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Mr Lester J Hendershot's magnetic generator.

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  • David G Dawson
    replied
    Hendershot Capacitor Build

    Hendershot Capacitor Build:
    Here are some pics of my build process.
    This was the choice of caps I had.
    The one with the plastic cover was out of a Blaupumkt colour TV and knew it was damaged as the aluminium container had split but used this as an example of what was inside.



    Chose this one as it appeared to suit the bill nicely as it was 4" in length - note the ruler at right hand side.
    Removed the top with a small hacksaw and immediately saw that it was centralised in the big can by tar and so had to heat to remove but was much easier then expected.
    The tar simply came away once cut off with the first paper wind.
    Note the different sizes and the voltage ratings and my choice was the higher voltage but the difference was the huge gap inside.



    This is the aluminium foil after cleaning which was also simply done under a running tap using a kitchen scourer but gently.
    The cap as Hendershot made had two ends 1" apart at the centre and this is showing how I joined contacts to the cap foil by using pie dish 0.1mm aluminium and used it bent over with the cap foil inside the bend and simply poked a sharp scriber through many times to make contact and this appears to have worked well and is similar to what the manufacturer actually does.
    Capacitor value was close to the 7,800pF that Hendershot achieved but note here the length just happened to be just over 182" and all I had to do was cut in half to get the 91" required.



    Final shot of the finished product and you can see the two cap leadouts at rhs unit.
    The two transformers used here are also from the Blaupunkt and are horizontal driver types (had two) which would be directly equivalent to what Lester was using.
    My 'resonator' here is a 4 volt Multivibrator and was the setup that accidentally gave an 11kv spark due to a loose and sparking joint.
    However was not able to make the unit resonate.
    300 to 500 Watt output and 43khz gets a mention.



    Hope this helps in some way and was fun to build and mess with but had to go on to better possibilities which I am currently working on.
    The 'resonator' is my only problem here and have not come up with one that can actually induce a voltage into the twin coils.
    A great learning experience.
    Good luck with your builds.

    Smokey
    Last edited by David G Dawson; 01-18-2015, 02:14 AM. Reason: Picture size

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  • thx1138
    replied
    Professor Tinkerer: I've seen some Hendershot schematics that show the capcoil cap connections similar to what you show but I haven't spent any time with them yet. I may get back to that later.

    I've finished my build except for the capcoil caps. I thought I would do some testing while I think about those capacitors. The testing has shown me a couple of things of interest.

    I'm using a 120V, 60Hz variac to feed variable voltage power into the circuit like the J. G. Gallimore schematic shows as a startup mechanism on the right side of the ringer coils.

    Following the idea that someone posted that the capcoils were just eye candy to distract from the true functioning of the device I used no capacitor, 1.3uF and 7.8nF off the shelf capacitors in my tests while taking readings at 30, 60, 90, and 120 volts and different spacings of 3/4" to 0" from the ringer coils to the magnetron armature and with the armature removed and the coils even with the magnet poles and inside the magnet poles.

    The capacitors definitely make a difference but I didn't see any marked improvement with them. I'm thinking a may need much higher frequency AC for my testing. Considering Lester's relationship with the air force and the fact that the magnet is a magnetron magnet, I'm thinking 400Hz might be better - that being the frequency for most aviation power. But I'm not sure how to build a variable voltage, variable frequency, pure sine wave AC power supply. It's one of the things I'm looking into because the commercial units I've seen are in the $1000s. I have a function generator but it is far too weak to use for any testing.

    Noticing that the ringer coils had a wider side-to-side spacing on the one photo of the working Hendershot device and all other photos I've seen (Aho, Skilling, and Mark Hendershot), I also varied that spacing and found that the ringer coils need the wider spacing. They were shown where the their cores were about half way between the center of the magnet and the outside poles. That setup gave immediate results of about 20% increase in throughput. Moving them out to a position centered on the end poles of the magnet gave slightly more improvement - 1 to 2% more.

    I tried different ringer coil mounting materials as well. The coil cores have tapped holes in one end and I mount them to the adjustment sled with stainless steel non-magnetic screws through the mounting material into those threaded holes. I suspected that using the permalloy mount that came with the coils would be the best. But that was wrong. Changing from permalloy to aluminum mounting material gave another 20% improvement. I think that's because the permalloy mount was sucking magnetic flux out of the coil cores so it wasn't inside the portion wound with wire. Changing the mounting material to a non-magnetic material left more magnetic flux in the permalloy cores so gave more output. I also tried perf-board and that gave another 1 to 2% improvement. I think that's because the flux into the aluminum was setting up eddy currents.

