21. Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of megahertz. 22. So the first generation watches had low frequencies of a few kilohertz , limiting their accuracy. 23. When touched horizontally against the center of a tooth it vibrates at 5 kilohertz for one second. 24. He discovered that the squirrels were making very short screeches at a frequency of about 50 kilohertz . 25. Poulsen's arc could generate frequencies of up to 200 kilohertz and was patented in 1903. 26. An external or secondary circuit drives the switching, typically at tens of kilohertz up to several megahertz. 27. The Armstrong method begins by generating a carrier signal at a very low frequency, say 500 kilohertz . 28. In 1971 the clockspeed of Intel's original microprocessor, the 4004, was a feeble 100 kilohertz . 29. They can hear a frequency of up to 91 kHz ( kilohertz ) and send sounds of 70 kHz. 30. Most FSM's can be driven to several wavelengths of tilt, and at frequencies exceeding one kilohertz .
