The important feature that works in an amplifier is an Air Inlet Port, Air Drive Tube
, Drive piston, Upper Tappet Valve, Pilot Air Tube, Spool Valve, Lower Tappet Valve, and Pilot Vent, Outlet Muffler, Inlet Check Valve and Outlet Check Valve. The amplifying devices currently available are Vacuum Tube (Valve) and Bipolar Junction Transistor (BJT), and Field Effect Transistor (FET). First of all the unit is powered directly from the 120 volt AC line, with no power transformers and the filaments are wired in series with the total adding up to 117 volts i.e. (35 35 35 12).
The positive supply is full-wave rectified using solid-state diodes for better voltage regulation and lower noise. On the other hand, we also have a regulated negative supply of -140 volts, which provides the source for separately adjustable output tube grid bias and by this eliminates the need for a cathode resistor, and its attendant effective supply drop and by suitably changing the power transformer, the circuit can be used with 240 VAC mains.
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