7 ms·
Things you can do with diodes
- jagged-chisel 1y ago> ... There is a positive charge on the n-side and a negative charge on the p-side. How completely unintuitive.
- Shellban 1y agoYou can blame Benjamin Franklin for that. By the time we figured out the mistake, the standards were set in stone.
- dietrichepp 1y agoIt would be like this either way. The N side has negative charge carriers. It has a positive charge in the depletion region because the charge carriers are missing. Likewise, the P side has positive charge carriers, and when they’re missing, you get a negative charge. This is true whether we live in the current universe or live in an alternate universe where we say that electrons have positive charge. The depletion region is where the charge carriers are missing (depleted), so you get the opposite charge of whatever the charge carriers are.
- dietrichepp 1y agoConspicuously 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 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-converter-circuit 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.
- hshdhdhehd 1y agoFrom my hobbying decades ago there is also the boring old rectifier to convert AC to a wavy DC.
- deleted 1y ago[deleted]
- kennywinker 1y agoThose are covered in the article
- nomel 1y ago4. Varactors! https://en.wikipedia.org/wiki/Varicap https://en.wikipedia.org/wiki/Varicap Reverse biasing a diode at different levels changes the junction capacitance. Also used in radio, for things like variable filters. edit: oh, it's topped pinned comment!
- bob1029 1y agoZener diodes can be used as the basis for a quantum random number generator. https://opg.optica.org/optcon/fulltext.cfm?uri=optcon-1-7-1572 https://opg.optica.org/optcon/fulltext.cfm?uri=optcon-1-7-15...
- phkahler 1y agoThese are also good noise sources and were use in several early video arcade games for producing explosion and spaceship thrust sounds. https://en.wikipedia.org/wiki/Noise_generator https://en.wikipedia.org/wiki/Noise_generator
- beckler 1y agoKinda interesting to hear about. I have a 500 chassis I’m slowly working on filling. I’m between the RND 535 or 543, and had never heard of a diode bridge comp before looking at the 535. What kind of 33609 clone do you have?
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- hshdhdhehd 1y agoCurrent/voltage chart looks a lot like a RELU.
- CamperBob2 1y agoThat's exactly why it's called a 'rectified' linear unit! It's a half-wave rectifier. The ReLU function is just what you'd see if you put an (ideal) diode on a curve tracer.
- CamperBob2 1y ago(Although to be more accurate, it would be what you'd see on an I-V curve tracer if you measured an ideal diode in series with a 1-ohm resistor. The diode by itself would just go vertical at the Y axis, and the ML people would mutter into their beards about exploding gradients.)
- hshdhdhehd 1y agoAnd that diode would be an exploding grenadiant?
- CamperBob2 1y agoYes, because the slope of current versus voltage goes infinite as soon as the voltage goes positive. The math would explode, and so would the diode, given enough current.
- Cymen 1y agoAlso missing solar heating from diodes: > This topic seems to be broadly misunderstood. It is 100% verified fact by both myself and others (including university researchers) that diode strings can produce more heat (or watt-hours, BTU) from a given solar panel than a bare resistance element. https://www.youtube.com/watch?v=42XIbHA9Dv0 https://www.youtube.com/watch?v=42XIbHA9Dv0
- Retr0id 1y agoIntriguing, but wouldn't it be even more efficient to just paint something black and let the sun heat it directly?
- Scoundreller 1y agodepends how hot you want to get something
- cwillu 1y agoAt the cost of very efficiently radiating that heat back out into space at night. Making electricity and then using that electricity to heat something elsewhere lets you insulate, effectively allowing you to create a box that heat energy can only pass one way.
- jaggederest 1y agoWe have a one-way diode technology for heat, it's called "glass", and it'll bump your efficiency by about 25% versus uncovered flat plates on a still day. More in windy conditions etc, lots of hand waving assumptions about spherical cows in a vacuum etc.
- b00ty4breakfast 1y agoYou'd need some kind of storage for the heat, something with a large thermal mass that doesn't readily give up it's heat to the surroundings. Sand or water or even big rocks or a thick slab of concrete.
