This interesting circuit for SMD assembly appeared in the November 1987 issue of Radio Electronics magazine. The phonons are generated by selected resistors that are fitted to the assembly.
This low noise preamplifier has a gain of 19 dB in the 30 MHz band. The circuit is from the 80s....
Found in American documentation from the 90s, this configuration detects the direction of rotation...
This circuit generates a 5.3 kHz linear ramp with the indicated components. The 7555 is the CMOS...