Working on my pong project, many times late at night, i tried many circuits before the "forehead slap" simplicity of 74xx logic

anyway working on the paddle interfaces out of mind schematics i sometimes did stuff that i darn well knew was in violation of electronic laws

blunder #1

first attempt at the paddle interface was quite complex, the first stage involved a transistor latch, which i was using as a bit of memory, i disregarded the current potential of the thing and got a diode quite nasty hot, result = 3 melted spots on my breadboard, and a "branding" of a diode on my left index finger, still, nearly 3 weeks later

blunder #2 was basically the same cpet with a transistor, i grabbed a pnp, stuck it in a place that really should have been npn and now i have a branding of a transistor on my other index finger

i told my wife, if i kept that up i could just wiggle my fingers and check my email

Doh!
I have done things very similar to that as well - my favorite hack is using 7805's to get a quick (and extremelly temporary!) 5V, 1A supply from 12V. As you know, P=IV so 1Amp*(12-5) equals a very hot device
So long as you dont wobble the board you can have the 7805 sat on the board in molten solder (melted under its own heat) at full load - I touched one once and had the same branding affect as you had with the diode!

You live and learn, and forget, then learn again

S.

I've done this with 555 timers before. Apparently, there is a minimum voltage and maximum voltage at which a 555 will oscillate, and going over the maximum voltage does NOT equal a higher oscillation rate. What it equals is a hot 555 chip.