- petermcneeley 1y ago
- wormius 1y agoI know we're on hacker news, but let's just say I misread the title.
- deleted 1y ago[deleted]
- uticus 1y ago> The reason I put “gate” in scare quotes in the illustration is that the circuits are not readily composable to implement more complex digital logic... Any good suggestions on resources talking about building complex digital logic out of something more suitable?
- JKCalhoun 1y agoThey might be referring to RTL (resistor-transistor logic). A transistor in the circuit can maintain the same output current that was input. (A transistor in fact a diode and a half.) RTL was superseded by TTL (transistor-transistor logic) but, hey, the Apollo computers that put astronauts on the Moon used RTL logic. You could start with the late Don Lancster's book [1]. I have a little "breadboard helper" that I am wrapping up (that includes a project manual) for creating RTL circuits and others [2]. (I hope to sell a few.) RTL book [1]: https://archive.org/details/RTL_Resistor-Transistor_Logic_Cookbook/ https://archive.org/details/RTL_Resistor-Transistor_Logic_Co... Prototyping [2]: https://cdn.bsky.app/img/feed_fullsize/plain/did:plc:oxjqlammq27la2ojzsaev7vy/bafkreible7kbs7iieskv2vplcbtdkkkcy2iicvhuzmy72mqmnm5lnikxye@jpeg https://cdn.bsky.app/img/feed_fullsize/plain/did:plc:oxjqlam...
- cwillu 1y agohttps://en.wikipedia.org/wiki/Logic_family https://en.wikipedia.org/wiki/Logic_family has a list of common families; of particular note is CMOS, which is essentially what modern computing is based on.
- _whiteCaps_ 1y agoBebop To The Boolean Boogie might be useful for you - it's kind of a kids book but the concepts are all well done.
- Tuna-Fish 1y agoWhile diodes alone are not suitable for complex logic, they were instrumental on making computers cheaper in the late vacuum tube era. Vacuum tubes have fairly low reliability and short usable life so having too many of them in your computer is really bad for the cost and reliability of your system. Early transistors were not much better. They would get better over time, but cheap, reliable mass produced diodes were available long before transistors got there. And while diodes alone cannot do it, a system with a few vacuum tubes to provide the gain and driving a whole lot of diodes made a lot of computers possible at price points that vacuum tubes alone could only dream of. An example is the hacker folklore sweetheart LGP-30, of The Story of Mel fame. 113 vacuum tubes driving 1500 diodes made for a computer that was the size of a fridge, weighed 800 pounds, drew 1.5kW and cost $50k (~500k in modern money), which made it pretty much a personal computer for the late 50's.
- brucehoult 1y agoHe mentions diode logic and points out the drawback of the limited output current, but doesn't mention the obvious solution of a transistor in voltage-follower configuration. I always thought RTL was pretty nifty, and it was used in a lot of early computers. I think it's a lot less fussy of component values than the earlier RTL.
- djmips 1y agoAnd here's another that's always fascinated me -> Diode Ladder Filter. https://www.youtube.com/watch?v=jvNNgUl3al0 https://www.youtube.com/watch?v=jvNNgUl3al0
- iainctduncan 1y agoDiode ladder filters are a mainstay of old analogue synths... and sound awesome.
- youngtaff 1y agoThey certainly do… I’ve few in my Eurorack synth
- skopje 1y agoforgot adc converter! series diodes tapped at each connection.
