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...using the concept of "equivalent Plate voltage" the fundamental Child-Langmuir 3/2's Law (which was originally for planar DIODES) was empirically extented to include TRIODES by simply 'equating' a "scaled/reduced" combination of control-grid voltage and plate voltage to what its DIODE equivalent voltage would be:
Vp(diode) = (Vg + Vp/mu)
...here, the TRIODEs control grid voltage (Vg) is a negative voltage (called bias voltage) which exactly equals (and therefore cancels) the 'effective' plate voltage (Vp/mu), which is done by 'scaling/reducing' the plate voltage by the tubes Amplification Factor (AF = dVp/dVg)...and AF is abbreciated as "mu" which is the ratio of change in plate voltage (dVp = output) over the change in control-grid (dVg = input). Thus, the C-L equation for TRIODES becomes:
Ip = G*(Vg + Vp/mu)^(3/2)
...with the voltage within the parenthesis (...) being called the "equivalent diode voltage."
...also, notice that G is still Perveance, but now has a slightly lower value due to the presence and location of the added control-grid element (often abbreviated as g1).
Vp(diode) = (Vg + Vp/mu)
...here, the TRIODEs control grid voltage (Vg) is a negative voltage (called bias voltage) which exactly equals (and therefore cancels) the 'effective' plate voltage (Vp/mu), which is done by 'scaling/reducing' the plate voltage by the tubes Amplification Factor (AF = dVp/dVg)...and AF is abbreciated as "mu" which is the ratio of change in plate voltage (dVp = output) over the change in control-grid (dVg = input). Thus, the C-L equation for TRIODES becomes:
Ip = G*(Vg + Vp/mu)^(3/2)
...with the voltage within the parenthesis (...) being called the "equivalent diode voltage."
...also, notice that G is still Perveance, but now has a slightly lower value due to the presence and location of the added control-grid element (often abbreviated as g1).
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