Using CMOS circuits and operational amplifiers of the time, this circuit was found in the September 1977 issue of Radio Electronics magazine. The circuit is powered by a 15 V power source.
Carbon microphones are no longer used in most projects. However, finding one in the scrap metal, it...
This circuit produces a strong tone of audio or ultrasound, depending on the values of components C1 and...
This alarm from an old 1978 publication uses PNP transistors and driver and output transformers that are...