What Part of ______________________ Don't You Understand ? - One for mapj1 ?

These are both horrible designs. Mikes depends on the transistors being mismatched to do anything, and if the power supply is raised slowly enough would still do nothing. Probably it would work 90% of the time and do something! The first is very odd, in that VR2 is not required and does nothing useful, and this circuit was probably thought up by a 1st year undergraduate. Good for MUGS I suppose and might cause a little discussion over coffee, which might be the idea. Consider the temperature stability of a regulator against a voltage reference, .some are good, some are not! The hysterysis of the comparator circuit would probably stop most of the relay chattering I suppose.

These are both horrible designs. Mikes depends on the transistors being mismatched to do anything, and if the power supply is raised slowly enough would still do nothing. Probably it would work 90% of the time and do something! The first is very odd, in that VR2 is not required and does nothing useful, and this circuit was probably thought up by a 1st year undergraduate. Good for MUGS I suppose and might cause a little discussion over coffee, which might be the idea. Consider the temperature stability of a regulator against a voltage reference, .some are good, some are not! The hysterysis of the comparator circuit would probably stop most of the relay chattering I suppose.