- kazinator 1y agoAnother one: Baker clamp to speed up a transistor. https://en.wikipedia.org/wiki/Baker_clamp https://en.wikipedia.org/wiki/Baker_clamp Flyback diode: https://en.wikipedia.org/wiki/Flyback_diode https://en.wikipedia.org/wiki/Flyback_diode A diode can switch off an AC source when a battery is present: see second circuit in accepted answer, introduced by, "Alternatively, you can probably get away with just using some schottky diodes:" https://electronics.stackexchange.com/questions/71753/whats-a-simpler-way-to-switch-between-power-sources https://electronics.stackexchange.com/questions/71753/whats-... Also, diodes can be used to provide a controlled discharge path for capacitors when a device is turned off. The circuit in this EE StackExchange question shows it: https://electronics.stackexchange.com/questions/471285/capacitor-diode-circuit https://electronics.stackexchange.com/questions/471285/capac... It has one RC constant when charging and a different RC constant when discharging through the diode. Why would you want to charge a capacitor slowly when power is applied to the device, but discharge it fast when power is cut? There are various applications for that. For instance, circuits that control some timed behavior, like holding a CPU chip in a reset state at start up while power stabilizes, and then releasing it. You want that circuit to reset itself quickly if power is lost. Analog circuits have things like that in them: for instance circuits that mute an audio amplifier on power up for a bunch of milliseconds until a capacitor charges. If the power is cycled, you want that timer to reset itself. Another application: Log amp: https://en.wikipedia.org/wiki/Log_amplifier https://en.wikipedia.org/wiki/Log_amplifier This exploits the diode's characteristic V-I exponential curve in amplifier feedback to produce output proportional to the logarithm of the input.
- sehugg 1y agoYou 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-dawn-of-the-arcade-video-game/2/ https://technologizer.com/2011/12/11/computer-space-and-the-...
- deleted 1y ago[deleted]
- zh3 1y agoIn some early computers, the bootstrap was actually a matrix of diodes where you'd remove a diode to get a one and leave it in for a zero. I had a bunch of these boards sometime in the mid 1970's and found you could program a fully populated board with a 9V battery - basically connect it across a diode in a bit position where you wanted a '1', there would be a small but pretty flash from inside the glass case as a zero turned into a one. When things like the 74S188 were available, we had so much fun squeezing bootstrap code for PDP11's into 2 of them; 32 words by 16 bits was more than enough (later I got code that would boot five different devices into 256 words).
- ada1981 1y ago[flagged]
- petermcneeley 1y agoBtw you can try these out online with a circuit simulator https://www.falstad.com/circuit/circuitjs.html https://www.falstad.com/circuit/circuitjs.html
- atan2 1y agoNice timing. I just saw pikuma's email with his new course on digital electronics and saw this here.
- iainctduncan 1y agoI'ma just leave this bad boy here.... https://www.youtube.com/watch?v=xNF891FVC6M https://www.youtube.com/watch?v=xNF891FVC6M AJH Synth Sonic V Diode Ladder Filter. (IMHO AJH make the best eurorack filters out there..)
- mitthrowaway2 1y agoYou can extend the voltage doubler idea to even higher voltages with the voltage multiplier: https://en.wikipedia.org/wiki/Voltage_multiplier https://en.wikipedia.org/wiki/Voltage_multiplier
- WorldPeas 1y agoor.. detecting a nuclear event? https://www.alldatasheet.com/datasheet-pdf/view/124266/MAXWELL/HSN-1000.html https://www.alldatasheet.com/datasheet-pdf/view/124266/MAXWE...
- compumike 1y agoYou can simulate a bunch of these (and edit too) in your browser in CircuitLab: Diode half-wave rectifier https://www.circuitlab.com/editor/4da864/ https://www.circuitlab.com/editor/4da864/ Diode full-wave (bridge) rectifier https://www.circuitlab.com/editor/f6ex5x/ https://www.circuitlab.com/editor/f6ex5x/ Diode turn-off time https://www.circuitlab.com/editor/fwr26m/ https://www.circuitlab.com/editor/fwr26m/ LED with resistor biasing https://www.circuitlab.com/editor/z79rqm/ https://www.circuitlab.com/editor/z79rqm/ Zener diode voltage reference https://www.circuitlab.com/editor/7f3ndq/ https://www.circuitlab.com/editor/7f3ndq/ Charge Pump Voltage Doubler https://www.circuitlab.com/editor/24t6h3ypc4e5/ https://www.circuitlab.com/editor/24t6h3ypc4e5/ Diode Cascade Voltage Multiplier https://www.circuitlab.com/editor/mh9d8k/ https://www.circuitlab.com/editor/mh9d8k/ (note: I wrote the simulation engine)
- dr_kiszonka 1y agoLooks great! Would you have a recommendation for intro materials to help me learn the basics of electronics using CircuitLab? I have a working understanding of signal processing but building an actual circuit without electrocuting myself, not setting my Raspberry Pi on fire, or selecting the right set of components for the simplest DIY project based on spec sheets are a mystery to me.