    I don't have a very good method of making the ringer coil to magnetron armature adjustment so those 1 - 2 % improvements may just be adjustment differences in the armature gap and could be discounted.

    I've only tried one schematic so far and don't have anything useable yet. But I will keep plugging along.

    Thinking about the capcoil caps and having destroyed too many caps looking for paper, I've decided to take another route. In one of the web sites I found on dielectric constants of various materials they say that Teflon has the same dielectric constant as dry paper - 2.0. Interestingly, that's the same as paraffin also. So I'm thinking that as long as the Teflon film is the same size and thickness as the paper it should work okay. I could not find the original Pyramid combined cap but I did find individual Pyramid caps on ebay and took them apart. The paper is 0.003" thick measured with a vernier micrometer after letting them dry for a month. So I guess I'll try the same thickness Teflon which is plentiful. Opinions anyone?

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  • ProfessorTinkerer
    replied
    Extrapolation

    I was recently having a discussion with the chief engineer where I am employed about CVTs or Constant Voltage Transformers. He sketched out his rendition on the blackboard and like the pic here, it had three windings, except in his drawing, the center gap was closed with the 'resonance' winding wound on it, connected to the AC capacitor. Then, a Ta Da moment happened. Look familiar? Sure, the H-shot cap/coil assembly isn't necessarily 'ferro-resonant' (no real iron mass), but the topology is very similar. Could we make a guess that the H-shot cap/coils are really CVTs, only at a much higher frequency? The cylindrical cap and the outer winding serve as the resonance feedback for the other three windings? Couldn't help but notice the similarity, as I had never noticed this aspect before. Food for thought.

    Attached Files

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  • thx1138
    replied
    Originally posted by ProfessorTinkerer View Post
    thx1138: I think I might have misinterpreted your question. If you mean the kraft paper that is the initial layer on the stainless steel cylinder, I always just used kraft paper available from hobby or craft stores like Michael's or Hobby Lobby. One turn, secured with a tiny piece of tape. Last time, I think I actually secured it with the hot paraffin wax used to seal them up.
    What I've read said the layer next to the inner metal former was "heavy white paper". I was asking about the actual capacitor dielectric paper that goes between the foils. From what I understand it is a very pure cellulose that is specially dried. Everything I've seen at the hobby stores is recycled paper so I'm guessing it could have just about anything in it.

    I have a friend who built asphalt highways his whole life. I mentioned to him that I had seen an article about using recycled tires in the asphalt and he replied that it sounded good but it was kind of like making an angle food cake with 10 lbs of onions because you already had the onions on hand - it just didn't work. I look at this in same way - the wrong materials are going to end up with a bad result.

    I've found quite a bit about the capacitor paper on the internet but they are all industrial sources. I read that Hendershot had problems getting the electrolyte out of the paper so I've been trying to find new capacitor paper to avoid that problem. But I guess I'll have to open up some more capacitors.

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  • ProfessorTinkerer
    replied
    thx1138: I think I might have misinterpreted your question. If you mean the kraft paper that is the initial layer on the stainless steel cylinder, I always just used kraft paper available from hobby or craft stores like Michael's or Hobby Lobby. One turn, secured with a tiny piece of tape. Last time, I think I actually secured it with the hot paraffin wax used to seal them up.

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  • ProfessorTinkerer
    replied
    Well, with one build I did, I used the unrolled wrap of AC starter capacitors. Finding the right length (not too short) was iffy, but I finally did find two the same. They weren't as stable as this last pair, which were actually made from sample wraps of photoflash capacitors. I used to be an engineer at a photography flash manufacturer and could obtain sample caps from several vendors. Our main supplier just sent me rolls of paper and foil complete with terminal tabs, so I was able to cut them to size. It still wasn't any fun and took a tremendous amount of planning and effort.

    In answer to your question, no not really. I am of the opinion now after years of pursuing this riddle, that some aspects of the design are inconsequential providing the results yield the correct capacitance values. The different variants of the dielectric only seem to alter the overall thickness of the foil/paper wrap and require that the tension applied be altered to achieve this goal. But, I could be wrong. I still have yet to see any results from all the effort.

