I bought some Jameco inductors, among them was Jameco Part No. 371215, which was a closeout sale of $.49 each. Their picture shows it as uncovered wire, but all of the ones I got had a black heat shrink tubing around the circumference. The wire diameter was 24 mils, or about 23 AWG when the enamel insulation is removed..
I measured one and it was 475 uH. I cut off the HS tubing leaving the bare wires. The winding was more than one layer, so I started unwinding the turns, with the objective to leave a single layer that was at least 100 uH. I removed about a meter of wire and left a single layer. This layer was 64 turns, 0.078 ohm DC resistance, and measured 150 uH.
The core was painted yellow with a white end. The core measured 0.81 inch O.D., 0.45 inch I.D., and 0.265 inch high. I believe this is an iron core, mainly because it has low permeability. I don’t remember ever seeing a ferrite core painted yellow. The data sheet said ferrite core, and the core is from Core Technology and is a TC80-26B. I could not find any information online for this company or product. I strongly suspect that they mistakenly put the word ferrite in the data sheet. I did find this at surplussales.com which says that the Micrometals yellow-white iron powder core is 26 mix, which is consistent with the datasheet.
The price seemed reasonable. The toroid is a bit large for a Joule Thief, but it’s easy to work with, and makes winding a second feedback winding easy. It could hold more turns and with two more windings could be used for a higher voltage DC to DC converter.
Since it was a closeout sale, they may no longer stock these when they have sold out. However they have various similar inductors that look like they use the same core. For many experimenters a 220 uH, 330 uH or similar would be just as good for a JT, and it will probably have heavier wire, which keeps the DC resistance low.
Another different inductor
I also bought some of these inductors in their closeout sale. These are larger than the first inductor, but the number of turns is less so the inductance is 180 uH. These also use the yellow – white core. The number of turns is 44, and the wire size is 35 mils or 20 AWG when the insulation is taken into account.
I have tried to make a Joule Thief (JT)for a long time. I have switched wire config,components and nothing seemed to work. I have purchased half dozen ferrite toroid from Digi-Key. Using telephone wire to wrap the toroids. All of my components are good. I thinking my toroid are filter and not transformer type, which I didn’t know there was a difference. Looking for info on where to get the right toroid and where or what I doing wrong. There is not that many components or config. Help and Thanks
I hope the pictures and pictorials in this link will help you. The flat spot on the body of the LED must be as shown.
Make sure you click on the picture more than once.
http://rustybolt.info/wordpress/?p=128