Insulated versus not insulated copper wire

Without more details it would be impossible to give you a definitive answer, but generally I would say yes - Insulated is fine/better.

Thank you so much.  If I remember, I will let you know how it worked out!

Great stuff. Thanks.

Is it possible that what you see as uninsulated wire is really wire that has an enamel insulating coating? This type of wire is used on transformers and inductors and looks like bare wire but in fact is quite well insulated. Here is a coil that I wound using enameled wire that may look uninsulated but really is insulated.

John

What is the material in that transformer?  Is it 52 mix?  Is that a transductor or a transformer?  What size core?  How many turns?  What inductance?  What SRF? Why did you array the coils separately as you have, rather than wrap the core with a twisted pair?  What potentials are you operating at?  If that is used in some kinda saturation-based gadget oscillator, what frequency does it operate at?

How you doin'?

I presume the turns-ratio is 1:1.  You can thread the last turn behind the penultimate turn to hold things together.

Hi Don,

It is a ferrite 0.5 inch core. The wire came out of a small transformer that I salvaged from an old computer switching supply. There are (2) 20 turn windings. If the windings are not arrayed properly the reason is ignorance. As far as winding it was very difficult with these old eyes. I was nearly permanently cross-eyed when I finally completed it. It is part of a Joule Thief circuit operating at 1.5 volts. I believe the frequency was about 45kHz.

John

Oh, John, I am fighting a bitter and fitful struggle against ignorance myself.  Pardon my tone, I am distracted by extraneous events.

Efficiency of your power supply, which you were brave to construct and to blog about, is easy to measure.  As you gain SPICE-fu, your switcher designs will become slicker-and-slicker.  Efficiency is the amount of desired output divided by total effort.  If you measure the potential and current you put into your circuit and take their product, that's your input.  The power going to the LEDs is the output.  Now, I think, from what I have read, that you can 'bifilar wind' the transformer if your potentials aren't greater than something like 42 V in the US.  Above another potential, you are obliged to wind it as you did, plus put insulating tape on the transformer core.  Inbetween, secondaries are typically wound first then tape, then the other wind.  3M is one manufacturer of appropriate tape.  I am told that if you have greater intimacy between your primary and secondary, you can exploit capacitive coupling as well as magnetic coupling.  Bifilar and trifilar winds are preferred due to their analytical simplicity in most situations.  Another thing, when you wind it your way, you can use square magnet wire if you want, it confers a slight advantage.  In high-frequency situations, litzendraht wire is the conductor of choice.

You use a power drill (battery powered, on slow mode, wear leather gloves)`to twist the magnet wire together before winding the resultant twisted-pair upon the core. If you are as crazy as I am you have magnet wire with different-colored enamel.

If doing it this way yields a measurable increase in efficiency, it may be worth the trouble.  Might be an interesting experiment to conduct, upon your return to the bat-cave.

Note that when you add windings to a core, you are increasing your B over an area, rather than a line.  So if your twenty turns yields N quatloos of inductance, putting forty turns upon the same core yields 4*N quatloos of inductance.  Since you paid for a finite number of magnetic domains when you bought your core, saturation in the latter situation would come proportionately sooner.

Apologies to Margie for hijacking your thread.

Thanks Don as always for the great input. I will have to give your suggestions a try. My design was very inefficient. I should have renamed it the Joule Pit but it worked.

John