center tapped transformer

[Henry9316]

Hello everyone I hoping to get some help or advice concerning the "TRANSFORMER_CT_RATED" in multisim. I am not able to get the transformer to work properly, even off examples from my textbook. Any circuit I construct in multisim just will not work. Here are some snippets:

The picture after my Multisim simulation is one of the few examples given to me, I also am going off of Malvino's textbook and still cannot get any cicruits to work. Can some one give me some advice on what I am missing and doing wrong with the Center tapped transformers and maybe some material to read over. Thank you

[jrshedden]

Hi,

If you look at the transformer secondary and see red lines like that, it means it's been run outside it's ratings and burned out. Watch the secondary carefully when you click the simulate button. You should see two puffs of smoke. You can see the ratings of the transformer by double clicking it and looking at the value tab.

You're putting in 120 volts to a step up transformer that is going to be 240 volts center tapped across the secondary (factor 2 shown below the transformer). The diodes are only rated to block 50 volts, so they look like shorts and the transformer blows due to over current. You can experiment by putting in more substantial diodes (1n4007 can block 1000 volts).

I recommend you just drop the voltage to 12 volts. Also, I would use the other 4 channel oscilloscope. The Tek looks pretty, but the position controls don't seem to work (for me anyway) and the output doesn't go to the grapher. The unconnected grounds you have on the schematic probaby don't matter. It's a good habit not to leave unconnected parts floating around. All inputs to components should be connected to something appropriate when you get into more complex designs.

Good Luck.

Jim S.

[Henry9316]

Okay thank you very much , Yes I had zoomed in very very closely on the puffs of smoke.. I will try this later on.. Also how should I fomat the input for the turns ratio on the center tapped, it is not the same as others... should I use forwar slashes?  30/3/3  colons will  not work. Or do I have to just put a single number?

[jrshedden]

Hi,

Its just one number. You only have one secondary which is always halved by the center tap. 2 is twice the primary. 0.5 would be half the primary (each side of the center tap would be half that or 0.25 the primary). You could have more than one ration if you had more than one secondary, but that isn't the case. It's one winding with a tap in the middle.

Good Luck,

Jim S.