12V car cig lighter adapters - safe?

I actually did that many years ago.

Why?

Because that was the rules of the challenge. As I said, it was an exercise in design.

FFS...

I used to work on them many years ago. They were widely used on videogame boards to prevent piracy along with scrubbing IC numbers off. Made faultfinding a real bitch.

Lobster used his keyboard to write :

I use several of them and the only protection I have seen has been a fuse in the plug to limit the current.

The gadget should be built such that it has all the protection from surges built in to it.

Only if the cheapo item is very badly built. I have paid £1 each for them and they have proven to be well built. I have paid £5 each and they have been rubbish.

Tested, not really. Inspected, probably. Does it look solidly built, does the plugs make good contact and say in?

A shame they standardised on the reuse of a socket intended for light a ciggy, instead of something more appropriate.

Plenty have a power supply built into the plug. Things like Tom Toms for example.

How about describing, in order of effectiveness, the steps you would take to mitigate simultaneous switching noise.

Or how about describing metastability in a flip flop what you would do about it, and why.

MBQ

I once used a 10pF disc to ground, why? Although TBH that was more of an edge overlap instability and the cap slowed the signal rise times enough to not cause the problem.

Duh. I'd wear sandals instead.