Digital dice roller

There are a few smells that are instantly recognisable. Nobody can mistake the smell of burnt toast. Hair on fire has a unique smell you can’t mistake for anything else. That hot asbestos-y smell as the clutch of your car gives out, or that acrid stench of burning rubber are other examples (laser-cut lasagne absolutely stinks like nothing else, but I’m not sure there are many people who could testify to that one).

Another instantly recognisable smell is one of burning electronics. At first, it just smells “warm”. It’s hard to describe. But it’s a smell that says “something (that isn’t toast or hair or rubber) is getting *very* hot”.

And then, inevitably, the electronic component gives up and lets all smoke out. (you know that’s how electronics work, right? Magic smoke).

It all started when when my latest order from Amazon arrived – replacement OLED/LCD screens to replace the ones that have driven me crazy over two days, by remaining resolutely hidden (despite my turning the workshop upsidedown – twice – trying to find them).

I’d already built the circuit, tested the code, made the circuit boards (the ones I ordered from China *still* haven’t turned up yet) and built a working prototype; https://www.beastsofwar.com/project-entry/1634402/ – it was just a matter of repeating a known, working sequence.

But as soon as I completed my second circuit and hooked up a battery, nothing happened – the screen didn’t light up. There was no evidence of anything actually working. I left it connected while I looked at my circuit on screen….

…. and that familiar smell of “getting hot” wafted across my desk. Sadly I was too slow disconnecting the battery – the fizz-pop as the magic smoke was released was as disheartening as it was inevitable.

This is the OLED  I used for my (working) prototype:

And eventually I got the new screen working. But there was one major difference…

If you look really, really closely at the labelling of the pins you might spot that the power and ground pins have been swapped around! Which means using my original design, somewhere in the circuit, I was creating a “dead short” to ground. And that made things go fzzzt pop!

Fixing it was easy enough. But it also means I’ve had to create a second design of the PCB for these OLEDs.

All of which means, it’s time to crack out the ferric chloride again.

And that’s another of those unmistakable smells – overriding the thermostat on your tank heater to heat the ferric chloride, then forgetting about it and going for a brew in the garden for half an hour… don’t ever do that! (again).