This circuit uses a PLL4046 oscillator to excite a piezoelectric ceramic. The circuit is from an October 1994 Electronics Now magazine.
The transistors of this circuit found in an English 1980s documentation may be the modern BC548...
This circuit was suggested by a Radio Shack publication from the 1980s. The purpose of this...
This circuit was published in a 1977 Radio Shack catalog. The PNP transistor may be BD135 and NPN...