Effects of Adding a Rheostat to a Violet Ray Machine — Frequency vs. Resistance
Are any of you folks out there familiar with the Tesla Coil Violet Ray Machines? The typical power supply for these old machines, some dating back to the very early 1900's, consisted of a magnet coil, an interrupter (or rheotome) and a capacitor. The input voltage and the power of the device was mainly determined by the thickness of wire and the number of turns on the magnet coil and could range from a few DC volts all the way to 220VAC. The machines ran effectively on both DC and AC. The power supply fed between 1000V and 2000V to the primary winding of a very small Tesla coil. On average these high frequency discharge coils were on average 4 to 5 inches long and 1 to 1.25 inches in diameter. This would include both the primary and secondary windings. Most American violet ray machines had just one way to adjust the power output and that was through an adjustment knob that altered the pressure exerted on the interrupter contact spring. The other and less frequent way to modulate the power output, is through the use of a rheostat. Rheostats were frequently found on European violet ray machines either by themselves or sometimes in conjunction with an interrupter control.
There are two ways to add a rheostat into a violet ray machine circuit to alter it's high frequency output. 1st one can simply use it to short out the primary winding of the high frequency coil. The 2nd way is by installing it series between the power supply and the primary winding of the high frequency coil. Rheostats implemented in violet ray machines usually used pretty thin wire, perhaps 24 or 26 gage magnet wire and had between 80 and 150 windings.
For any engineer reading this that is still with me, please tell me if my logic is correct.
My hypothesis is that when a wirewound rheostat is hooked up in series between the power supply and the primary winding of the high frequency coil, it will effect both the power and the frequency of the current going to the primary winding of the high frequency coil, as it is working both as a variable inductor and a variable resister. Is this Correct?
In the second scenario, with the rheostat installed to short out the primary winding of the high frequency coil, it is my hypothesis that the rheostat will not in any way alter the frequency of the current flowing to the high frequency coil and only behave as a variable resister. In other words, used in this configuration, the induction caused by current flowing through winding of the rheostat will not effect the frequency of the current flowing to the high frequency coil. Is this Correct? Or is the frequency of the current flowing to the primary winding of the high frequency coil still being altered?
Can anyone help me understand these concepts more fully?
Thank You Kindly,
Steffan Heydon
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