#43 absolute current ?

[Samir Sabri]

I need to have a switch controlled by current, but I need to treat the current value as absolute value, so that wither its positive or negative, I can use the same model settings for the switch.

is there any possible way to achieve this?

[Samir Sabri]

the source for this question is based on a discussion here: https://electronics.stackexchange.com/questions/450938/recommendation-for-simple-relay-model

[Holger Vogt]

Use two switches in parallel, one opened with positive, one with negative current.

Or use a B source with an expression containing the current and a ternary function a?b:c to check if the current is positive or negative.

[Samir Sabri]

Can you please give simple example of both approaches? I am just very new
to Ngspice and I've just discovered B

On Wed, Aug 7, 2019, 12:27 AM Holger Vogt h_vogt@users.sourceforge.net
wrote:

Use two switches in parallel, one opened with positive, one with negative
current.

Or use a B source with an expression containing the current and a ternary
function a?b:c to check if the current is positive or negative.

---

• [support-requests:#43]
  https://sourceforge.net/p/ngspice/support-requests/43/ absolute current ?*

Status: open
Group: v1.0 (example)
Created: Tue Aug 06, 2019 05:42 PM UTC by Samir Sabri
Last Updated: Tue Aug 06, 2019 05:55 PM UTC
Owner: nobody

I need to have a switch controlled by current, but I need to treat the
current value as absolute value, so that wither its positive or negative, I
can use the same model settings for the switch.

is there any possible way to achieve this?

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[Samir Sabri]

Can you please check this: https://electronics.stackexchange.com/questions/453551/current-controlled-switch-with-negative-current

[marcel hendrix]

On 2019-08-19 06:34, Samir Sabri wrote:

[..]

I need to have a switch controlled by current, but I need to treat the
current value as absolute value, so that wither its positive or
negative, I can use the same model settings for the switch.

is there any possible way to achieve this?

Instead of driving the switch directly from a network current,
add a B-source to control it indirectly. The B-source equation
allows one to apply an arbitrary expression to the node voltages
and branch currents that are to set the switch state. Adding the
B-source allow to use either a current or voltage controlled
switch.

-marcel