I am referring to this page:

http://www.allaboutcircuits.com/vol_6/chpt_4/3.html

which is about building your own transformer.

The directions say to wrap two long bars of steel with electrical tape. Then wrap hundreds of turns of magnet wire around the long bars, and then connect them all together.

My question: is this transformer suppose to share the same core? According to the directions it seems that this is not that case b/c you are supposed to wrap the long bars in tape, thus insulating the cores of each part of the transformer. Also the schematic diagram doesn't show that it shares the same core.

 

They should be (magnetically) connected by the steel bolts. Therefore the 4 pieces of steel will function as 1 core.

You should be able to lower the magnetic reluctance if you leave the tape off the end of the steel bar (where it touches another bar). But I don't think this would have a huge effect.

 

You could do it a couple of other ways as well. Wrap one iron bar with tape then put a layer of turns of the wire on the bar. Then put another layer of tape over the first coil then wrap another layer of turns on top of that.

Another interesting experiment is to make only one long coil on the bar, then tap off the coil at calculated intervals. You will then have made an "autotransformer". The voltages produced will be in proportion to the turns ratio at each tap to the overall number of turns.

Have fun
Dan H

 

Great, thanks for the advice.