DIY transformer ...

[DeepCut]

Hi all.

I need to make my own (simple) transformer.

I have a ferrite-ring core, i have 18 turns for the primary and 6 for the secondary.

When i apply my AC voltage to the primary it shorts out immediately.

I have tried putting a resistor as a load on the secondary, i have also tried putting a tiny bulb as a load on the secondary.

In both cases, when the power is applied it still shorts out.

What am i missing please ?


Gary.

[z.monkey]

You need to get your primary side impedance up.  Take an ohm meter and measure the primary.  The resistance is probably so small it looks like a short to the AC mains, and you blow the fuse.  Its not a good idea to start your transformer experimentation using the AC mains.  There is a frightful amount of power available there.  Get an isolation transformer, or even better get an inverter that you can run on a battery so you don't electrocute yourself...

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Thanks very much z

I'm not using the mains i'm using the unrectified output from my replicatoin of Tom's device :

http://www.overunity.com/index.php?topic=9999.0

The resistance of the primary at the moment is only 2.9 ohms.

So i'll just wind some more turns, what would you recommend as a minimum resistance so i can calculate my coil length ?


Gary.

[z.monkey]

Substitute a resistor for the transformer, and see how much current is coming out of your circuit.  Put a 1 Kohm resistor on there and see if your voltage is drooping compared to an open circuit.  Then give it more or less resistance to see how much of a load you can drive...

Then when you know how much current is available you can figure out how many turns the primary needs.  Extrapolate the ohms per winding from your current coil.  Then take desired impedance divided by the ohms per winding, and the product is the number of turns...

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Thanks again z.

Doing it now


Gary.