Just curious, this is something I know nothing about.
I’m a ham radio operator, and there’s an article that caught my eye about fixing things.
I wondered if it might be relevant to flashlight circuitry.
So here’s a bit from that (it’s paywalled unless you’re an ARRL member)
with some excerpts and a link to the one circuit design program mentioned in the piece (which I find is one of many, has a twitter and a blog and a whole lot of use. Probably there are others as well)
Of interest, perhaps, from the October 2015 QST, publication of the ARRL (ham radio)
Full text only to members; herewith just a brief quote and some links I found to go with it
http://www.nxtbook.com/nxtbooks/arrl/qst_201510/index.php#/66
On fixing things
The article references and quotes Jim Williams … ( … a senior technical resource at Linear Technology, among other companies), from “The Importance of Fixing” — a chapter in his book The Art and Science of Analog Circuit Design
———excerpts follow———
… you actually have to figure out how the circuit was supposed to work, maybe even drawing up a schematic if you don’t have one ….
…. a powerful tool that will never touch the phisical circuit but which can provide valuable insights — the circuit simulator. Recreate the circuit in a simulator like LTSpice and have it compute a DC operating point for you at every point in the circuit. You can then look for significant discrepancies between the simulation voltages and what your meter tells you.
… it’s quite common for an unexpected problem to cause vexing and inscrutable symptoms elsewhere …
“Fast judgments, glitzy explanations, and specious arguments cannot be constumed as ‘creative’ activity or true understanding of the problem. After each ego-inspired lunge or jumped conclusion, you confront the uncompromising reality that the damned thing still doesn’t work …. When it’s finally over, and the box works, and you know why, then the real work begins. You get to try and fix you.”
— J. Williams, The Art and Science of Analog Circuit Design, Butterworth-Heinemann, 1995
———end excerpts ———-