Perhaps a different kind of dumb mistake than the ones we were talking about a while ago, but also related to the recent discussion of over-voltage and reverse-voltage protection: My two-year-old daughter likes to play in my office. I give her a breadboard and wires and some old chips, and we plug them in at random and move them around. See e.g. . Occasionally we wire up a LED, resistor, and switch to a 2xAA battery pack. The point is to make her feel comfortable in that environment, and she is. Often she goes through my shelves and demands to know what every part and tool is. "I want... something... NEW," she says, staring up at the parts drawers. Pointing: "That drawer." My plan is that eventually she will start building increasingly complex projects on her own without really noticing it, and then she will become a geek and have good job prospects but no social life, so that she will be emotionally dependent on me and I will be able to control her. Or perhaps there could even be a positive outcome; who really knows. I digress. Today I was talking on the phone and not paying close enough attention. I did notice when she had a screwdriver and was finding screws to push it onto - she was perilously close to some live AC outlets, so I put a stop to that and reminded her not to get near them because they're very, very hot. So I wasn't totally ignoring her. And when she looked at the voltage switch on my small variable-output switching power supply and decided to move it, I was watching - but not fast enough to catch her before she moved it from 3V to 12V. That power supply was running a breadboard containing an XBee radio module, which has a max Vcc of 3.4 V. I immediately grabbed the supply and shut it off. Gently told her that I thought she had broken it (because I think she should know that sort of thing), but that it wasn't her fault, but that she shouldn't move switches without asking. And vowed silently to turn ALL accessible AC outlets OFF when she's playing, because there are far worse possibilities than burned out chips. Went and checked later: Yes, the XBee was done. When I plugged it into a different carrier board, I could smell the remnants of its magic smoke and feel it getting way too warm. Pulled it out fast and wrote a eulogy on it with marker ("TOAST"). A $36 lesson. On the plus side, the PIC (688) was unscathed - popped in another XBee and the gadget worked fine. Good old sturdy PICs! By comparison, this is the third piece of my 7-piece MaxStream dev kit to die, and the first with an observed cause; both an XBee and the USB carrier board just seemed to become bored with life at different points. So it goes. -- Timothy J. Weber http://timothyweber.org -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist