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Manfred2
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Join Date: Oct 2010
Posts: 76

Tesla Coil Primary Resonance

06/03/2025 8:17 AM

Hi All,

I am trying to find the primary coil resonance on my Tesla Coil. I have done the secondary without any issue, however, when I try to measure the primary I get a dip on the oscilloscope instead of a peak and I don't know why. Can anybody help with this please?
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Haymaker
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Join Date: Feb 2020
Posts: 482
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#1

Re: Tesla Coil Primary Resonance

06/03/2025 11:55 AM

Tesla used sparks to drive his primary. A flux of intermittent frequencies. A flux of duty cycles.

One might look at the resonance of the whole circuit instead. They have these wonderful little VNA instruments now for under 100 bucks. When I was young we couldn’t afford such things…...10,000 bucks.

The Vector Network Analyzers can show all the resonant points and areas. All the impedance thru-out a large frequency range. And singular components too, the resonant steps of capacitors and coils…. and transformers.

Ebay or Amazon. Add a VNA and a function generator to your equipment list. Both under 100 bucks.

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dkwarner
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Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
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#2

Re: Tesla Coil Primary Resonance

06/04/2025 12:47 PM

Depending on where you have the scope connected, it may well be that energy is more efficiently transferred from the primary to the secondary at resonance, so the current in the primary drops.

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Manfred2
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Join Date: Oct 2010
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#3
In reply to #2

Re: Tesla Coil Primary Resonance

06/04/2025 2:58 PM

The secondary is not in place. There is only the primary coil and capacitor.
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dkwarner
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Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
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#4
In reply to #3

Re: Tesla Coil Primary Resonance

06/04/2025 7:19 PM

Then it may be a matter of series versus parallel resonance:

https://www.tutorialspoint.com/difference-between-series-resonance-and-parallel-resonance

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Deefburger
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Join Date: Mar 2011
Location: Sebastopol, California
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#5
In reply to #3

Re: Tesla Coil Primary Resonance

06/05/2025 11:19 PM

Then you are missing the load the secondary supplies to the circuit and are looking only at the primary coil unloaded?

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Manfred2
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Join Date: Oct 2010
Posts: 76
#7
In reply to #5

Re: Tesla Coil Primary Resonance

06/06/2025 11:44 AM

That is what I want.
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Rixter
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#6

Re: Tesla Coil Primary Resonance

06/06/2025 8:13 AM

A capacitor in parallel with an inductor has a high impedance resonance. A capacitor in series with an inductor has a low impedance resonance. Without having access to your circuitry, I'm guessing you have the latter (series circuit).
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Manfred2
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Join Date: Oct 2010
Posts: 76
#8
In reply to #6

Re: Tesla Coil Primary Resonance

06/06/2025 11:45 AM

I need to double check as that may be the reason. Thanks!
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