Automatic delay switch - with visual countdown

N N1 ... N6 = IC3 = 40106 82606 automatic delay switch .. with visual countdown M. A. Prins 5V It is often said that two heads are better than one but this numerical advantage applied to hands could also be a great asset, especially when using probes to test a complex printed circuit board. It is an absolute certainty that the test probe that you have just painstakingly con- nected will flip itself off at the instant that the power is switched on. Further, it is a known fact that it will land with unerring accuracy on the most "sensitive" part of the circuit - and discharge the smoothing capacitor across the input of the circuit! How well we know the problem! The title of this circuit could well have been "Frayed temper adjuster" since it is capable of just that. It allows the use of both hands to position and hold the probes while the power to the circuit is applied automatically, after a short delay. It even tells you (visually) when this is about to happen. An astable multiv...