Learning basic electronics by building fireflies
a64.in

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318 points

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signa11

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3 days ago

81 comments

stared ・ 3 days ago

> I love fireflies. But in recent years, they stopped coming for reasons I don’t know. No tiny, glowing dots in the dark like they used to. I miss them more than I expected.

Light pollution, and even more: pesticides.

Population of all insects fall dramatically.

"Three-quarters of flying insects in nature reserves across Germany have vanished in 25 years" - https://www.theguardian.com/environment/2017/oct/18/warning-...

  • rickydroll ・ 3 days ago

    As I understand it, fireflies are vulnerable to lawn chemicals and light pollution. They spend something like 2 years as grubs and then a few weeks as adults above ground. Lawn/in-ground pesticides kill the grubs, and light pollution interferes with finding a mate.

  • SAI_Peregrinus ・ 3 days ago

    Also people removing fallen leaves. They lay their eggs in leaf litter, if there's no leaf litter there won't be any fireflies looking to mate.

  • BobbyTables2 ・ 3 days ago

    I have memories of the front of the car being caked in bugs from night driving and long daytime trips.

    Doesn’t seem to happen anymore…

  • ubermonkey ・ 2 days ago

    30 years ago, when I moved to Houston, a 1910s-1920s residential area called the Heights was somewhat famous for its fireflies -- though longtime residents would tell you they were drastically diminished from what they'd been in the 60s or 70s.

    By 20 years ago, they were almost entirely gone.

Workaccount2 ・ 3 days ago

The juxtaposition between the cleanliness of the software and the absolute travesty of a schematic is jarring. But it still works!

I applaud the author for wading into analog electronics. Pretty much everyone nowadays would just put a timer on a micro and be done in 2 minutes. No fun in that. There is something to be said about the minimal elegance of purely analog designs, and a special rewarding feeling for wrangling electrons in their native habit rather than their boxed up binary bins.

  • diggan ・ 3 days ago

    > Pretty much everyone nowadays

    I think it depends on the ecosystem. It's true much of the "maker" community tends to embrace whatever solution is the cheapest, fastest and easiest to get something working out the door, but on the other hand, the DIY synth community tends to be the opposite (in my experience at least), favoring simple schematics and "back to basics" building, even sometimes going as far as trying to skip any sort of prebuilt ICs.

    • JKCalhoun ・ 3 days ago

      This would include people building guitar pedals.

  • JKCalhoun ・ 3 days ago

    Yeah, for me, analog is the exciting domain — my undiscovered country. I have played with vacuum tubes as well and thoroughly enjoyed it.

    Transistors were, for some reason, seemingly unknowable to me. But I made a kind of "transistor playground" [1] based around Forrest Mims III book [2] and then enjoyed playing with them.

    [1] https://imgur.com/a/dChq4AZ

    [2] https://archive.org/details/forrest-mims-basic-semiconductor...

    Edit: actually, I had forgotten it was a transistor logic playground for I made for creating logic gates with transistors. Based on another Forrest Mims book: https://archive.org/details/engineersmininot00mims

    • zavec ・ 3 days ago

      That looks awesome, nice work! Very clean.

  • jabedude ・ 3 days ago

    I haven't touch anything like this in a good while, how cheap could I get a simple Arduino style chip with a few gpio to drive a yellow LED in 2025?

    • alnwlsn ・ 3 days ago

      For an "official" answer (programmable from Arduino IDE, genuine new chips) you can get an ATTINY202 from DigiKey or Mouser for $0.50 in qty. 1.

    • bombela ・ 3 days ago

      I have a bag of attiny13a that cost me $0.20 per chip. It is fully self contained. Just add a very small capacitor, give it from 2.8V to 5V. And then you program it the way you want. You can even program and debug it via a single pin if you wish.

      At this cost for a hobbyist it's just hard to beat. It can be anything you want it to be in a few lines of code.

      I personally write Rust for it, not Arduino C++, but it would work just the same.

    • alias_neo ・ 3 days ago

      You could grab any Atmega328p or similar DIL on eBay for a couple of quid, maybe less in batches.

