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Project Patchouli: Open-source electromagnetic drawing tablet hardware

patchouli.readthedocs.io

21–30 of 57 posts

Re: Project Patchouli: Open-source electromagnetic drawing tablet hardware

#21

As a software engineer, seeing hardware projects like this makes me want to go back to school and pick up a few electrical engineering courses. The hardware space just seems to unlock so much (honestly blown away with the LCD retrofit at the end of the video: https://www.youtube.com/watch?v=igVscvWAR1s ) I've played with simple electronics on the arduino and raspberry pi platforms but this is a whole new level. Anyon…

Honestly, just pick up the Art of Electronics - Horowitz and Hill. Spend some time working through that book. By the end of it, you'll have a better grasp of electronics than 90% of the engineers I've worked with, all who are EE bachelors/majors. It's a 3 month job at most, less if you do a dedicated hour a night. Then pick up some breadboard and parts, and build to your hearts content. Making a working circuit is ho…

Note that AoE is not an academic book, more a book for tinkerers.

I'd recommend also to play with https://www.falstad.com/circuit/circuitjs.html

Re: Project Patchouli: Open-source electromagnetic drawing tablet hardware

#24

As a software engineer, seeing hardware projects like this makes me want to go back to school and pick up a few electrical engineering courses. The hardware space just seems to unlock so much (honestly blown away with the LCD retrofit at the end of the video: https://www.youtube.com/watch?v=igVscvWAR1s ) I've played with simple electronics on the arduino and raspberry pi platforms but this is a whole new level. Anyon…

Honestly, just pick up the Art of Electronics - Horowitz and Hill. Spend some time working through that book. By the end of it, you'll have a better grasp of electronics than 90% of the engineers I've worked with, all who are EE bachelors/majors. It's a 3 month job at most, less if you do a dedicated hour a night. Then pick up some breadboard and parts, and build to your hearts content. Making a working circuit is ho…

> 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.

Re: Project Patchouli: Open-source electromagnetic drawing tablet hardware

#27

As a software engineer, seeing hardware projects like this makes me want to go back to school and pick up a few electrical engineering courses. The hardware space just seems to unlock so much (honestly blown away with the LCD retrofit at the end of the video: https://www.youtube.com/watch?v=igVscvWAR1s ) I've played with simple electronics on the arduino and raspberry pi platforms but this is a whole new level. Anyon…

I’m going to go against the standard advice of this book or that course.

Pick up (broken) equipment and start disassembling it to figure out how they turn A into B [1]. Go down the rabbit hole of hunting down the service manual of the thing or one of its siblings. Look at how the pcbs follow the same pattern in competing design. Look at how all the yamaha, sony, medion, … amplifier/tuners are made in the same way and learn from it. Notice that one that is costlier and has those few quircks in its design. Notice how different variations of a theme achieve the same result, but died out because the tech doesn’t scale or simply proved to be suboptimal. Try to repair your broken equipment by understanding the path that the signals and power lines follow.

Rinse and repeat a few years and you’ll get a grasp on what the innards of an unknown electronic thing looks like without opening it. Then open it and be amazed that there was a different, cheaper, simpler way to turn A into B.

All along the way you’ll experience that most educational resources aren’t actually that good at explaining, or that they follow a different school of mathematical notation, or that they’re really good at explaining this detail but the rest is missing.

Design your own pcbs. Remember that - like software - hardware design is iterative. Remember that - unlike software - hardware iterations cost money.

Hope this helps.

[1] the ways to turn A into B are rather limited and it relies heavily on electromagnetism and conservation of energy.

Re: Project Patchouli: Open-source electromagnetic drawing tablet hardware

#28

As an aside, anyone here uses drawing tablets for work? I got a cheap Wacom tablets and found it super useful, for sketching ideas or understanding something before starting to implement new code.

I am doing exactly the same, also writing down some raw ideas I have in it to not forget them.

Re: Project Patchouli: Open-source electromagnetic drawing tablet hardware

#29

As a software engineer, seeing hardware projects like this makes me want to go back to school and pick up a few electrical engineering courses. The hardware space just seems to unlock so much (honestly blown away with the LCD retrofit at the end of the video: https://www.youtube.com/watch?v=igVscvWAR1s ) I've played with simple electronics on the arduino and raspberry pi platforms but this is a whole new level. Anyon…

Forty years ago, I was on my way to college to get a computer engineering degree. I had already been programming in 6502 assembly language and was frustrated that I didn’t understand the hardware side of things as much as I understood the software side of things. Best decision I made. It allowed me to view computation as something more abstract. The barrier between hardware and software processing is artificial and can be moved one way or the other. What is CPU microcode, for instance, hardware or software? It’s really low level software that is typically burned into a ROM but is also sometimes downloaded. Even if you decide to stay with software as your primary day to day job, you’ll be comfortable talking to engineers on the other side of the line and that will help inform your understanding of what’s possible, how much it will cost to design and ship it, how long it will take, and how it will perform.

Re: Project Patchouli: Open-source electromagnetic drawing tablet hardware

#30
post #15

Isn't this technique encumbered by patents? Or have they expired? Anyway I'd be interested in the implementation of a 3D mouse also.

Wacoms key patents did expire which is why there's such strong competition in the tablet space now, and why prices have fallen through the floor.

I wonder why Apple still uses active pens on the iPad when passive EMR has become such a commodity. Maybe it's just rent-seeking, a passive pen would probably be much easier to clone without paying Apples MFi fees.

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