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cadr commented on Raspberry Pi Pico as AM Radio Transmitter   pesfandiar.com/blog/2026/... · Posted by u/pesfandiar
pesfandiar · 10 days ago
Mea culpa.

Without the proper knowledge or measurement equipment, I observed that the audio would fade out after a 30 cm distance. Combined with running it for mere seconds to test and record a demo, I assumed to be in the clear with the spirit of the regulations. Appreciate the reminder to be responsible with RF.

cadr · 10 days ago
I don’t know what the regulations are in your country (looks like you are maybe in Canada?), but in many countries it is straightforward to get an amateur radio license, and then you can have all sorts of fun (under the rules).
cadr commented on Nobody knows how the whole system works   surfingcomplexity.blog/20... · Posted by u/azhenley
agumonkey · a month ago
There's various degrees of understanding, for instance as a web dev, you know the browser, the osi network stack.. (in theory, there are a lot of tweaks) then maybe the electronics.. but the radio / wireless part is another world in itself with a totally different mindset (analog waves) which make the rabbithole way too long (and wide.. radio is a big world on its own)
cadr · a month ago
Amateur radio is pretty approachable and has lots of opportunity to go down those rabbit holes.
cadr commented on Project Patchouli: Open-source electromagnetic drawing tablet hardware   patchouli.readthedocs.io/... · Posted by u/ffin
RossBencina · 2 months ago
> Honestly, just pick up the Art of Electronics

I got this advice in 1998. I have the book. I found it useful for the "art" part. It got me through the projects that I was working on at the time, but personally it didn't help me with the fundamentals. Paraphrasing what has been said on this site many times in the past: AoE is a great first book in practical electronics if you already have an undergraduate degree in physics. I showed my brother AoE when he was building guitar pedals and he couldn't make sense of it and said it was obviously assuming things that he didn't know (he had no high-school science background).

There are a lot of potential and/or assumed pre-requistites even for basic electronics: high school physics, first-year calculus, maybe a differential equations course, certainly familiarity with complex numbers. As I understand it EEs take vector calculus and classical electromagnetism, that's a long road for self-study. For that reason it's hard to give general advice about where to begin.

For someone starting out I think the first things to study are DC and then AC analysis of passive circuits (networks of resistors, capacitors, inductors), starting with networks of resistors. Ohms Law, what current and voltage actually mean, some basic introduction to the physics passive components. This is the basics, and I don't see AoE getting anyone over this hump. This could be learnt in many ways, electronics technicians and amateur radio people know this stuff -- there are no doubt courses outside university both on line and in person. If we're talking books, get a second hand copy of Grob's "Basic Electronics." Once that's covered you can move on to semiconductors. I can recommend Malvino's "Electronic Principles," but this book won't teach you about resistors, capacitors and inductors. After that I think the Art of Electronics would be approachable. And also more specialised topics like digital design or operational amplifier circuits.

A book that usually gets a mention is Paul Scherz "Practical Electronics for Inventors." I got that book later, I personally found it a bit overwhelming with the mixture of really basic practical stuff combined with more advanced circuit theory, but it's no doubt popular for a reason.

Another standard recommendation is to buy one ARRL Handbook from each decade (I have 1988), the older ones have less advanced (hence more accessible) material. But reading the "Electronics Fundamentals" chapter is no substitute for Grob and Malvino.

cadr · 2 months ago
Seconding an old ARRL handbook.
cadr commented on Linux DAW: Help Linux musicians to quickly and easily find the tools they need   linuxdaw.org/... · Posted by u/prmoustache
cadr · 2 months ago
Is there a way I can see which would run on a raspberry pi?
cadr commented on I program on the subway   scd31.com/posts/programmi... · Posted by u/evakhoury
firefax · 3 months ago
I used to get frustated that the train shook so loud that in combination with the sound of the train I struggled to listen to podcasts, kudos to you.
cadr · 3 months ago
I sometimes would bring ear-protection headphones that I'd wear over my earbuds to muffle the train noise.
cadr commented on I program on the subway   scd31.com/posts/programmi... · Posted by u/evakhoury
gozzoo · 3 months ago
That's so cool. Can you share more about this. What program and keyboard did you use? Did you proceed with more serious learning?
cadr · 3 months ago
I used an Akai LPK25 with my iPhone (using the Camera Connection Kit and a combined usb hub/dac) and an app called Simply Piano. They make a wireless version of that now that would simplify the setup a great deal. It is a mini keyboard and the keys are quite small, but in my experience it was fine for the beginner stuff (and the keyboard is useful in general later). As I said before, I stuck with this until the app started using keys outside the range I had.

Now, as for "did I proceed with more serious learning" - I alternate though a ton of hobbies. So I moved on after that, though still go back to it from time to time. But I also have other musical interests and it was helpful to those as well.

