Circuit for eliminating parasitic capacitance of coil

[ZOUjiarui]

I saw such a circuit, and I suspect that it would eliminate the parasitic capacitance of the coil.
It consists of four resistors and is connected in series inside the coil
The circuit is two resistors in parallel and two resistors in series.

[ZOUjiarui]

Resistors in series and in parallel are connected in parallel to form a circuit

[gurdal]

İmage ???

[ZOUjiarui]

It's like this.

[ZOUjiarui]

[Jeg]

ZOU is right. The total reistances network form a specific resistance value which can replace all of them.

[Carl-NC]

How does a resistor in the coil eliminate capacitance?

[bbsailor]

I saw such a circuit, and I suspect that it would eliminate the parasitic capacitance of the coil.
It consists of four resistors and is connected in series inside the coil
The circuit is two resistors in parallel and two resistors in series.

Parasitic capacitance from all sources including coil turn distance apart, insulation thickness, dielectric constant of insulation, MOSFET capacitance and coax capacitance all affect the coil resonance frequency by lowering it. If your goal is to make a faster coil, then trying to minimize the capacitance that the coil sees is a good objective. Since the coax has a fixed capacitance based on the physical shape and diameter of the coax, then being creative and putting the minimal active and passive components at the end of the metal detector aluminum arm shaft would eliminate most coax capacitance. Then finding a MOSFET coil driver with low COSS would help keep the coil resonance higher.

The goal is to reduce the capacitance energy storage that the discharge pulse sees so it can turn off with less oscillations and require a higher value of damping resistor so the RX cycle can turn on faster and then pick up smaller targets easier.

These are just some of my thoughts to get the creative minds of geotech1 forum members moving in a new direction.

Joseph J. Rogowski

[GeoMax]

From my point of view has the resistor network the purpose to adjust the coil individual to the correct damping resistor value only. Nothing more nothing less. The use of several resistors in series and parallel is because of the limited dielectrically strength of the used resistors.