#### Paul Colby

Gold Member

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Hi,

I have an air wound 0.736 mH coil in series with a 3.5pF capacitor being driven with a function generator. Ideally the series resonant frequency should be around 3.13 MHz. The internal impedance of the function generator is 50 ohms or so. At resonance the voltage across the cap should be

where R is 50 ohm plus whatever additional resistive losses creep in and ##V_o## is the voltage across the L C pair.

I would like to maximize ##V_c## and monitor it's value at the same time. The problem is the capacitance of the scope probe or coax swamp out the 3.3pF. Even with this problem the ##V_c## is at 500V at 10V applied and I would like more[1]. My question is what approach would one suggest to monitor the voltage while operating at peak voltage without adding undue additional capacitance. The exact resonant frequency isn't that much of a concern.

[1] above a MHz this isn't a shock hazard and getting close to a burn hazard isn't feasible or desired. With my divide by 10 scope probe I get ##V_c/V_o = 54## at 1MHz.

I have an air wound 0.736 mH coil in series with a 3.5pF capacitor being driven with a function generator. Ideally the series resonant frequency should be around 3.13 MHz. The internal impedance of the function generator is 50 ohms or so. At resonance the voltage across the cap should be

##V_c = \frac{1}{R}\sqrt{\frac{L}{C}}V_o##

where R is 50 ohm plus whatever additional resistive losses creep in and ##V_o## is the voltage across the L C pair.

I would like to maximize ##V_c## and monitor it's value at the same time. The problem is the capacitance of the scope probe or coax swamp out the 3.3pF. Even with this problem the ##V_c## is at 500V at 10V applied and I would like more[1]. My question is what approach would one suggest to monitor the voltage while operating at peak voltage without adding undue additional capacitance. The exact resonant frequency isn't that much of a concern.

[1] above a MHz this isn't a shock hazard and getting close to a burn hazard isn't feasible or desired. With my divide by 10 scope probe I get ##V_c/V_o = 54## at 1MHz.

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