Also did a lot of music on the commute on my iPhone with Korg Gadget (and Caustic before that). Sometimes with a keyboard, sometimes without.

cadr commented on I program on the subway   scd31.com/posts/programmi... · Posted by u/evakhoury
cadr · 3 months ago
I used to get so much done on my BART commute. Also learned piano on a little 25 key midi keyboard until the program I was learning from started needing a 26th key.
cadr commented on The true story of the Windows 3.1 'Hot Dog Stand' color scheme   pcgamer.com/software/wind... · Posted by u/naves
cadr · 3 months ago
I'm amused she said they included it "in case somebody out there liked ugly bright red and yellow" and that "the 'Fluorescent' theme was also pretty ugly, but it didn't have a catchy name, so I've never heard anything about it."

Because I loved the Fluorescent theme.

cadr commented on The tiniest yet real telescope I've built   lucassifoni.info/blog/min... · Posted by u/chantepierre
dekhn · 3 months ago
Uh, OK. So a few decades ago a scientist I respect built his own scientific tool from parts (https://www.nature.com/articles/35073680) and I was really blown away by that idea, especially because most scientific tools are very expensive and have lots of proprietary components. I asked around at the time (~2001) and there wasn't a lot of knowledge on how to control stepper motors, assemble rigid frames, etc.

Although my day job is running compute infra, I have a background in biophysics and I figured I could probably do something similar to Joe Derisi, but lacked the knowledge, time, and money to do this either in the lab, or at home. So the project was mostly on the backburner. I got lucky and joined a team at Google a decade ago that did Maker stuff. At some point we set up a CNC machine to automate some wood cutting projects and I realized that the machine could be adapted to be a microscope that can scan large areas (much larger than the field of view of the objective). I took a Shapeoko and replaced the cutting tool with a microscope head (using cheap objectives, cheap lens tube, and cheap camera) and demonstrated it and got some good images and lots of technical feedback.

As I now had more time, money, and knowledge (thanks, Google!) I thought about what I could do to make scientific grade microscopes using 3d printer parts, 3d printing and inexpensive components. There are a lot of challenges, and so I've spent the past decade slowly designing and building my scope, and using it to do "interesting" things.

At the current point, what I have is: an aluminum frame structure using inexpensive extrusion, some 3d printed junction pieces, some JLCPCB-machined aluminum parts for the 2D XY stage, inexpensive off-the-shelf lenses and industrial vision camera, along with a few more adapter pieces, and an LED illuminator. It's about $1000 material, plus far more time in terms of assembly and learning process.

What I can do: the scope easily handles scanning large fields of view (50mm x 50mm) at 10X magnification and assembles the scans into coherent fullsize images (often 100,000x100,000 pixels). It can also integrate a computer vision model trained to identify animacules (specifically tardigrades) and center the sample, allowing for tracking as the tardigrade moves about in a large petri dish. This is of interest to tardigrade scientists who want to build models of tardigrade behavior and turn them into model organisms.

Right now I'm working on a sub-sub-sub-project which is to replace the LED illuminator with a new design that is capable of extremely bright pulses for extremely short durations, which allows me to acquire scans much faster. I am revelling in low-level electronic design and learning the tricks of trade, much of which is "5 minutes of soldering can save $10,000".

I had hoped to make this project into my fulltime job, but the reality is that there is not much demand for stuff like this, and if it does become your job, you typically focus on getting your leadership to give you money to buy an already existing scope designed by experts and using that to make important discoveries (I work in pharma, which does not care about tardigrades).

Eventually- I hope- I will retire and move on to the more challenging nanoscale projects- it turns out that while you can build microscopes that are accurate to microns with off-the-shelf hardware is fairly straightforward, getting to nanoscale involves understanding a lot of what was learned between the 1950s and now about ultra-high-precision, which is much more subtle and expensive.

Here's a sample video of tardigrade tracking- you can see the scope moving the stage to keep the "snout" centered. https://www.youtube.com/watch?v=LYaMFDjC1DQ And another, this is an empty tardigrade shell filled with eggs that are about to hatch, https://www.youtube.com/watch?v=snUQTOCHito with the first baby exiting the old shell at around 10 minutes.

cadr · 3 months ago
Having it automatically follow tardigrades is so cool! It sounds like great fun. Did you make the ML model for tracking them?

I've wanted to make this the Openflexure Microscope (https://openflexure.org/projects/microscope/) but it is behind the backlog of all sorts of other things.

cadr commented on The tiniest yet real telescope I've built   lucassifoni.info/blog/min... · Posted by u/chantepierre
dekhn · 3 months ago
History is made by people who reflabor the exahenge.

I build microscopes instead of telescopes (as a hobby). I can't tell you how many times I've taken a mostly working system and stripped it down to make some important change that affects most of the design to get only a tiny incremental improvement. Sometimes that improvement makes all the difference (for example, being smart when 3d printing a piece that carries something heavy so it doesn't deflect) and sometimes it's just an itch I need to scratch. Eventually, I learned to make two: a microscope that gets built and used, and then a microscope that is a prototype. Then I'm not tempted to take the daily driver and pull the engine.

cadr · 3 months ago
Ooh! Tell us about microscope making as a hobby!

u/cadr

KarmaCake day446September 9, 2009View Original