In this class we will discuss an implementation of the astable multivibrator with operational amplifier that implements a square wave generator based on a Schmitt Trigger and an RC loop, which is also known as a Relaxation Oscillator. We will cover the theory behind astables and how the presented circuit works in each period of operation and produces its square wave. Design equations will be derived to define the duty cycle of the wave and its frequency. We will also discuss how to change the duty cycle so that it does not change the desired frequency. Follow us on Facebook: / elet%c3%b4nica-geral-1038411629625353 Follow us on Instagram: / elt_geral Do you want to learn more about analog electronics? Check out the list of recommended books below and complement your library: 1. Horowitz, The Art of Electronics 3ed (Excellent book with practical circuits. A true handbook, it's expensive but it's beautiful) - https://amzn.to/3iXHA01 2. Sedra, Microelectronics (5ed) (The best analog electronics book in terms of depth and didactics. It's the one I use the most. Content for engineering) - https://amzn.to/303xHH0 ​​3. Sedra, Microelectronics Circuits (5ed - English) (has more exercises than the Brazilian version) - https://amzn.to/3mPwIUg 4. Sedra, Microelectronics (4ed) (cheaper, same content) - https://amzn.to/3crhG2l 5. Boylestad, Electronic Devices and Circuit Theory 8ed (good book, complete, less in-depth than Sedra and cheaper) - https://amzn.to/349w5wD 6. Boylestad, Electronic Devices and Circuit Theory 11ed - https://amzn.to/33Ywce2 7. Malvino, Electronics vol. 1 (Book less in-depth in theory, but with many practical details. Recommended for technical courses) - https://amzn.to/33UYmGN 8. Malvino, Electronics vol. 2 (covers AmpOps and more advanced circuits) - https://amzn.to/349waAr 9. Belongs, Operational Amplifiers and Active Filters (8ed) (great book on AmpOps, straightforward, practical, just the right size. Recommended for technicians and engineers) - https://amzn.to/2FLpal5 10. Platt, Electronics for Makers (Book to learn by doing) - https://amzn.to/32XL7pz ################################################################ Do you know what an Astable Multivibrator is? The astable multivibrator is built as an association of a Schmitt Trigger (bistable multivibrator) and a dynamic feedback loop, such as an RC, RL circuit or an integrator. The circuit has this name because it does not have either of the two stable output levels, that is, the circuit has to periodically change the state of its output and with this it is possible to create a type of oscillator that always generates a square wave at its output. Depending on how the feedback is implemented, another waveform can also be produced along with the square wave, such as triangular and sawtooth waves. Disclamer: An edited version of the video is available on the platforms of the Power Electronics Group of UFMG (https://gep.eng.ufmg.br) and is used as support in the Discipline ELT085 - Analog Electronic Circuits of the Federal University of Minas Gerais. The intellectual property of the video belongs, however, to Prof. Thiago de Oliveira who produced it without the use of UFMG resources.