5 Ways To Generate A Sine Wave (Analog)

Sine waves are the fundamental waveform of the universe. Unfortunately, they aren't the easiest to generate in an electronic circuit.

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[justovision]

Side note: Using a light bulb to create a stable sine generator was the idea behind Hewlett Packard's first product and they continued manufacturing them in basically the same form into the 70s. I have a 201c from the early 70s on my shelf that still works well.

[jyoutishmanroychoudhury]

Learned all this in my bachelor's in Electrical Engineering, which was mostly from a theoretical a numerical point of view, but after watching the applications of it and the simple explanation gave a clear understanding of it. Thanks for making this video, keep up the good work!

[francoisleveille]

My method is not in your video. I use a relaxation oscillator - usually based on a 74XX14 Schmitt trigger - then a wave shaper based on 6 diodes, one capacitor and a resistor. You can generate a wide frequency by varying the resistor (potentiometer) on the feedback RC filter of the Schmitt trigger.

[wernerfritsch]

A common way to generate a sine wave used in analog function generators is to generate a triangular wave by switching a current source on a capacitor and then distort the triangular wave to a sine wave with a ladder of diodes and resistors. The THD is not that good (typ. 0.5%), but it is easy to vary the frequency.

[InssiAjaton]

A little note about the original pronounciation of Mr. Wien’s name. It was not “wine”. Maybe closer to English spelling would result from “ween”. Probably useless to try making any change, considering that the name of the city — Wien — is in English world also modified to Vienna… Just my today’s rattle!

[dalenassar]

GREAT VIDEO!

I once made a "variable" sine wave oscillator with a switched-capacitor filter IC. With this filter chip (the mf-10) the output center frequency is determined by a square-wave input. I just varied the square-wave input (10x the output filtered frequency), and got a completly variable sine out, just by varing the input of a 555 timer. This allowed the the output sine frequency and amplitude to be independently varied with an op-amp at the output.
thanks again for the video!!

[martym]

Very informative but fast forwarded. I'll sure pause it after every part and try to understand and test it in my small home lab until I learn it all. Thanks!

[MysticMonster]

Great pace and consice experimental & theoretical explanations. This is a great recap of popular topologies. I am a fan of crystal oscillators personally

[cezarcatalin]

Please make a video about “negative resistance devices”.
You can theoretically make a sine oscillator with just a LC tank circuit and a tunnel diode.
Another device that can work is called a “lambda diode”. It’s basically either two JFETs or a JFET/BJT pair that has a I/V curve looking like a capital lambda symbol.

Speaking of other sine wave generator designs:
1.) Triple inverter hysteresis oscillator making a triangle wave over a capacitor followed by an integrator opamp active filter.
2.) Emitter-Coupled LC Oscillator, which is harder to explain but it’s basically an attenuated LC tank hooked to an “anti-current mirror” differential amp setup made from two NPN BJTs. Since the common emitter pointing in a constant current sink thing makes the opposite BJT do the opposite thing compared to the BJT in which we feed the LC signal, it acts to increase the oscillation with each swing. However, due to the current limiting element and due to dampening, the oscillation stays a clean sine wave. Furthermore, this oscillator is more exact than the Colpitts or the Hartley variants because it only uses one inductive element and one capacitive element. With like 3 resistors, 2 BJTs, an L and a C, this is one of the simplest oscillator designs besides the tunel diode oscillators.
3.) Double active integrator filter inverter loop. Very similar to phase locked loops except you have an active non-inverting filter in series with an active integrator filter. It has 3 resistors, 3 identical capacitors and 3 opamps. One of the resistors on the derivative side of the pid needs to be a few ohms lower than the rest (for stability and to avoid saturation).
4.) Emitter-Coupled Crystal oscillator (yep, there are those too). Same as the one above but the LC + R is replaced with a crystal.

[andrewwhite]

Double integrating a square wave can be used the generate a sine directly. I built a accurate tone generator for a communication system. Xtal oscillator followed by PLL driving 2 op-amp integrators. Output to 600R line driver. Same principle but different implementation, without the frequency drift 🙂

[janpolak]

Interesting channel, I like that you experiment with discreet elements. It has its charm, when I was your age (seventies) there was only such electronics for hobbyists, and this teaches the basics. :)

[thebelectronicsmx]

This video is freking great! Keep it up!!

[Partysize]

This was a very good presentation. Very nice to have the formulas for each circuit.

[marbleop]

Very nice video!
I vaguely remember that it's possible to create sinusoidal signals by feeding two or four integrators into each other, since sine and cosine are derivatives of another.

[WRMD]

You have such great knowledge. Thanks for sharing. Looks like you have a great channel here.

[Graham_Langley]

Other than a tiny tungsten lamp to stabilise the gain of a Wien bridge oscillator it was common to use a vacuum-encapsulated self-heating thermistor designed for that kind of thing - R53 for example - but they're no longer made.

[jagmarc]

I've done every one of these in past when I was a designer. There's quite a few things can do with each circuit that makes the sine purer and output level more stable, but most real applications don't need them. The JFET agc is temperature sensitive output level, can get two orders more stability by using a bandgap reference plus long tail pair

[michaelbuchholz]

I once made a mathematical model of something, i hoped would become a sine generator.
I started with a rectangular wave and fed it into a constant current source. That source is fed into a capacitor.
The resulting wave will be a triangle.
Then, feed that triangle into another constant current source and the output into another capacitor.
The resulting signal is a sine wave.

Well - i never built that. But i wrote a program, that calculates the currents and voltages. It then compared that to a real sine wave. The difference was about 1%, which surprised me a little.

[jamesmorton]

Where is the twin Tee notch ? It provides very low distortion, stability, and simplicity using an OPAMP. Very good presentation.
Check out Analog Devices DDS (direct digital synthesis) for the ultimate in range. Programmed with SPI or I2C. Follow it up with a multiplying DAC for amplitude control.

[nathanjaroszynski]

Thank you. I did all of those a few months ago. I did a joule thief oscillator too. Good fun.