Another thought by the uninformed

[RayNM]

Was wondering about something. If you connect another fet across the coil and fire it when you assume the coil is saturated and and just as the pulse fet turns off, then shut off the second fet say 5 usecs later, will this decrease the turn off time. It seems to me that in doing this the short created by the second fet will increase the magnetic pulse and give you a better received signal from the target. Or am I all wrong on both counts. I have not tried this yet don't know if it is possible to do. Sometimes my mind wanders and wonders. If this is a totally bogus Idea just let it go by the wayside.
RayNM

 

[Eric Foster]

Hi Ray,

The second Fet will look like a short across the coil for the 5uS you have it turned on. Assuming the Fet is 0.5 ohms, and the coil resistance is 1 ohm, with an inductance of 300uH, then you have a coil turn off time constant of 200uS. However, if your second Fet opens at 5uS, then you will be 5uS down your 200uS coil decay TC. All you have really done is extended your TX pulse by 5uS and switched off at a slightly lower amplitude. No advantage I am afraid.

Eric.

 

[RayNM]

Thanks Eric It was just a thought and after you explained it it makes sense. Should have tried it myself before posting.
Ray

 

[Eric Foster]

Hi Ray,

No problem. I often have ideas that seem quite innovative, when just thinking about them. When I try them out, it is a different story.

Always happy to help those that have just boarded the PI boat.

Eric.