Detailed information is given for the construction of relatively simple, efficient pulse equipment. The repetition rate of the pulse generator varies between once in 10 sec and 25 000 times a sec with a pulse duration from to 100 msec. Pulses of sinsuoidal oscillations may be generated in the frequency range from 50 cps to 100 Mc. The circuits are free from ringing at frequencies below 5 Mc. The power output for pulses of less than 2‐msec duration is between 50 to 250 w at frequencies below 10 Mc. A thyratron stage produces a triggering pulse to activate a monostable multivibrator. The adjustable‐width multivibrator pulse passes through a cathode follower and furnishes the screen voltage for the output tube. If the frequency is below a few Mc, the output tube may be used to gate a sinusoidal voltage supplied by a standard signal generator. But for high power or at high frequencies, the output tube is preferably driven as a gated, self‐excited oscillator.
The receiving amplifier may be connected in parallel with the output of the pulse generator so that the same transducer can be used as both sound projector and microphone. This amplifier limits the large voltage of the driving pulse and is capable of full sensitivity immediately after this pulse has decayed. Some valuable experiences with acoustic transducers are discussed.
