Swamping Resistor ( Just Curious)

[James]

I was curious about the swamping resistor across the search coil. What effect does it have on the over all wave shape of the received target information with respect to the OP Amp input. Any Ideas? Tank you Jim

[Qiaozhi]

I was curious about the swamping resistor across the search coil. What effect does it have on the over all wave shape of the received target information with respect to the OP Amp input. Any Ideas? Tank you Jim

Assuming you mean the "damping" resistor:
The idea of this resistor is to remove (damp) the ringing that occurs when the mosfet is abruptly turned off. The value should be such that it provides a smooth exponential response. With too little damping, ringing (or some overshoot) will be seen. With the correct value, the coil will be critically damped. Too low a value will reduce sensitivity.

[James]

Thank you for your response, Yes the swamping resistor is the damping resistor. Thank you again for your time. Jim

[kt315]

https://www.amazon.com/Inside-Metal-...rhf_ee_p_img_2

ITMD is accumulator of your present and future answers on your Qs. believe me now Jim.