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- Hacker News
- I have used some regular diodes today as a way to lower the input voltage and this case is not covered. A diode might be more effective than a buck converter because all I wanted was to have a 0.7V lower voltage and the converter can not work in this condition. Zener diode can but it dissipates too much heat for high-current application.by eimrine
- > The diode is given neither the mathematical rigor of linear circuits nor the red-carpet treatment of the transistor
Sedra/Smith dedicates Part I chapter 4 (pages 174-229 in the 7th edition, not counting the exercises) to diodes. That's longer than chapter 5 (MOSFETs) or chapter 6 (BJTs), and a substantial portion of chapter 3 is devoted to pn junctions. "The Art of Electronics" by Horowitz & Hill dedicates less space to diodes, but it's also much less mathematically rigorous. And they have you building radios & diode mixers before they introduce any sort of transistor. So I'm not sure I agree with this line since neither of the two most popular university electronics textbooks really fits that characterization. It's definitely true of many online electronics "tutorials" though.
- The description of forward current and the graph are completely wrong. The graph shows approximately linear current above 600 mV, and the text says "When the threshold is cleared, the diode admits current that’s roughly proportional to the “excess” applied voltage, an ohmic behavior that’s a consequence of the resistance of the material itself".
The current through a diode is exponential with voltage, not "proportional". The graph shows 1.6V applied to a diode yielding 250 mA. In reality, this isn't possible since you'd get a huge current and destroy the diode.
See the Shockley diode equation: https://en.wikipedia.org/wiki/Shockley_diode_equation
I'm surprised that nobody has mentioned that the article is messed up, so am I missing something here?
by kens - Btw you can try these out online with a circuit simulator
- And here's another that's always fascinated me -> Diode Ladder Filter.by djmips
- You can put a small ROM on your board with diodes, for example to store bitmaps, and for style points you can even arrange the diodes in the shape of your bitmaps: https://technologizer.com/2011/12/11/computer-space-and-the-...by sehugg
- You can simulate a bunch of these (and edit too) in your browser in CircuitLab:
Diode half-wave rectifier https://www.circuitlab.com/editor/4da864/
Diode full-wave (bridge) rectifier https://www.circuitlab.com/editor/f6ex5x/
Diode turn-off time https://www.circuitlab.com/editor/fwr26m/
LED with resistor biasing https://www.circuitlab.com/editor/z79rqm/
Zener diode voltage reference https://www.circuitlab.com/editor/7f3ndq/
Charge Pump Voltage Doubler https://www.circuitlab.com/editor/24t6h3ypc4e5/
Diode Cascade Voltage Multiplier https://www.circuitlab.com/editor/mh9d8k/
(note: I wrote the simulation engine)
by compumike - Conspicuously absent are some of the analog circuit applications. Here are three of my favorites:
1. Frequency mixer, used for heterodyning, important in radio, so I hear. https://en.wikipedia.org/wiki/Frequency_mixer
2. Log converter, where the output voltage is proportional to the logarithm of the input voltage. https://electronics.stackexchange.com/questions/374440/log-c...
3. Diode ring, which provides variable gain, used in analog compressors like the Neve 33609 (I have a clone of the 33609, and I’m very fond of it)
Think about this: if you have a nonlinear device like a diode, then the dynamic resistance changes depending on the operating point. If you modulate the operating point, you’re modulating the dynamic resistance.
by dietrichepp