G. James, G. R. Polgreen and G. W. Warren, the principles are outlined of various kinds of valves for the measurement of alternating voltages (including ‘slide-back’, peak, grid-leak and anode ...

But there is another kind — a very old kind — called a pulsejet ... including a one-way valve design with no moving parts. A pulsejet expels exhaust and intakes air through the same hole ...