- compumike 1y agoNot sure if it’s a fit for what you’re looking for, but maybe https://ultimateelectronicsbook.com/ https://ultimateelectronicsbook.com/ (maybe more theoretical than practical). I’ve heard good things about “Practical Electronics for Inventors” but haven’t gone through it myself.
- MisterTea 1y ago> Diode Cascade Voltage Multiplier A favorite of mine and one of the most common ways to generate a pretty high voltage DC. The full wave version pairs well with a center tapped secondary of a resonant transformer.
- blankx32 1y agoLectenna / Rectenna https://en.wikipedia.org/wiki/Rectenna https://en.wikipedia.org/wiki/Rectenna
- mattclarkdotnet 1y agoThis is excellent but in typical low voltage scenarios (5V or lower) the 600mV diode voltage drop becomes very significant. Simple diode half wave rectification works fine at 100V, but at 3.3V it breaks down.
- xxs 1y agoat that point (and in general) you'd like to use Schottky ones. MOSFETs are an option for low extra efficiency.
- tiniuclx 1y agoYou can also build a rectifier with no voltage drop using an op-amp with some diodes in the feedback loop. But that might be considered cheating :)
- jotux 1y agoFor low voltage diodes you can use mosfets to get ultra low voltage drop, or just buy dedicated "ideal diode" components that are specifically for that: https://www.analog.com/media/en/technical-documentation/data-sheets/max40203.pdf https://www.analog.com/media/en/technical-documentation/data...
- TrackerFF 1y agoIf you’re into audio, they can easily be used for distortion. You “clip” the top of the audio wave. Usually in a asymmetrical way, to get more pleasant sounding distortion.
- tuggi 1y agoAlso the octaver… https://www.geocities.ws/diygescorp/diodeoctaveup.gif https://www.geocities.ws/diygescorp/diodeoctaveup.gif
- eimrine 1y agoI 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.
- sanskarix 1y ago[dead]
- wkjagt 1y agoInteresting coincidence. I should receive a bunch of diodes from digikey today to fix the bridge rectifier on the control board of our pool heater.
- jamesnorden 1y agoYou can also use a bunch in series as a cheap voltage dropper (eg to make a PC fan run slower/quieter).
- speff 1y agoIs (like the article said) this information really not taught in electronics curriculum anymore? It's been a while since I was in school, but this was all covered in my undergrad EE 2XX/3XX classes. Do modern designs use fewer diodes and more ICs in their place?
- stephen_g 1y agoI’m sure it is still taught, but a lot of power designs do often now swap diodes out for actively controlled mosfets, for example in power multiplexing (there are integrated chips called ‘ideal diodes’ or eFuses which use mosfets that do it all for you), or swapping the diodes in DC/DC converters with mosfets (called ‘synchronous rectification’).
- speff 1y agoExciting! I've been out of the field for a while - thank you for what'll be some interesting reading
- ToddWBurgess 1y agoThis article reads like study notes for the Canadian Advanced ham license exam. It's a great crash course on diodes.
- howmayiannoyyou 1y agoI misread the title at first and forwarded this to my wife.
- ee99ee 1y agoI'll be honest. I misread the title as "Things you can do with dildos"
- AbstractH24 1y agoAnd good for you for saying outloud what many other people also experienced
- kps 1y agoWait 'til you hear about vibe coding.
