Vacuum Tube Preamplifier Analysis and SPICE Simulation

Posted on Feb 6, 2014

The concept of an AC model for the triode is presented and the equivalent circuit technique is described. Theoretical calculations for amplifier gain and frequency response are derived and compared to simulation results in the SPICE3 environment where good agreement is shown. The characteristic properties of AC and DC signals are apparent from fun

Vacuum Tube Preamplifier Analysis and SPICE Simulation
Click here to download the full size of the above Circuit.

damental circuit theory. As an example, a capacitor behaves as a DC block. However, it will pass AC signals in general, but the transfer will be contigent upon signal frequency, type of capacitor, and total capacitance. Here it should be noted that these differences are attributed to the mechanism of current flow in each case. DC signals move charge by conduction. Electrons from one part of the circuit travel continuously to another point due to an electric field that is created by a potential difference, or voltage. Once the capacitor is charged up by the conduction of charge to each plate, the capacitor appears as an open circuit to DC signals. By contrast, AC signals move through capacitors by the mechanism of displacement. Small amounts of charge are moved to and from the plates of the capacitor. They are not conducted through the capacitor. However, this displacement of charge is the means by which AC signals propagate through capacitors. Lastly, it is important to understand that the AC signal is superimposed upon the DC signal and thus the two components obey the mathematical laws of superposition: namely, the AC and DC components can be considered separately and superimposed. However, it should be noted that this is only true to a first order since AC nonlinearities in the tube will give rise to DC components, but this is beyond the scope of this paper. It is equally important to recognize that the two components...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    5 And 12V Ac Powered Switching Supply
    PIC16F688 Based Digital Voltmeter with a PIC mictocontroller
    Logic Probe With Sound
    LED Brake/Rear Light Specifically for motorcycles Circuit diagram
    vackar vfo oscillator
    1kH Synthetic Inductor
    Servo-Checker JR / Futaba
    Help in identifying the schematic symbol
    Body Charge Detector
    Delaying the release of DC relay circuit
    Application of IR2130 three-phase fixed frequency output of the power supply system wiring diagram