# I have a problem with using a voltage controlled switch in Pspice

When using the voltage controlled switch in Pspice, the current flowing on the other side of the switch is equal to the current flowing through the voltage source controlling the switch.

Why is it so?

I want to see the current source value on the other side.

## 1 Answer

I suppose the current you're referring to is the 2.000 A going into the bottom pin of the switch (right side) and the -2.000 A going out of the upper pin. If so, that makes perfect sense since you are measuring the curent into the pin, and the current going out of the pin. So for the first case you are looking along the direction of the current, as it goes away from you but in the same direction, and in another you see the current coming towards you, hence the negative sign.

If you expect to see zero current when the switch went off, you won't see it, since you are using a current source, which is meant to deliver the current no matter what. So whether the switch is on, or off, the same current will flow, but the voltage readings will be different, depending on the values of Ron and Roff.

Also, don't forget that, in SPICE, two pin elements have a convention for the reading of the flow of the current: it goes into pin 1, and goes out through pin 2. This is valid for all R, L, C, D, sources, etc.

Ignore my comment (deleted). The connections are fine, but the readings are strange, indeed. The input of the switch is voltage mode (i.e. there is no current consumption), so not only R2 is useless, but the current should be zero (or numeric residuals, like 6.006 nA = 6.006e-9). I don't know why it shows 35 A. It shouldn't show anything, you shouldn't even be able to measure the current through the pins, they're mostly there to complete the package, to give a handle for taking a voltage from somewhere.