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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.

I still can't get over the fact that all electronics schematics is actually in reverse and everyone is still fine with that.
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"That is not a hair question."
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!
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.
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...

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

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.
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!"

Congratulations, you just independently discovered BEAM robotics.
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!

> 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-...

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.
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.

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.

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

> 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!)

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.

>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.

This is why I miss Radio Shack. I live in a fairly large city and there’s nowhere local to buy electronic components.
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.
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?
I really loved that you started with a multivibrator scheme instead of arduino