- uvaursi 1y ago> The diode might be the most neglected component in the electronics curriculum today. Nonsense like this is why I don’t read lcamtuf. His “electronics 100” falls short of any standard-issue books - today and in the past. And you can open any of them up and very often the very first thing they discuss is the Diode, not only because it’s an “easy” case to begin understanding semiconductor materials (as opposed to tube diodes), but because it forms the basis of understanding more complicated semiconductor devices and why they work the way they work. I’ve been wholly unimpressed by lcamtuf’s output on this subject because he’s trying to teach but doesn’t know how. He’s trying to come across as smart but his covering of the subject matter is dwarfed by someone like Forrest Mims, which is amusing to think about. Pick up a book by someone like Melvino or Floyd. They cover analog, digital, computer systems, all sorts of shit. Even the old NEETS books along with technician manuals are a godsend. NEETS approach is particularly good because it moves between phenomena and application in a broad spectrum, which is what helps for concepts to stick.
- kens 1y agoThe 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 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?
- manwe150 1y agoThe Wikipedia equation there mentions the formula ignores the contribution of the internal resistance, which would make it proportional. It seems the article assumes that resistance is a significant contribution (possibly even just from their voltage source) while you assume it is not, for any given particular diode being evaluated or measured, either could be right
- bombela 1y agoWikipedia says: > Internal resistance causes "leveling off" of a real diode's I–V curve at high forward bias. The Shockley equation doesn't model this, but adding a resistance in series will. For small diodes and all LEDs as far as I know, it will level alright. Leaving behind a cute little smoldering crater where the now vaporized diode used to be. https://www.onsemi.com/download/data-sheet/pdf/1n4001-d.pdf https://www.onsemi.com/download/data-sheet/pdf/1n4001-d.pdf Take this very generic diode here. When mounted as instructed for the highest heat dissipation, it should gain 50°C per Watt. The flattening of the Current-Voltage curves starts at around 1A. As the diode heats up, the resistance lowers. Extending the limits. Maximum before damage is 150°C. Minus 25°C ambient leaves us 125°C. Divided by 50°C/W gives us 2.5W. Around 2.8A-3A at 0.8V-0.9V forward voltage. But the curve is barely proportional at 5A. You might also notice that the datasheet doesn't provide numbers beyond that point. Presumably because the diode left the room then.
- SAI_Peregrinus 1y ago> 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.
- uvaursi 1y agoThank you. I was on the fence posting my comment earlier but I’m glad I’m not the only one who is tired of blog posters leading a subject with a blatantly false statement.
- shevy-java 1y agoBack in the oldschool days in the 1990s, I remember our school had soldered diodes, that is, we pupils had to do so manually. That was quite fun. Unfortunately I haven't quite had a need or use case to do so again; I tried to get into arduino, but I found it too much needing self-learning. With that I mean I'd have to understand a lot in order to do something useful. I have no problem with learning something new, but my time is super-limited these days and I need to prioritize hard, so I kind of gave up. Perhaps I try for Raspberry Pi but I am afraid it will also require a lot of time investment before it becomes "useful" (aside from learning something new, which is always useful, but other things also need to be learned, so time is of limited value here).
- hinkley 1y agoI had a friend in high school who brought in the Tesla coil he made with among other things a PSU from an old computer. I pestered that kid so hard about DC-DC voltage regulators and he did not know enough electronics to design one from first principles. I think ladder circuits was as far as he got. But I wanted step-down not step-up transformers. 15 years later when the first gen of really good LED flashlights with built-in voltage regulators popped up I owned at least one at all times.
- lightedman 1y agoNot present and ultimately-cursed - using LEDs not only as bridge rectifier but also as the voltage drop for power conditioning before going into a processing IC. I'm not called the LED Punisher without reason!
- monicanilo274 1y ago[flagged]
- jimmygo 1y ago[dead]
- airbreather 1y agobefore silicon, rectification was often achieved with copper oxide
- dogman1050 1y agoI've been looking for something to do with the bag of 1N4001 diodes I trash-picked decades ago. There are 1,000 pieces minus the dozen or so I've used in projects. The 50V PIV and slow switching speed limits their application, but I have a lifetime supply!