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  • thx1138
    replied
    Originally posted by ProfessorTinkerer View Post
    Very interesting. Obvious next question: Since they are a complementary pair, would you be willing to part with one of them?
    They have opposite polarities. One side is south pole on the ends and north pole in the center and the other is north pole on the ends and south in the center.

    I won't part with one until I have tested with both and maybe not even then. If I can get this device to work with both pieces I'll look into tying the two builds together to see if I can get that will work.

    BTW, I'm having problems finding pure 30# Kraft paper for the capacitors in the capcoil. Any suggestions?

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  • ProfessorTinkerer
    replied
    Very interesting. Obvious next question: Since they are a complementary pair, would you be willing to part with one of them?

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  • thx1138
    replied
    Originally posted by ProfessorTinkerer View Post
    thx1138: Can I ask where in the world did you come by that magnetron magnet? Aside from archive photos from across the pond, I haven't had any success in locating a physical one. Would love to know.
    eBay, believe it or not. It was from Poland and said to come out of a Russian radar which matches with the Wikipedia article - 3rd picture exactly matches what I received.
    Cavity magnetron - Wikipedia, the free encyclopedia

    I asked if he had more but the answer was no. He said he might be able to get more but they would be expensive. You might contact him.
    Soviet Radar Tube Magnetron MI 189W MI 189V МИ 189В | eBay

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  • ProfessorTinkerer
    replied
    Greetings. Professor Tinkerer here. New to this forum, but not the Hendershot. Been researching it since the first time I saw Skilling's article in 1985.
    thx1138: Can I ask where in the world did you come by that magnetron magnet? Aside from archive photos from across the pond, I haven't had any success in locating a physical one. Would love to know.

    I have replicated this device three times thus far, with no success, but I have gained some insight into it's construction. There is a detail left out, which is typically the case in these unknown areas. Upon finding this forum on the net, I recently pulled out the last rendition from the mothballs and checked the cylinder cap values. It has been in storage since 2008. I was surprised to discover that they both measured exactly the same value: 9,340pF. Just a 'for what it's worth' I suppose.

    Like to hear about the magnet, though. Signing off.....

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  • dragon
    replied
    Hi Smokey, thanks for the kind words. I used 500 ohm coils also, tried many others that didn't work at all or worked poorly. One thing to point out that I don't think I've ever seen posted is the fact that the coil wires are also connected to the cores. I don't know where the close up picture of the buzzer came from but if you look closely you'll see the wire coming from the coil to the buzzer is connected to the core and coil. Once I saw that I realized they were shorting the coils through the core when the bar was attracted - once shorted it de energized the coils, you get a spike as it's pulled off the core by the magnets.

    I don't remember the final capacitance of the wound cap, I could never get them perfectly matched - lots of screwing around with them - as close as I could get them to the stated capacitance. I tried aluminum, thin iron sheet and copper - the aluminum seemed to give the best results but its really hard to say because they all seemed to work to varying degrees - none of which I would consider completely successful.

    Like you I've moved on to other projects but maybe someday I pull it from the shelf, dust it off and ponder what I may have missed...

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  • David G Dawson
    replied
    Hendershot Detail

    Dragon, thx1138,
    Some good exchanges between you two and most impressed.
    Dragon, an excellent build and one which works even if not full time.
    Good to see someone else has built the capacitors as my unit is fully completed, not working and need to change the capacitor former to a soft Iron.
    Also good that you are using the original Aho schematic.

    The twin coil bell ringers, I now have 11 in my collection, are all of 500 ohms each and have been able to induce voltage up to about 3.5v simply by moving a magnet along their length.
    The reason for buying these is also for the Dollard 'Cosmic Ray Detector' (CRD) but also for a Tesla Mechanical Oscillator.
    Still not able to get the 'resonator' to work as per the Hendershot detail and still working on that.
    thx1138 as been most helpful in the realisation that the Magnet is of the 3 pole Radar type.

    Not happy with using a laminated power transformer due to frequency limitations for the 5:1 step up and am using two horizontal deflection types out of old Blaupunkts - luckily, I had two.
    There is a picture somehwere of these but probably back at the other Forum.
    These are of the Ferrite type with many windings and are adjustable with respect to reluctance.
    Although, what Lester is using appears to be of the general laminated form but there would be some design feature incorporated that would make it more appealing for the higher frequency used in TV deflection circuits up to 15 Khz.
    This may need to be researched in some detail.

    Building the Hendershot Generator in itself was a lesson in construction ability and technique in particular with the basketweave coils and home-made capacitor and will not ever regret not building.
    Still here waiting for another approach but too time limited as I am into a Steven Mark TPU but of a contractive type and not his expansive.

