Show tube insurance that Is worth remembering probably pinny ninny tubes ire gru burned out every year by connecting a high voltage H B battery across their filament terminals there are many ways to prevent present such an from happ happening ning and one of me lie easiest edlest Is to connect co a high resistance e in the negative Degi ithe ic iund ad to the 1 it I battery an ordin 1 ry 10 watt electric light bulb I 1 Is one high resistance which rony may be used for this purpose if ole use of the lamp calls caused a howling noise to be heard shunt it with a I 1 alfil condenser ae 4 |