[HN Gopher] Learning basic electronics by building fireflies
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Learning basic electronics by building fireflies
Author : signa11
Score : 146 points
Date : 2025-07-29 17:00 UTC (5 hours ago)
(HTM) web link (a64.in)
(TXT) w3m dump (a64.in)
| Workaccount2 wrote:
| 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.
| jabedude wrote:
| 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?
| roboror wrote:
| Like $2 if you're patient
| alias_neo wrote:
| 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.
| bombela wrote:
| 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.
| Liftyee wrote:
| What toolchain do you use to compile Rust for it? I have
| about had enough of undebuggable random Arduino segfaults.
| alnwlsn wrote:
| 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.
| cluckindan wrote:
| 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...
| bluescrn wrote:
| Search YouTube for '10 cent microcontroller' to learn about
| the absolute cheapest chips.
|
| For PS3.50 you can get an ESP32 module with WiFi and
| Bluetooth (e.g. https://thepihut.com/products/esp32-c3-mini-
| development-boar...)
|
| (A regular Arduino board might still be the best choice if
| you're just learning/tinkering though)
| diggan wrote:
| > 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.
| stevevets wrote:
| "That is not a hair question."
| hobs wrote:
| 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!
| supportengineer wrote:
| 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.
| ourmandave wrote:
| 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.
| AlanYx wrote:
| Do you happen to know of any good modern alternatives to those
| vintage Radio Shack kits?
| macintux wrote:
| You might check out this store that opened recently in rural
| Indiana.
|
| https://tekshack.com/collections/educational
| supportengineer wrote:
| Yes there was one called Snap Circuits that I got for my
| kids.
| morninglight wrote:
| I cannot say enough good things about this store. I've been a
| customer for many years and have never been disappointed. You
| can find things cheaper online, but for a kid without a
| credit card these guys are great. They even have a brick and
| mortar store for local pickup.
|
| https://www.electronics123.com/
|
| https://www.electronics123.com/contactus
| nerdsniper wrote:
| 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.
| BashiBazouk wrote:
| 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...
| xixixao wrote:
| How small could you make this? Could you (maybe not with diy
| tools) make it the size of a firefly?
| bombela wrote:
| 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.
| alnwlsn wrote:
| Much smaller. Definitely smaller than the LED itself.
|
| https://hackaday.com/2025/03/19/worlds-smallest-blinky-now-e...
| behnamoh wrote:
| 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.
| alias_neo wrote:
| 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.
| blackguardx wrote:
| 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.
| bee_rider wrote:
| 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 wrote:
| 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.
| yojo wrote:
| 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 wrote:
| jesus christ
| korse wrote:
| Congratulations, you just independently discovered BEAM robotics.
| alias_neo wrote:
| 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!
| stared wrote:
| > 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-...
| SAI_Peregrinus wrote:
| 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.
| octaane wrote:
| 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 wrote:
| 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.
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