Simulating LM7915 in kicad with ngspice


i am fairly new to kicad and simulating with ngspice but was successful with a few simple circuits. However i haven’t got sucessful results when simulating a simple lm7915 circuit:

I have loaded a spice model from this library:
Specifically i used /Models/uncategorized/Bordodynovs Electronics Lib/sub/regulators.lib

I also did test with various alternate pin configurations, but without getting the right results.

Can anyone point me in the right direction please?

Thanks in advance!

You did not tell us what you have expected and what you got instead.

The 79xx and 78xx series voltage regulators are a class of approx. 1 A output current devices. Vout is to be expected at -15 V at normal operation in your circuit. Your load resistor R1 is 1 Ohm. The resulting current would be -15 A, not possible with a 7915.

Thank you for pointing a newbie in the right direction.

I was expecting -15V of course and the fault was the high load through the resistor. Just as you said. So i got a pretty high voltage drop.
I forgot to put “Meg” behind the 1.

So sorry for the somewhat dumb question.

Anyway is there a way to simulate (and “measure”) the voltage at non connected wires? So that the resistor wouldn’t be necessary in the first place?

A lot of voltage regulators also have a minimum output current. Which means that if your resistor is too high, the output voltage may rise.

When you’re setting up a new simulation, and you’re unsure about a lot of parameters, start by using values that would give the most reliable results. For an 7915 that would be between hundred Ohm and a few kilo Ohm.

That’s a valueable tip. Thank you!