      I've got dozens of them in my electronics drawers I don't really use anymore since ESP32 dev boards are so cheap and capable for home projects.

    • andoando ・ 3 days ago

      You can get a bluetooth/wifi enabled microcontroller like a Pi Pico 2 for $5 or a full on computer running linux for $15 (Pi zero 2)

    • the__alchemist ・ 2 days ago

      Buy any dev board that includes an LED. Nordic, ST, Espressif... doesn't matter for something like this.

    • cluckindan ・ 3 days ago

      If you just need it to blink at some interval, get a NE555 for a dime.

      Granted, you can almost get a microcontroller for that price…

      • dgacmu ・ 3 days ago
        ・ 2 more

        You actually can: The Puya PY32 ranges from about $0.08 on up (well, $0.15 if you only want to buy 5, but the cheapest one is $0.0959 in qty 200 and $0.0676 in qty 5000+). ARM Cortex m0 in a 10-pin ESSOP-10 surface mount package: https://lcsc.com/product-detail/Microcontrollers-MCU-MPU-SOC...

        Kind of mind-blowing. 24mhz 32-bit computer for under a dime.

        But you'll learn more about the analog-ish world and not need to deal with SMD if you go the 555 route. And it'll save you power vs the astable monovibrator with NPN transistors.

    • roboror ・ 3 days ago

      Like $2 if you're patient

  • justaj ・ 3 days ago

    I still can't get over the fact that all electronics schematics is actually in reverse and everyone is still fine with that.

    • the__alchemist ・ 2 days ago

      Could you explain? Most of what I work with seems non-directional, except in cases like Diodes and transistors.

  • btbuildem ・ 3 days ago

    Honestly, it's the easiest onramp for people coming from a software background. Analog circuits are HARD, but rewarding. And as you ramp up to various ICs, things start to ~~~ make sense ~~~ in a wonderful way. Oh, and also the battery life!

yojo ・ 3 days ago

Only tangentially related to the enthusiastic circuit hacking: the reason the author stopped seeing living fireflies may be the drastic, worldwide decline in insect populations, with biomass declining in the range of 2-10%/year[0].

https://en.m.wikipedia.org/wiki/Decline_in_insect_population...

  • yapyap ・ 3 days ago

    jesus christ

    • johnisgood ・ 3 days ago

      Funnily enough, I moved to another apartment which is right by the main road (the sound pollution is driving me crazy, not recommended), and now I have an insect problem. Every night I am fighting moths and dragonflies. Never had an issue in my previous apartment. Both are deep in the city, although the current one has more greenery nearby.

bariumbitmap ・ 3 days ago

This post made me feel things. In Phillip K. Dick's "Do Androids Dream of Electric Sheep?", the inspiration for the movie Blade Runner, wild animals have died out due to the after-effects of war and most people can only afford electric animals as pets.

Here the ingenious circuit design and debugging to make an electronic firefly is made all the more poignant by the fact that artificial lighting disrupts firefly reproduction and communication,[0][1] meaning that LED light pollution at night is one of the main reasons firefly populations are declining.

[0] https://doi.org/10.1002/ece3.4557 [1] https://doi.org/10.1098/rsos.220468

supportengineer ・ 3 days ago

I was programming well before I was learned anything about analog electronic circuits. I had the Radio Shack 160-in-one like anyone else and I could follow the directions but I didn't understand what was happening because I was thinking of it as an orderly pipeline, almost like a conveyor belt, where each component was doing a task. It wasn't until college when we studied LRC circuits in physics that it finally clicked for me. What the individual components do by themselves is not very interesting but it's their behavior when you put them together, that the magic happens. Essentially you are creating a vibration, a wave. You are creating a resonating system. Your waves can be in various dimensions like current and voltage. You can adjust the magnitude and frequency of the waves to perform useful tasks.

  • nerdsniper ・ 3 days ago

    I had RadioShack's "ScienceFair"-brand (co-branded with RadioShack) "Advanced Electronics Lab - 300 projects" kit when I was very young. https://www.ebay.com/p/2254341989

    I just found it again yesterday at a very old-school electronics shop. The kind of delightful place packed wall-to-wall & floor-to-ceiling with stuff where each category (test equipment, passive & active components, motors, motor drivers, audio, video, hobby-everything) is either super well organized (passive "jellybean" components) or a giant pile of eclectic offerings stretching across 40 years of technological history (test equipment).

    I bought it for nostalgia, and I might fix it up or even upgrade it to give to my niece when she's old enough. But looking through it confirmed something I'd long suspected:

    1) Things like LRC circuits don't make sense without an oscilloscope. I have one now but REALLY wish I had one as a kid, even a crazy-cheap incredibly low quality one would have been amazing.

    2) The book was VERY poorly written, seemed rushed and minimally thoughtful - there was no real explanation of fundamentals that could be used to drive creativity and exploration. I wish I'd had a book which explained concepts better. I didn't start understanding electronics in any interesting way until I took calculus-based electromagnetic physics in college.

    Using the kit was mainly fun for me to blow up old-school red LED's. It gave me familiarity with electronics schematic symbols, breadboards, and some very basic tinkering. That young childhood familiarity made me much more comfortable around electrical pursuits throughout my life.

  • AlanYx ・ 3 days ago

    Do you happen to know of any good modern alternatives to those vintage Radio Shack kits?

  • ourmandave ・ 3 days ago

    I begged and begged, but never got the 160-in-one. =\

    I did put together a lot of Radio Shack project-in-a-boxes though.

behnamoh ・ 3 days ago

I hold a BSc in electrical engineering and even I still don't fully understand how circuits work, especially the ones that involve transistors. I tried various mental models to think about the "flow" of current/electrons, but nothing works 100% of the time. Maybe that's just how my brain works: I like algorithmic thinking (A → B → C) as opposed to holding the entire circuit in my mind and solving for V or I.

  • blackguardx ・ 3 days ago

    I have a B.S. and M.S in EE. In undergrad, I took a class where we had to solve a different problem using a new analog circuit each week. At first, we could only use BJTs, resistors, and capacitors. Eventually, we made 555 timers from discrete transistors and "unlocked" that IC for future use. At some point we were allowed to use opamps and other ICs as well.

    This class was the hardest class I have ever taken in my life but it really gave me an intuitive understanding of analog electronics that I still have 20 years later.

    I don't there there is any quick substitute for just putting in the work. All these posts about AI learning are the same. The magic isn't AI, but the motivation to learn. The AI might help some folks get more excited about the process, though.

    • dqh ・ 3 days ago

      This sounds incredible and makes me want to go through a similar learning process. I don’t suppose anyone could recommend a book or course along these lines?

  • alias_neo ・ 3 days ago

    I suppose the BEng in Electronic Engineering I did is more in line with this sort of thing. I did Electrical Engineering (BEng) too but that was more power and control, motors, etc, it didn't really crossover much into this territory.

  • the__alchemist ・ 2 days ago

    It's so easy to cheat with your mental model and think in terms of "When I write 0x69 to the GPIO register, LED turns on....

octaane ・ 3 days ago

As an aside, the disappearance of insects is noticeable elsewhere. I'm a big fishing guy, have been my whole life. Many old-timers I know have commented on the lack of insects.

We've all noticed that certain flies and lures have stopped working, or at least, have significantly reduced efficacy. We think it's because for at least several generations (fish have short lifespans), they haven't been exposed to those insects.

  • somerandomdude2 ・ 3 days ago

    I've heard that too. But, from my experience, it's mostly insecticides: people want mosquito-free and flea-free (and ants, roaches etc) yards, and spray/spread poison that kills them. Unfortunately, it kills everything. I cancelled my yard service and noticed that birds started coming back, chasing the food supply. Butterflies cover my lantana, and I see fireflies at night.

    • AuryGlenz ・ 3 days ago

      I live in Minnesota and the struggle is tough. Either my yard is completely unenjoyable for the family due to mosquitoes and deer flies some years or I kill 50 insects that I don’t want for every one that I do.

