Monday, April 1, 2013

'Magic Smoke' Resistors available off-the-shelf

Anyone that has been around electronic devices for any length of time know that when the devices fail, they tend to go up in smoke, leading to the idea that electronic parts are run by Magic Smoke. Alas our sterilized, sanitized, paranoid society is taking the *fun* out of such things as hands on learning.

While places like Analog Devices' Engineering University are great for learning theory and hands on labs with their hardware, sometimes it is far more educational, and down right *fun*, to learn why things went wrong. Only experience is going to teach one, the important debugging skill, of the differences in smells between burning resistors, burning capacitors, and burning circuit board material. Also teaches the importance of wearing protective eyewear (never know when a backwards part might try to impale itself into the ceiling or ones face if it is closer), and having a electrical rated fire extinguisher next to the workbench.

What brings us to Magic Smoke, is that Vishay has upgraded their old line of Electro-Pyrotechnic Initiator Chip Resistor (EPIC) (and Design Guide and App Notes) to the new Massive Electro-Pyrotechnic Initiator Chip Resistor (MEPIC).
MEPIC resistors, also known as bridge resistors, are resistive elements that convert electrical energy into heat energy in a precise electro-thermal profile for the purpose of initiating a series of pyrotechnic events in a controlled energetic reaction. [They go *BOOM* on command, which is different than Rapid Spontanious Self-Disassembly.]
The new Vishay Sfernice resistor is optimized for electronic igniter applications in automotive safety systems for the deployment of airbags and other safety devices; digital blasting in mining applications; and in fireworks applications for better synchronization of fireworks, music, and special effects.
With firing energy down to 1.5 mJ and a typical ohmic range of 2 Ohms (+/- 10 %), the device provides designers with very predictable, reproducible, and reliable behavior.
Offered in the standard 0805 case size for the wraparound and flip chip versions, with other sizes available upon request, the resistor features easy set-up of firing levels, and is compatible with various pyrotechnic compositions.
Offering ESD withstanding to 25 kV without extra protection, the MEPIC resistor's performance meets no fire/all fire conditions and the requirements of USCAR, AKLV16, and major car manufacturer standards. The device is RoHS-compliant and conforms to Vishay "Green" standards. [Is it not great that Fuzes are 'Green'?]
Almost lost in the mists of time is that in the past manufactures made military specific parts, before someone thought that Commercial Off The Shelf technology (COTS) was a good idea (it wasn't). National Semiconductor's, now part of TI, Application Note #761:Electronic Fuzing covers the basic terminology of Fuzing:
Fuzing mechanisms are devices used to "safe", "arm" and detonate explosive military munitions (such as missiles, mines, demolition charges, explosive shells ranging in size from 20 mm to 16 inches, unguided bombs and various submunitions). Early electronic fuzes developed for 5-inch naval air defense...
Sadly even tho I'm it good standing with my Vishay Rep. Firm, samples of (M)EPIC parts are restricted to people that can show good cause for getting them, so Homeland Security can relax. To bad, think of the fun the people at Hack A Day or Make Magazine could have with some well as those great educational experiences that are being lost...