    Dragon,
    I should be asking some questions here like what was the final capacitance value of your caps and what did you use as the former?
    What did you actually use as the 'resonator' and what voltage were you able to achieve out of the twin coils?
    I didn't see a 'resonator' in your picture.
    Thanks.

    All the best with your builds.

    Smokey

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  • dragon
    replied
    Originally posted by morpher44 View Post
    I've stumbled upon various interesting youtube videos where people show they
    can make very effective batteries using carbon and Aluminium.
    Now Hendershot's cylinders were Aluminium (and possibly the magnetic kind).
    Hendershot was also rumored to have used carbon rods in his design.
    We also know he hand-made his capacitor, by dismantling a perfectly good capacitor, removing the oil, cutting the foil a very special way, to specific dimensions with 3-plates rolled up around the cylinder.

    Now, it occurs to me that not only do carbon and aluminium produce a very nice galvanic battery, there is also potential here for thermoelectric power generation.

    Imagine carbon doped inside a hand-made capacitor.
    Now imagine high-voltage ARCs between the plates and thru the carbon, with high-intensity HEAT at the atomic level in this carbon-aluminium mix.

    This could explain why Hendershot's hand made capacitors seem to be damaged inside when you open them.

    The power from this reaction may not be the entire story, but it might be useful in starting the machine w/o the need or appearance of manufactured batteries.

    Anyway, I think this is an interesting area of research to pursue with respect to reverse engineering Hendershot.
    It does seem to require an "initial charge" to excite the unit into operation which requires a reasonable current flow and would justify your theory of a galvanic structure to initiate a charged state. I've never achieved a self sustaining operation but once the caps are charged the whole thing pulses or vibrates. The best I could achieve on the output was lighting a 40 watt bulb at around 30 hz with a very noticeable pulsing both visually and physically. It would run about 30 seconds as the caps transferred energy back and forth until the energy was depleted.

    The only schematic that would function like this was the original Aho circuit. The "buzzer" is arranged as Thx stated where both ends are similar poles. This tends to initiate a very high voltage spike upon break.

    Once you understand his original 3 coil oscillator you can see what he was trying to achieve with other units. Dr Stiffler created a similar 3 coil PSEC - both of which take an enormous amount of patience to set up.

    A good understanding of early microphones and pick up coils is quite helpful also - particularly the balanced armature units also known as the sound powered systems that are still in use today. You can still find the old sound powered headphones on ebay used by the Navy in ships to assure communications throughout the ship if a power failure was to occur. You'll notice one of the pictures of Hendershot standing by one of his devices used an Ader microphone to communicate signals into the device.

    I've since moved on to other projects but I must say it was a fun and very challenging experience working with the mans ideas. Truly a genius of his time !
    Last edited by dragon; 10-24-2014, 12:05 AM.

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  • thx1138
    replied
    Seebeck Effect

    The Seebeck Effect is what makes thermocouples work. My first experience with one was the thermocouple on a gas water heater. The end of the thermocouple is positioned in the flame of the pilot light. The main gas valve to the heating burner detects the presence or absence of the electricity from the thermocouple. If the voltage from the thermocouple is present at the valve controller it allows the feed to the main burner to open and thus heat the water. If the voltage is not present the controller keeps the main supply to the burner turned off since there is no pilot light to light it. When the thermocouple fails the main burner will not light because, although there is a pilot light flame, the controller doesn't sense it. That's what happened to me and what got me to look into it.

    Thermocouples can be made from any two dissimilar conductors. The water heater thermocouple is made from copper and iron. The key is the separation between the ends where one end is hot and the other is cool. That heat gradient between the ends is what sets up the electric potential. They can be engineered for just about any particular heat range needed depending on the materials used.

    I haven't seen any documentation on carbon being used in the Hendershot device. But I guess we could consider the carbon in the metal coffee can to be the source.

    I don't see it working that way though because as soon as there is a short in the capacitor part of the capcoil it is no longer a capacitor and therefore no longer a tank circuit. So it would just be a shorted coil.

    What would be nice is to find a thermocouple that would work between 70F and 120F. I could then harness the power of the gradient between the attic of my house and the interior. I've never seen anything that would work on that small of a gradient though.

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  • morpher44
    replied
    Carbon and Aluminium continued...

    https://www.youtube.com/watch?v=k9Zbmwf5uEQ

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