Will it be infallible though? I remember Boris Onishchenko in the 1976 Olympic Modern Pentathlon?
During Onishchenko's bout with their captain, Jim Fox, the British team protested that Onishchenko's weapon had gone off without actually hitting anything.
In electric épée fencing, a touch is registered on the scoring box when the tip of the weapon is depressed with a force of 750 grams, completing a circuit formed by the weapon, body cord, and box. It was found that his épée had been modified to include a switch that allowed him to close this circuit without actually depressing the tip of his weapon. Unlike foil, there are no off-target hits in épée, so Onishchenko could get away with this form of cheating if it appeared to onlookers that he had struck anything at all.
Newspapers decried him as "Disonischenko" and "Boris the Cheat". Onishchenko earned the enmity of other Soviet Olympic team members: for example, USSR volleyball team members threatened to throw him out of the hotel's window if they met him.
I should really purse my lips, but there is a certain caddish swagger in rigging up a switch that let's you score at will that appeals to something disreputable in me. Not knowing what Onishchenko looks or looked like, I can't help but visualise him as Terry-Thomas.