75 years ago, wartime shortages meant that meters were not readily available. The November 1943 issue of Popular Mechanics offers this tip for checking whether high voltage is present. A small capacitor (.25 to 2 uF, 400 volt) has spaghetti tubing placed over the leads, which are connected where the high voltage is being tested for. The capacitor is then removed and the ends shorted. A spark indicates the presence of high voltage.