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Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Make a 1:100 transformer with a ferrite toroid, the one turn is connected to the Tesla coil secondary base wire. The other side is RF grounded. Then, one side of the secondary goes to common ground, and the other end goes to the antenna cap via a 1kohm resistor. You may want to add a resistor of maybe 10 ohms in parallel with the CT's secondary if the voltage rises too high.
Also, you have to ensure the phasing is right. If the coil does not run, reverse the secondary.
Registered Member #618
Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628
Just for clarification Arcstarter is correct but the wording may get you confused, by "Then, one side of the secondary goes to common ground, and the other end goes to the antenna cap via a 1kohm resistor." He's refering to the CT's secondary it is obvious but may confuse somebody. Also you may have been able to find the answer to your question if you did a search of the forums.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Ken M. wrote ...
Just for clarification Arcstarter is correct but the wording may get you confused, by "Then, one side of the secondary goes to common ground, and the other end goes to the antenna cap via a 1kohm resistor." He's refering to the CT's secondary it is obvious but may confuse somebody. Also you may have been able to find the answer to your question if you did a search of the forums.
Give a man a fish and he will eat for a day. Teach him how to fish, and he will eat forever.
Registered Member #2161
Joined: Fri Jun 05 2009, 03:36PM
Location:
Posts: 247
Arcstarter wrote ...
Ken M. wrote ...
Just for clarification Arcstarter is correct but the wording may get you confused, by "Then, one side of the secondary goes to common ground, and the other end goes to the antenna cap via a 1kohm resistor." He's refering to the CT's secondary it is obvious but may confuse somebody. Also you may have been able to find the answer to your question if you did a search of the forums.
Give a man a fish and he will eat for a day. Teach him how to fish, and he will eat forever.
Or perhaps in the capitalist society of today:
Let the man starve, if you teach him to fish he will cut into your supply and profits.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
What is the purpose of the 1k (or 10k) resistor in series with the CT output? If its a current transformer, it should transform current and any additional resistor in series just adds unwanted voltage drop but doesnt change the current, right?
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Dr. Kilovolt wrote ...
What is the purpose of the 1k (or 10k) resistor in series with the CT output? If its a current transformer, it should transform current and any additional resistor in series just adds unwanted voltage drop but doesnt change the current, right?
It is current limiting. If you use a shunt/burden/whatever resistor to drop the voltage enough, it will not be such a problem. As long as the diodes are not clamping too much. I once actually blew a 1kohm limiting resistor open. Not to mention, with no burden, i have gotten CT's running CW pretty warm. Uncomfortably so, in fact.
As long as the phase is still correct, current and voltage do not need to be worried about so much. As long as it has enough to bring the 74hc14 gate input high, about 2.5 volts minimum, and low enough current flowing through the diodes so that they do not asplode, it is fine.
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