Single-Op-Amp Voltage-Controlled Oscillator (VCO)

In this video we take a simple dual-supply, single-opamp, fixed-frequency oscillator circuit from the Texas Instruments datasheet of the TL082, analyze it with LTSpice, and check the simulations in the real world on a breadboard. We then continue to transform the circuit into a single-supply, low-voltage, voltage-controlled oscillator.
The LTSpice simulations & Excel spreadsheet presented in this video can be found at: www.elektormagazine.com/labs/...
To learn more about opamps and analog electronics in general, try these books:
- Basic Electronics for Beginners: www.elektor.com/basic-electro...
- Electronic Circuits For All: www.elektor.com/electronic-ci...
- The Art of Electronics (3rd edition): www.elektor.com/the-art-of-el...
- The Art and Science of Analog Circuit Design: www.elektor.com/the-art-and-s...
- Robert Lacoste's The Darker Side: www.elektor.com/robert-lacost...

[@davebutler3905]

Well done!!! Nice job.
Short and to the point.
Good explanation of the evolution too.
So much better than all the youtube channels that simply regurgitate text book circuits that they don't really understand and therefore they can't explain.

[@deaddoomed2380]

this video deserves many more likes! amazing work

[@ElektorTV]

Thank you so much 😀

[@ariedemuijnck]

Nice idea for a V to F conversion. I think that for just a voltage to duty cycle converter the circuit just before the diode was introduced would have worked too, and more linear in the V to duty curve.

[@ElektorTV]

Not sure about the better linearity as it is determined by the charging of the capacitor which is non-linear in this circuit. If it is a nice triangle or ramp, then it will be linear. (The usual way of doing PWM.)

[@tHaH4x0r]

As a note, in LTSpice usually adding a very small series resistor (0.1 ohm) with the voltage sources (in this case the two 15V voltage sources) generates enough noise to get oscillators to run as well.

[@ElektorTV]

Tried that too, but it doesn't do it for me in this case.

[@uwezimmermann5427]

I didn't know this, however the trick with an initial condition or injecting a small amount of charge from a pulsed current source always works...

[@magiclay]

do you have some triangle vco?

[@great__success]

Nice explanation ! I am working on simple "sound card voltage logger" i.e. I want to inexpensively log the discharging of lithium 18650 battery by converting the voltage to frequency which will be captured by PC microphone input. Sure, cheap capacity testers are available on aliexpress, but the data logging ability would be great without the need of expensive oscilloscope

[@dailyscienceexperimentsand2761]

Where you are viewing this graph

[@odissey2]

The drawback of such an approach is that the control voltage source has to be low impedance. Thanks anyway.

[@deadlinkofficialartst5592]

my snare drum is about 170hz lol