# How do I tell if the Wien bridge oscillator I built works

#### David lopez

I built a wien bridge oscillator. But how do I tell if it works? I am very new to building circuits. I recently
Starting making circuits on a breadboard. I have not taken any
Electronics class. I am trying to learn how to do this.

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#### Baluncore

What frequency do you expect your oscillator to generate?
Please post the circuit you used with component values.
Drag and drop it onto your next post here.

#### scottdave

Homework Helper
• Did you build it from some instructions?
• Do you know what frequency it is supposed to oscillate at?
• Where did you get your circuit diagram?
• Can you show the diagram?

I'm guessing you do not have an oscilloscope. If the target frequency is in the audio range (less than 15000 Hz), you could hook up a small speaker or earphones and perhaps hear the sound. You could download a music tuning app on your phone (like Panotuner or DA tuner) to find out what frequency it is. Or another useful app is from https://phyphox.org/ (Android or IOS).
Spectroid is an Android app to show frequency sound spectrum.

#### David lopez

I followed instructions from the website "how to build wien Bridge oscillator circuit learning about electronics articles". I used two capacitors both have 470 microfarad
And two resistors both have 1000 ohms. And I used an operational amplifier. the equation I used to calculate the expected frequency is
1/2πRC. I calculate 0.3791 hertz. Does that mean you get 1 cycle every 2.64 seconds?

#### Nik_2213

IMHO, you'll be lucky getting that low a frequency to work reliably at first...
In my amateur experience, albeit with '741' op-amps, Wien Bridge oscillators often refused to 'play nice'. A gross mismatch between the R vs C impedances was often the cause. Unrelated but analogous failures abound in 'flip-flop' _-_-_-_- multivibrators when RC pairings are too unbalanced, intended function swamped by 'second order' stuff...

FWIW, trouble-shooting an 'accidental' ELF oscillator can be quite the head-scratcher as an op-amp's vast low-frequency gain may out-flank you...

Try swapping RC components to raise the working frequency to mid-audio 1 kHz ~ 10 kHz range ? A take-off capacitor and a pair of \$1 headphones should suffice to check function. Or, given the capacitor, a budget multimeter on 'AC Volts'.

Get the beast working in mid-range, then work outwards by wary stages.

( I began with soldered strip-board, grabbed my first solderless breadboard, an 'S-Dec', with cries of glee. Got more done in a week using that than in previous six months. Iteration is a powerful, powerful learning tool... )

#### jim hardy

Gold Member
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I built a wien bridge oscillator. But how do I tell if it works?
I calculate 0.3791 hertz. Does that mean you get 1 cycle every 2.64 seconds?
At that low frequency you could put a capacitor and meter in series across the output.
You should see the polarity reverse every $\frac{2.64}{2}$ seconds.

#### berkeman

Mentor
I built a wien bridge oscillator. But how do I tell if it works? I am very new to building circuits. I recently
Starting making circuits on a breadboard. I have not taken any
Electronics class. I am trying to learn how to do this.
Since you are new to learning about electronics and wanting to keep learning more, I'd suggest looking into inexpensive simple USB-based oscilloscopes. That will give you a basic way to see what your circuits are doing, and help you to build more complicated projects in the next year or two.

http://www.bitscope.com/product/BS05/

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