Potentiometers not working?

[PaddyCymru]

Do potentiometers work??  See attached (running) screenshot.  Simple voltage divider - (12V DC supply) - varying pot with Multisim 2001 simulator running or not running has no effect; volt drops across both nominal 1k resistor/pot remains 6V each regardless of pot setting.

Am I missing something??

Also, I have trouble getting SCRs to work with phase-shift control - this is what prompted playing with pots.

Paddy

[lacy]

You need to connect the wiper of the pot back to either the junction of the two resistors or to ground. As you have it now the circuit is seeing the full 1K resistance across the outer legs of the pot. This situation also occurs in a real circuit. 

As far as SCR's go, I would have to examine your circuit in order to determine what may be occurring there. I seem to recall that they do have problems in AC applications but I may be confusing these with the Triacs that I know don't work in AC Apps.

[PaddyCymru]

I can't believe it!  I treated the pot as a generic variable resistor with no thought to the wiper terminal.  I'm embarrassed!!!!

As for the SCRs - I'll play again with a (hah!) working pot.

Thanks Lacy

Paddy

[kittmaster]

it happens to the best of us.....sillyness happens.....;)