Three Oscillators

This is three quadrature oscillators with the outputs summed together and fed into an oscilloscope in X/Y mode. I'm adjusting the frequency of one oscillator by a small amount.

The crossover distortion of the op-amps I'm using is obvious. They're LM324's. I'm probably going to make a proper etched board for this, using surface mount components and decent op-amps.

My capture card doesn't do the fluidity of the image justice.

Category:

Science & Technology

Tags:

• quadrature
• oscillator
• analog
• analogue
• computer

[jdflyback]

I have tried this but the lm324 can not supply very much current. And my scope has very low impedance so they always make a two milimeter large shape on the scope.hopefully I'll get some transistors and set them in a darlinton configeration so I can finally see something :p

[256byteram]

@jdflyback Weird. Perhaps your oscilloscope is set so the inputs are terminated? 50 ohms is typical.

[vk2zay]

How do the oscillators work? Phase shift with taps to extract the quadrature signals?

[256byteram]

@vk2zay Each oscillator is made of two inverting integrators. If you integrate a sine wave, you get a negative cosine wave and integrating that cosine wave again gives you a sine wave. Close the loop and it oscillates.

[Desmaad]

Why is there a crease in the footage?

[256byteram]

@Desmaad It's the crossover distortion in the amplifiers I'm using, because they're not very good.

[jdflyback]

@256byteram its an oscilloscope i made myself.:)

[FPGAPete]

Very neat.