A litany of dumbassery

What, and ruin the surprise?


so I bought the Plum Audio version of ornament and crime module well when I was assembling it I chipped the oled screen on the mounting screw heads . apparently they don’t like that and do not work with even the tinniest chip in them .
they were nice enough to replace it for me for shipping .
all good now and have moved on to the build progress thread .


One shall not plug 220V in the secondary circuit of a 220-12V transformer.
Not a good idea. Like at all. Magic smoke coming from a cable is not that magic…
(The thin cable turned into a fuse, and may have save more than a small transformer…)

At least, I learned my lesson and made a circuit breaker protected plug to test further projects…


Sam was kind enough to give me a 3 x splashback when I went to the museum a few months ago. Finally built it and after correcting a few minor issues it still wasn’t working. I did some very diligent error checking to figure out -12V wasn’t getting to the opAmp.

Regret to inform I am Idiot and apparently mangled the new power cable on my test rig and, ironically, didn’t test it


Build the cable tester, it’s worth it’s weight in fiberglass…

1 Like

As said by others, a cable tester is a nice tool. Have a look at the one I’m using whenever I make a new cable:


That’s really neat . I usually just stick an unused socket onto the plug and use a multimeter on the pins. I don’t know why I didn’t test this one !

1 Like

Ugh I sent all day working up panels out of scrap plastic but when I started making hokes for components they shattered. The plastic is far too britle. If I wasn’t off my head with covid I’d be furious.

1 Like

Masking tape and taking it slow are your friends.


what christian said, plus making pilot holes.


Stupid layout mistake, but easy to fix with some tape :wink:


Could always bend the support in a bit? Saves it incase the tape wears through =D


Overlapping courtyards? DRC should catch that. Or… does it?

Oooh. No, it doesn’t, because each has only a front courtyard, and when one is on one side and one is on the other, they don’t overlap!


Yes, and I also sometimes ignore overlapping courtyards because there is so little space on the PCB :wink: bad practice, I know, but sometimes it can save me a bit of a headache :see_no_evil:


Nah, it’s not bad practice. It’s good practice to check and to decide whether it’s a real problem or not. Sometimes the courtyards are just bigger than they need to be.

And sometimes not but there’s a workaround.


thats one of the new modules that you are still " working around " ? .

That’s the Barton full wave rectifier.


I sometimes ask myself, “Why do I bother with polarity reversal diodes? I use box headers. I check my cables. What could go wrong?”

Today I made a little modified bus board for my workbench. I tested it, looked good; the LEDs on it lit up as they should.

Tonight three VCOs were saved from oblivion by their polarity reversal diodes…

“How could the bus board be wrong? The LEDs wouldn’t light up if it were wrong! … Unless the LEDs were backwards too…”


one of the few things i do religiously is to check any power stuff I build with the meter. but thats probly cos half the time they don’t work :wink:


When creating noyce PCBs, after reading messages for shorts and so, be reminded to check what you write on the PCB (like resistor values). Your future you is dumb and will follow exactly what’s written.

Inverting resistors caused:

  • a Schmitt trigger not to work (and the VCO not to oscillate)
  • a sine shaper not to shape (and the VCO not to produce a sine)

I guess I am lucky, I got no magic smoke so far.