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Well, I’m going to receive a package from Electronic Goldmine with a bag of 800 ferrite beads.  They’re made by Fair-Rite, type 2643000801, which is type 43 ferrite material.  This is a medium mu material, for frequencies in the 100 to 300 MHz range. But type 43 works okay for JTs as long as there are a few more turns; enough to have about 100 uH inductance.

I’m going to try making a Joule Thief (JT) with a coil made with one of these beads.  I’m not sure if I can wind enough turns on this small bead to make a decent JT.  I’m hoping the coil will have a few tens of microhenrys of inductance.  I may have to use two beads together (see below).  Whatever the case I will have a lot of fun experimenting.

If this doesn’t work good, I will have over 700 ferrite beads to give away or sell.  Or put one on every wire to or from a PC board to cut down on radio frequency interference.

Another experiment I did quite a while ago was to connect two small ferrite toroids together with a link loop. A single toroid didn’t have enough room in the middle for the number of turns I needed. I threaded a single length of wire through two toroid cores and connected the ends together. This linked both cores together electromagnetically; whatever was in one core was tightly coupled to the other core. This could work for these ferrite beads. The small hole has to still have enough room for the turns of wire for each of two windings. That means fine wire.

Another one of my experiments comes to mind. One time I had some toroid cores that were not high mu. To increase the inductance, I stacked two cores, one on top of the other. Each winding was wound through both cores. I have so many beads that I could stack 3, 4 or even more to give more inductance, as long as I can get the wires through all of the cores. One thing I found out about Fair-rite cores is that the last digit tells if the core has been polished to remove sharp edges. If it’s 1, that means it is not polished; if it’s 2 then the core has been polished and there should be no rough edges. These beads are unpolished so they may have sharp edges that could damage the wires. I will have to use a deburrer to smooth the edges of the holes.

I bought a few other items along with the beads. I think these should keep me entertained for awhile.

Update Oct 16 – The beads and other parts arrived. The box of beads is quite heavy, as should be expected of something made of glass and metal.

I wound 8 turns of 30 AWG magnet wire through the center hole with room to spare. The length of the wire was 8-1/2 inches, the same as the width of a sheet of letter size paper. The inductance measured 98 microhenrys, which is just right for a JT. I have to get 8 turns of 3 lengths of 30 AWG wire in the hole. What i’m concerned about is the very sharp edges where the wire enters and leaves the hole. I tried two lengths of 28 AWG and one length of 32 AWG enameled wire, each 8.5 inches long. I could barely get 7 turns on the bead, but some of the enamel got scraped off by the sharp edges. Even so, the windings measured 102 uH, which is great. I think it should hold three lengths of 30 AWG, all 8 turns.

Update Oct 21 – I thought it would be best if I got rid of the sharp edges around the hole. I tried sandpaper by cutting a small strip and rolling it into a spiral that fit into the hole. It took off a small amount of the sharpness, but I think it would take too long to do, and the sandpaper got dulled quickly. I think I will try a diamond sanding block to see if it’s better and faster.

I’m not having much success with the diamond sanding block. The little bumps don’t want to go into the holes.

Update Oct 25 – I was in a store with a crafts dept, and was looking at some tools. I saw a tool called a bead reamer. It looks just like a round file with a sharp point, but instead of fine grooves, it was smooth and covered with what looked like diamond particles. The package said nothing about diamonds or what the material was. But I knew that beads are made of glass, so it had to be something that could grind glass.

I bought one and tried it on one of the ferrite beads (it was less than 4 dollars US). My fingers turned brown as the reamer took off the sharp edges of both the hole and the outside ends. It worked good, my only complaint is that I have to do the work by hand.

It will do the job for a few beads, but I don’t want to spend a lot of time doing this. I saw a project online on how to build a ball mill out of some wood, a length of 4 inch ID ABS pipe, rubber end caps, three ball bearings, and a small DC motor with a gear head that turns ten or so RPM. I could put a handful of beads into the container and let it run for several hours or longer, until the edges of the beads smooth out. But I’m not sure this will do anything to the sharp edges of the holes.

