Circuit a day

Prepared by Dr. Aaron Scher
Oregon Institute of Technology

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Question from the audience: Do you have any advice for people who are interested in walking the path of the poet?

Gary Snyder's response:

Well, yea. First, read a lot of poetry. It doesn't take very long to read virtually all the poetry in the English language. I mean, take it on. If you are going to walk the path, walk the path. And so don't stop with that. Then move on to reading poetry from the other languages in translation. And, you know, try to learn a second or third language as well, so you can see what a different poetic would be in a different language. But in doing that, don't be overwhelmed and keep your own voice. Now that's a good project.

- Lunch Poems with Gary Snyder

Weekly short studies

  1. March 1, 2016 - March 8, 2016: High current fixed voltage regulator, high current fixed voltage regulator with short circuit protection, light controlled switch with CdS cell, more sensitive light controlled switch with CdS cell (screenshot of LTSpice simulation and results here), low-powered tuned resonant frequency AM radio receiver
  2. March 9, 2016 - March 19, 2016: Simple series voltage regulator, improved series regulator, temperature compensated current source, differential amplifier circuit, reflections and review: large signal BJT models, a collection of useful basic BJT configurations for analog electronics design.
  3. March 20, 2016 - April 14, 2016: A collection of basic BJT switches, voltage followers (i.e. emitter followers), current sources, and common emitter amplifiers. Basic current mirror, different ways of analyzing a common emitter amplifier, an equivalent feedback block diagram of a basic common emitter amplifier.
  4. April 5, 2016 - April 13, 2016: BJT RC phase shift oscillator and BJT Colpitts oscillator
  5. April 13, 2016 - April 15, 2016: A study of simple coax-to-dipole antenna transitions and networks.
  6. April 16, 2016 - May 10, 2016: Joule Thief Circuit.
  7. July 31, 2016: Feedback review, Miller effect, Bode stability analysis, Op amp stability analysis and remedies, return ratio stability analysis, common base Colpitt oscillator stability analysis using return ratio, comparison between negative feedback amplifiers and general negative feedback control systems.
  8. August 5, 2016: Foster-Seeley FM Detector
  9. August 16, 2016: Resonant (narrow band) coupling network potpourri!

In-depth studies

Transformers, baluns, signal integrity, EMC, cables, shielding, grounding, protection

  1. Basic transformer
  2. Coaxial cable (shielding and current flow)


  1. Class A small signal BJT common emitter amplifier - voltage divider configuration

Analog Communications Circuits

  1. Fixed attenuators

Power electronics

  1. Basic linear resonant inductive wireless power transfer system
  2. Single diode rectifiers (AC to DC converters utilizing one diode)


  1. DC V-I curves of common components
  2. Series-to-parallel RL and RC transformations
  3. Magnetically coupled coils - equivalent circuits
  4. Positive coupling, negative coupling, and all that
  5. BJT transistor large and small signal models