A non-sinusoidal 120 V voltage can be obtained with this circuit found in the December 1992 Radio Electronics magazine. The power is a few watts.
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...