Hendershot Replications

[dragon]

I believe the transformers act as a magnetically controlled bi-directional diode. When current flows through one side the other side can only pass current in one direction which allows the caps to charge. Once the current slows from that direction the other side becomes active creating a directional flow opposite to the first thus charging the opposite caps.

Very similar to the magnetic amplifiers, we are "gating" the directional flow like a transistor but with the ability to reverse directions. Tesla's patent for converting AC to DC explains the phenomenon reasonably well ( 413,353 ).

Magnetic amplifiers operated very similar to the vacuum tubes of the day and can perform the same function.

[thx1138]

I believe the transformers act as a magnetically controlled bi-directional diode. When current flows through one side the other side can only pass current in one direction which allows the caps to charge. Once the current slows from that direction the other side becomes active creating a directional flow opposite to the first thus charging the opposite caps.

Very similar to the magnetic amplifiers, we are "gating" the directional flow like a transistor but with the ability to reverse directions. Tesla's patent for converting AC to DC explains the phenomenon reasonably well ( 413,353 ).

Magnetic amplifiers operated very similar to the vacuum tubes of the day and can perform the same function.

I'm thinking along the same lines but, being a digital guy, I'm really struggling with the analog AC stuff.

That's why I'm asking about the "vertical oscillator type" transformers. I would like to do a build but I'm pretty sure it isn't going to work with regular 5:1 power transformers. That's why I'm trying to identify the differences.

A little redrawing of the Tesla patent Figure 6 using one magnet with one pole in the center and the end poles being opposite polarity yields pretty much the Hendershot buzzer.

[dragon]

I'm thinking along the same lines but, being a digital guy, I'm really struggling with the analog AC stuff.

That's why I'm asking about the "vertical oscillator type" transformers. I would like to do a build but I'm pretty sure it isn't going to work with regular 5:1 power transformers. That's why I'm trying to identify the differences.

A little redrawing of the Tesla patent Figure 6 using one magnet with one pole in the center and the end poles being opposite polarity yields pretty much the Hendershot buzzer.

I have a difficult time visualizing electrical/current flow as well - we all have similar but different theory on how it works - when we see something that works our theory is proven or altered yet still remains theory... I don't believe anyone truly understands...

In an attempt to create a more controllable "buzzer" I built a motorized monopole coil set, similar to Hendershots arrangement. Shown in the attachment. This produces 1200 volts of pulsed pumping action. Basically all it's doing is disturbing the north pole and allowing it to relax naturally.

[dragon]

One other note, you can use any 5:1 transformers - I've tried 3 different matched pairs of different size and current rating - they all function the same.

You can take any transformer as a test unit, connect one coil to a battery and LED and use a separate battery on the other coil and visualize how altering the current flow will increase or decrease the LED's intensity. If you have a function generator set to low frequency ( 10 hz or so ) you'll notice how the flow change either aids in lighting the bulb or hinders the flow.

When the light is low or off, current will flow freely into the battery that is lighting the bulb from an external source acting like a diode. At the point where the cyclic input changes it will give you battery power plus energy transferred through the transformer caused by the change - amplified output as it were.

[thx1138]

Here are two links I found to TV blocking oscillators circuits. I vaguely grasp the operation of vacuum tubes but have no experience at all with them.

Of course the Hendershot device has no switching device, tube or transistor, but I see some similarities. I was thinking of the feedback mechanism that the Hendershot generator must have somewhere when I saw this one so it might be relevant in that it generates a pulse that is high powered but short duration so the overall power of the feedback would be low. We don't have a resistor either but I'm wondering if we should look at one or more of the coils as supplying this resistance. This circuit doesn't make any note about the primary/secondary phasing.
Blocking Oscillator definition of Blocking Oscillator in the Free Online Encyclopedia.
But the transformer in that circuit looks like it would have 6 leads rather than 4.

This circuit is similar and the transformer only has four leads like is specified in the Hendershot docs. If we use the ARRL standard transformer wire color codes we can see somewhat where the wires go. This one does note that the secondary is 180 degrees out of phase with the primary.
ARRL:
Red - B+
Green - Control grid of vacuum tube
Blue - Plate (anode) of tube
Black - Ground or in this case the sync signal
THE SET blocking oscillator theory
There are notes in Mark Hendershot's From the Archives of Lester Hendershot on page 39 that tell where each colored wire connects.

@dragon: I don't really grasp how that phase change in the transformers would fit into your idea of the transformers as bidirectional diodes.

[dragon]

Just before vacuum tubes came into existence they were using magnetic amplifiers ( 1900's ) to do most of the functions the tubes would later do - 47 years later the transistor replaced all of it. Unfortunately, most of that technology was lost or buried. The transformer can actually do more than a big pile of modern components in a tidy little package.

Here is a good place to start...
Homemade Magnetic Amplifiers.

The Zen analogy comes to mind... like a cup overflowing we are full of our own ideas and teachings, in order to move forward we must first empty our cup...

[thx1138]

Just before vacuum tubes came into existence they were using magnetic amplifiers ( 1900's ) to do most of the functions the tubes would later do - 47 years later the transistor replaced all of it. Unfortunately, most of that technology was lost or buried. The transformer can actually do more than a big pile of modern components in a tidy little package.

I stumbled into MagAmps when I was researching Steven Mark's TPU. I didn't know enough then to understand them. Probably still don't. Need to do some experiments I guess. RE the TPU, the device on top of one of his versions with two toroid looking coils looked like a MagAmp to me.