I found some diamond bead reamers on eBay, and I ordered a few of them. One of the bits looks like a cone, which should make it easier to take the sharp edge off the hole. They will be shipped from China, so it could take several weeks to get here.

Update Nov 12 – I received the diamond coated reamers today and they work okay for taking the sharp edges off the beads. But it may take a few minutes to do a single bead, so it will take me a very long time to do a hundred or more.

I’ve been getting close to finding a  motor to use as a generator for a hand cranked flashlight.  I found one a few months ago, which even included a crank. But the crank was small and hard on the fingers.

This one from Electronic Goldmine (apparently they’re sold out) has a motor and gearbox, with a shaft for a crank.  The shaft has a flat for mounting a crank with a setscrew (see photo).

I don’t have such a crank so I used a mini vise grip for a makeshift crank.  With the 1 watt white LED connected to the two contacts (white disk with wires), I can crank at a reasonable speed and get a nice amount of light output.  The LED gets barely warm, which means to me that it’s not getting a full watt of power from the generator.  But it’s enough to light the LED and use as a flashlight.  A better and lighter crank might help to increase the output.

I checked Goldmine website and couldn’t find any of the ones I bought. The gearbox makes it much easier to crank. But a small wheel from a caster might be used. The motor can be mounted so the shaft is pressed against the wheel and driven by friction. The wheel is then spun manually. The size of the wheel determines how easy it is to spin. It helps if the shaft has splines or is not smooth, so it doesn’t slip when the wheel turns.

I have also had some success with rubbing the shaft on a rubber or non-slip surface. The best example of this is a bicycle light dynamo. A dynamo (or stepping motor) will generate AC, which has to be rectified to make DC. But it can be driven in either direction. So a back and forth motion on a soft surface will drive a LED, if a 1000 if or more filter capacitor is across the LED, and rectifier or full wave bridge rectifier is used.

Another way of generating AC is to use the head positioning stepper motor from a CD drive. These have a shaft with a spiral groove in it. They will light a LED when the shaft is spun by rubbing on a bike tire or other similar surface. It’s not difficult to light a LED brightly with any small motor.

I have also had good results using a stepper motor from an ink jet printer. These drive the print head and sheet feeder. Stepper motors from other devices such as CD drives work, too. I found a YouTube video where a guy gets 10 plus watts from his hand crank generator with a stepper motor, rectifier, filter capacitor and control box. This is used to charge a cell phone. He has to crank it fast to get the full 11 watts, so a more realistic and easily done output would be 5 to 6 watts at 5 volts, which is about what a cell phone charger puts out.

One problem with these chargers is they require you to hold them with both hands and crank continually for a long time. The generator should be mounted (or mountable with a clamp) to a stable object (like the edge of a table or workbench) so that it can be cranked with one hand and leave the other hand free to do other things. A good way of mounting odd shapes is to use a hose clamp. These could be small or as big as a radiator hose clamp.

I finished reading this book about Admiral Hyman Rickover, father of naval nuclear propulsion, and about the deadly reactor accident that took the lives of the only three people to die this way in the U.S. The author is Todd Tucker.

Up until reading this book I had read only anecdotally about the nuclear accident at the facility near Idaho Falls, Idaho, on Jan 3, 1961.  This book goes into occasionally gruesome details to explain what most likely happened, contrary to the often claimed murder/suicide.

A large part of this book is devoted to Adm. Hyman Rickover, and his criticisms of just about everything, including nuclear power.  He managed to get the U.S. Navy submarine fleet under nuclear power.  Despite his shortcomings and habit of irritating people, he truly was an amazing man.

I recommend Atomic America as a history and biography of events and people in nuclear power.

Another book I finished recently is The Great Transition by L. Brown, et. al. It is about the transition from fossil fuels to renewable fuels like solar and wind. This isn’t the first book of his that I’ve read. In all fairness I have to say this book is one-sided. They talk about the advantages of renewables, but fail to mention their drawbacks. They discuss nuclear power, and I’m afraid it doesn’t sound optimistic. They point out the long construction times, excessive cost overruns, and unpopularity of nuclear power. Environmentalists, NIMBYs, and spent fuel disposal issues, too. It doesn’t look like nuclear power has a future.