I have a very simple circuit and want to see the current in the inductor. But I do not know why switch is behaving like that...enter image description here

Actually, I supposed to get KA range current. but it gives me very small values.enter image description here

Following I added the same circuit with 5s delay for clafication. enter image description here

  • \$\begingroup\$ Did you graph what your V2 pulse voltage looks like? I'm suspicious of the values you use to define the pulse. It appears that you have specified the rise and fall times to be 0 and I don't think you will really get that from the simulation. \$\endgroup\$ – Elliot Alderson Feb 22 '19 at 20:33
  • \$\begingroup\$ I believe it's your switch not switching fully....lower Vt or raise the V2 pulse level a fraction and it'll work. \$\endgroup\$ – Phil G Feb 22 '19 at 20:58

There are several issues:

  • You have no ground on the controlling side of the switch. I'm surprised the simulation starts.
  • You are using a threshold voltage of 1v for the switch, but a driving voltage of 1V amplitude. Even if you have negative hysteresis (bravo!), the switch will not conduct the way you need.
  • You are using zero rise/fall times, which does not mean instant times, that would be a physical impossibility. When they're zero, LTspice uses 10% of Ton for them.

Also, a minor warning: the default inductance, unless it has a coupling associated, has a series resistance of 1mOhm, which may, or may not be wanted. That's up to you to know.

Here's a reworked version of your circuit, I made several assumptions as I have no idea what is your purpose:



Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.