John,
The depth and breadth of your knowledge is fascinating. I first replied to a comment of yours here years ago about Nagle's Algorithm.
I've gotten deep into EE lately so this is very helpful to me as well. I didn't even realize who wrote it until I saw the GitHub username.
Just wanted to say thanks for sharing the wisdom.
Thank you and appreciate your pointing me to a project that i can learn from. While i agree that modern-day PCBs often have their magic inside an FPGA/ASIC/MCU, the overall system is still defined by the PCB. If something doesn't work and i suspect the problem isn't in the software, then i should still be able to understand the schematic and follow the signals in the PCB at appropriate points to debug the problem. While there are lots of "hardware hacking" info, i can see no systematic approach to the problem. Perhaps with more study and practice i will learn to identify the key areas to look for and understand.
I would wholeheartedly second 'The Art of Electronics'---it is a perfect book to start with. I would add 'The art of designing analog chips' by Camenzind (the inventor of the 555 timer) and 'Multistage Transistor Circuits' (SEEC, vl 5). The last book is a good introduction into the design portion of the process. If one feels particularly adventurous, reading old Bob Pease's columns in ED is also educational.
Re:How to Read a Schematic
by brianpgordon on Friday April 26, 2019 @09:08PM
(#19763095)
I'm tinkering with electronics and am finding The Art of Electronics very good. At the same time, I'm going through "Practical Electronics for Inventors" - for non-advanced topics it basically covers the same information as The Art of Electronics but in more of an informal/intuitive style than even the decidedly informal Art.
I found "Designing Embedded Hardware by John Catsoulis" quite good in addition to the above two.
So cool: I have a pet project where I hope to use a Type 28 reperforator and had your repo starred for this. Small world.
You don't need that for a Model 28; it only needs 20mA, and you can still buy 20mA current loop interfaces. It's the 60mA machines, where the current loop directly powers the selector magnet, that need this.
For modern commercial products, mostly you'll have some big special purpose ICs plus some minor components for power and noise management. The schematic won't tell you much because all the action is inside the ICs.
Here's something of mine you can look at, a design on Github made with KiCAD.[1] The schematic is here.[2] All the files to make a board are there, and both I and others have had working boards fabbed from those files.
The application is unusual - it's an interface for antique Teletype machines that need signals of 60mA at 120V. There are no off the shelf ICs for that. So there's a custom switching power supply to make that voltage from a 5V USB port. The README file for the project explains how it all works. It has all the extra parts you need in the real world to handle USB hot-plugging, keep the switcher noise out of the USB connection, keep RF noise down, and protect the circuit against a shorted output or a big inductive kick-back from the load.
The data sheet for the LT3750, the controller for the switching power supply, is essential when reading the schematic.[3]
You can download KiCAD and play with the files. You can also download LTSpice and run a simulation; the files for that are in the repository.
This is complex enough to be non-trivial, yet simple enough to be understandable.
[1] https://github.com/John-Nagle/ttyloopdriver [2] https://raw.githubusercontent.com/John-Nagle/ttyloopdriver/m... [3] https://www.analog.com/media/en/technical-documentation/data...