ABSTRACT
Vacuum tubes were the forerunners of semiconductor devices such as diodes and transistors. The semiconductor alternatives have many advantages over their vacuum tube fore-bears – size, robustness, reliability, power consumption, and linearity of operation come to mind. When using tubes it is quite important to observe the correct supply voltage levels for heater connections. Running the heaters too low is likely to compromise the effective operation of the valves, although is generally not a major problem. Standard tube circuits are a vast and complex subject area. High voltages are involved, often in excess of the mains voltage powering the amp.
