gain will be about 3.2, so the amplitude of the output will increase without limit - until it hits a limit. In ...
• 60.5k

### Dual op-amp Wien bridge oscillator queries

This is not a Wien bridge oscillator, though it's trying a bit to look like one. I've redrawn it slightly, to emphasise the 'Wien' components R6, C2 in series and C1 and R1 in parallel to ground. This ...
• 166k

### Frequency of square wave generated by Wien bridge oscillator

Because when you have gain higher than 3V/V, you get faster transitions. With faster transistion, you get a square wave rather than a sine wave. With a square wave, the capacitors in the relaxation ...
• 4,098
Accepted

### Frequency of square wave generated by Wien bridge oscillator

I don't think that the circuit can be seen as a relaxation oscillator. For a relaxation mode, the active device switches abruptly between charging and discharging a capacitor. It is still a Wien-type ...
• 26.8k