My comments are those of a relatively new “newb” - i.e., someone that realizes they are a newb and is just forming longer term thoughts about their status as a newb. There is a lot of great advice on this forum, but for me some of the wisdom in that advice was only apparent in hindsight. I can’t contribute to that wisdom but may be able to help in sharing my learnings gained along the way.
W/r to the credo “buy what you need when you need it” - I think that’s good advice with some caveats. First, if you are on your own with nobody right there with you, then I think some form of signal generator in known working order is essential. If you don’t know what clean, near-perfect signals X, Y, and Z look like on your instrument (scope, DMM, etc.) - then how will you recognize them as you probe in-circuit? The absolute best part of “buy what you need” is that you’ll then learn how to use it much more effectively and retain that knowledge.
Second, used eBay equipment can be an awesome benefit to ramping up quickly - but there are real caveats. Buying a quality analog scope off of eBay can be a huge boon - you can learn a ton from these. However, scopes aren’t precision instruments in a metrology sense. If you buy a nice semi-vintage frequency counter to use with your semi-vintage oscillator (that’s probably making beautiful sine waves at some frequency and phase), which one is right? It’s no surprise that in the background on EEVblog, The Signal Path, Mr. Carlson’s Lab, etc. are lots and lots of gear to compare the “instrument of the day” with. I am absolutely not saying that refurbished/used/vintage kit isn’t a good option - just think carefully of what “known good” looks like on your bench.
Third, treasure the debugging moments. Just today I was picking back up a radio kit that I’d started with a week ago. The very first diagnostic test failed right after I’d finished the first pass of assembly. I checked my solder joints, I replaced (brand new) caps, etc. Okay, back to square one. I extracted the circuit corresponding to the initially assembled portion and built it on a breadboard. I then compared it against the one IC’s data sheet. Those seemed mostly fine and adding the suggested decoupling cap did nothing to help. I then determined that there should be a lot of “hum” on the speaker but that there shouldn’t be as much current sunk from the supply as I was seeing on the PCB. That then focused my diagnostics on the PCB and, sure enough, the headphone jack (a supplied part I had torqued too far) was shorting the audio input to ground. Slow down - think things through - experiment don’t flail - and you’ll learn.
Finally - I saved myself a few dollars building a power supply kit. I learned something about assembly, layout, etc. that’s helped me lay out the one PCB I’ve had made. However, in hindsight just working with soldering practice kits (0603 and up) would have been better and getting a good deal on a basic switching bench supply was easy.
Enjoy!
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