      I put up deer fly traps every year and that helps, but this year in particular has been awful for both them and mosquitoes. Luckily for the bugs my sprayer is broken and I haven’t had time to fix it.

      I deliberately avoid the place on our property where fireflies are, on the years that I do spray. We really need a better solution.

      Just to be clear, if we go outside right now we instantly have multiple deer flies trying to land on us and bite, which is only a distraction for the mosquitoes. Without swatting I’d probably get a mosquito bite a minute midday or maybe 5-10 a minute at 7pm.

      • goda90 ・ 2 days ago

        You can target mosquitoes more directly with mosquito dunks. It's a block of dehydrated bacteria that produces a toxin believed to only impact the larva of mosquitoes, fungus gnats, and black flies. Basically you make sure all standing water in the area is drained or has a mosquito dunk in it. You can make buckets full of yard debris and water and a mosquito dunk to attract mosquitoes to lay their eggs that then get killed.

        You can also try to increase the number of predators. Create habitats for bats, dragonflies, mosquito larva eating fish, etc.

        I've found picaridin lotion to be much less annoying than DEET spray but still effective this year.

btbuildem ・ 3 days ago

> so I searched the web and found tinkercad.com has a circuit simulator where you can drag and drop all the components and see if and how it works. It worked for simple circuits, but for mine, the astable multivibrator, it didn’t for some reason. I tried falstad.com/circuit; the same thing happened. It also didn’t work. I searched the web for the reason, and I’ve noticed that sometimes these simulators don’t work well for complex circuits.

If anyone knows of a hobby-grade circuit design and simulation software (on macos! or online), I'd be so grateful to have it mentioned. I've tried kicad, diylc, fritzing, and a few other options, and nothing really "works". It's like the minds of people who created these are broken in a certain tragic way that just does not yield itself to making useable software.

The holy grail for me would be something that allows to design the electronic, then spatial aspects of circuits -- from testing the functionality, to making the board (and bonus points for stripboard support!)

  • iaaan ・ 3 days ago

    The naive programmer in me wants to assume, "It can't possibly be that hard to simulate a circuit," and get to work on prototyping my own simulation engine but the fact that this apparently has not ben adequately solved yet gives me pause.

    • bartlettD ・ 2 days ago

      As a practicing EE and naive programmer, It is pretty hard to build a simulation engine for electronics and even harder to build a performant engine. SPICE does this with huge matrices of differential equations and math tricks.

      Theres an interesting article by Mike Engelhardt (author of LTspice) which gives hints on the details of their implementation.

      https://www.analog.com/media/en/technical-documentation/tech...

    • fc417fc802 ・ 2 days ago

      It depends on what level of detail you want the simulation to have. Boolean logic is easy. Analog circuits operating in certain (very limited) domains are straightforward. But - noting that what follows is well out of the realm of my experience - in other domains you have to account for things like RF characteristics and quantum effects in the semiconductors.

      Imagine trying to simulate something that used water in tubes to implement logic, except it's analog logic and there's resonance and some of the joints start leaking when they exceed a certain pressure and etc.

    • tuatoru ・ 2 days ago

      SPICE (simulation program with integrated circuit emphasis) is open-source. As is ngspice, next generation SPICE.

      LT-spice is just a graphical front end to make SPICE easier to use.

      Yeah, analog is hard.

  • Nitor ・ 3 days ago

    For hobby use I have found it best to do circuit design and simulation in different pieces of software. LTspice for simulation and KiCad or EasyEDA for PCB design.

    Fully agree that your mind has to be a particular type of broken to click with all of these. I love LTspice for its simulation tools, for example the ability to vary a component value over time in a transient simulation, but it is a software that fights you at every turn when you try to learn it.

hobs ・ 3 days ago

As a electronics tinkerer just getting started I loved that moment when I first opened up some analog device and just ... recognized everything. A great little writeup!

andreareina ・ 3 days ago

I wonder how much of the simulators not working is due to these circuits taking advantage of parasitics. IIRC the original joule thief circuit doesn't have a capacitor despite one being required for boost circuits; physical components have stray resistance/inductance/capacitance that have real effects on the circuit.

bee_rider ・ 3 days ago

Fireflies flash in response to lights. I wonder if a photoresistor sensitive enough to respond to his “firefly” can be found. Then he could rig it up so his fireflies communicate with each other. And maybe real fireflies as well.

It would have to be pretty danged sensitive I guess.

Extra points if the circuit can be rigged up to respond to changes in brightness, so that it doesn’t constantly trigger in daylight….

  • convolvatron ・ 3 days ago

    I did an art piece at the San Francisco insect zoo, and each firefly has a photodiode. the piece is all mounted in a fairly dark area with some filters over the windows for the bugs. they can see each other blink well enough.

  • ethan_smith ・ 2 days ago

    This is achievable with a simple photoresistor and transistor arrangement - real fireflies actually synchronize this way. Adding a CdS photocell in series with a resistor to the base of your existing trigger transistor would make the circuit flash in response to external light pulses while maintaining its autonomous oscillation.

  • x______________ ・ 2 days ago

    I was thinking along the same lines, create artificial fireflies to attempt and lure others back into the neighborhood..

    But then again, fireflies use their lights to attract mates, and I'm thinking now that their phosphorus-based communication might be more complex than just a randomly emitting diode.

    I can picture it now... "You're into WHAT?!? Nope, I'm out of here!"

alias_neo ・ 3 days ago

This takes me back. I remember learning all of this in high school, some decades ago now.

I distinctly remember the first time I hooked up a 555 timer, then it was decade counters, 741 op amps, logic gates and such, then learning the resistor colour codes and blowing up electrolytic capacitors on the bench supplies for fun.

For my 6th form Electronics project I built an 8-bit ADC, parallel to serial converter, then serial back to parallel and an 8-bit DAC as output all from discreet components and logic ICs.

The first half (input stage) was enough for the top grade, but I enjoyed it so much I spent most of my lunch times in the lab building more and more onto it.

I can feel that joy in OPs post.

I later went on to do my degree in Electronic Engineering.

Thanks for that piece of nostalgia and sharing the fun with us with such a wholesome project!

xixixao ・ 3 days ago

How small could you make this? Could you (maybe not with diy tools) make it the size of a firefly?

  • bombela ・ 3 days ago

    The size of a button cell if you have the patience to solder SMT parts, or make PCBs (at home or ordered). You can also purchase breakout board PCBs designed to adapt SMT (surface mount) chips to DIP (legged parts). You can quite easily use them to solder SMTs on it, cutting traces and bridging others with solder to make your own circuit.

fsckboy ・ 3 days ago

>I love fireflies. But in recent years, they stopped coming for reasons I don’t know.

there were fireflies all over in my childhood, we played with them all the time. but I hadn't seen them in decades. Then one summer there there were... in the heart of New York City of all places. Crazy beautiful.

penguin_booze ・ 3 days ago

If I wanted to restart my on-and-off interest in electronics, is there an online or a physical chain of stores from where I could buy basic components piece meal?

ungreased0675 ・ 3 days ago

This is why I miss Radio Shack. I live in a fairly large city and there’s nowhere local to buy electronic components.

sintezcs ・ 2 days ago

I really loved that you started with a multivibrator scheme instead of arduino

korse ・ 3 days ago

Congratulations, you just independently discovered BEAM robotics.

BashiBazouk ・ 3 days ago

My kid is about to learn a bit of electronics as I plan to replace some PS5 joysticks with TMR replacements. Cracking open without destroying, documenting dissemble so we know where everything goes back and quite a bit of de-soldering, re-soldering. Should be interesting...

I remember in high school signing up for this electronics stuff. I was just learning what a resistor was and a few engineer kids over the two semesters bought and built an original Apple I kit. Ah, growing up in the silicon valley...

stevevets ・ 3 days ago

"That is not a hair question."