Here is a good place to start...
Homemade Magnetic Amplifiers.

Many thanks. Looks like good experiments for me to do.

The Zen analogy comes to mind... like a cup overflowing we are full of our own ideas and teachings, in order to move forward we must first empty our cup...

Well, if you're in the process of emptying your cup please continue pouring it my way. I have no formal EE training so you might consider my cup nearly empty. I taught myself the digital stuff I know. Worked in software for +30 years starting with a Radio Shack Model I bought from the Greensheet. On the one hand, I don't know much but at least I recognize that. On the other hand, I don't have to "unlearn" much either.

Once I get a handle on the MagAmp I'll try reworking one of the blocking oscillator circuit schematics to use a MagAmp in place of the vacuum tube. Maybe that will fit into the Hendershot schematic somehow. Or at least my perception of it.

Interestingly, there are companies that still make MagAmps:
Butler Winding

[dragon]

I see the hendershot device as an early crystal radio. More so, 2 radio's back to back tuned 180 degrees out of phase. In addition, an amplifier and a way to communicate. Instead of speaking into the microphone to transmit a voice signal the device communicates with itself sending a signal back and forth between the radios. In essence 2 receiver/transmitters that echo the same signal over and over. Similar to a microphone in front of an amplifier where a single tone is input to the microphone the sound is amplified and sent back into the microphone - a feedback loop.... that annoying squeal.

In 1952 a set of plans ( very poorly done I should add ) from "Utility engines" describing their version of how it might work. Hendershot was quite angry about this and shut them down but later admitted it wasn't right but they were very close. The basics of this was a crystal radio to drive a small motor. The motor became the amplifier and feedback transmitter.

Interestingly enough, 2 years earlier in a book called "The boys book of crystal radios" was published and had the same crystal radio diagram that was published by Utility engines. Also interesting when you take that drawing and place the diagrams side by side it looks very similar to the hendershot device... Shown below...

I suspect that back in the 20's there were a lot of broadcasting stations that used sparkgap transmitters which would send a pretty healthy signal into the earth and make it reasonably easy to tune to a local broadcast with a fair amount of energy available. I don't know if there was any "trickery" going on with hendershot but it would have been easy to tune the coils to a local broadcast to get the coils in resonance then it was simply a matter of creating an amplified feedback loop.

His use of the dipole antenna/capacitor for the main tank was extremely creative but extraordinarily difficult to tune the pairs with any precision - for me anyway.

So, in ending... I gained an enormous amount of knowledge which led me in multiple directions from working with and researching the device but never managed to get it working as hendershot described as self sustaining.

[wings]

interesting the tuning effect with Ferrite Sleeve Loop Antennas antenna

somewhere in the internet: 1/2 "diameter rod 8" long may work best at ELF

why are positioned horizontal and not vertical like Hendershot ... are influenced by the frequencies of the Earth's magnetic flux or are tuned for Whistlers?

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

Ferrite Sleeve Loop Antennas— A DXer’s Guide

http://www.angelfire.com/electronic2...sign-Rev-A.pdf

search for "Experiments with a 7 1/2" FSL By Everett Sharp N8CNP "

[thx1138]

I see the hendershot device as an early crystal radio. More so, 2 radio's back to back tuned 180 degrees out of phase. In addition, an amplifier and a way to communicate. Instead of speaking into the microphone to transmit a voice signal the device communicates with itself sending a signal back and forth between the radios. In essence 2 receiver/transmitters that echo the same signal over and over. Similar to a microphone in front of an amplifier where a single tone is input to the microphone the sound is amplified and sent back into the microphone - a feedback loop.... that annoying squeal.

In 1952 a set of plans ( very poorly done I should add ) from "Utility engines" describing their version of how it might work. Hendershot was quite angry about this and shut them down but later admitted it wasn't right but they were very close. The basics of this was a crystal radio to drive a small motor. The motor became the amplifier and feedback transmitter.

Interestingly enough, 2 years earlier in a book called "The boys book of crystal radios" was published and had the same crystal radio diagram that was published by Utility engines. Also interesting when you take that drawing and place the diagrams side by side it looks very similar to the hendershot device... Shown below...

I suspect that back in the 20's there were a lot of broadcasting stations that used sparkgap transmitters which would send a pretty healthy signal into the earth and make it reasonably easy to tune to a local broadcast with a fair amount of energy available. I don't know if there was any "trickery" going on with hendershot but it would have been easy to tune the coils to a local broadcast to get the coils in resonance then it was simply a matter of creating an amplified feedback loop.

His use of the dipole antenna/capacitor for the main tank was extremely creative but extraordinarily difficult to tune the pairs with any precision - for me anyway.

So, in ending... I gained an enormous amount of knowledge which led me in multiple directions from working with and researching the device but never managed to get it working as hendershot described as self sustaining.

I see some similarities with the radio circuit you posted but the obvious difference is the earth grounds. I suppose we could consider that both the high voltage and low voltage sides being connected through the center common terminals of the 80/40uF capacitors make up a "virtual ground". It also occurs to me that Hendershot had access to military personnel at one time and if radio were involved it surely would have had some variable tuning capacitors. I haven't really seen anything that Hendershot worked with radio much.

I took a shot at fitting the Hendershot components into the series MagAmp circuit that was on the site at the link you shared above and it seems to me to be a very close fit with a couple of sticking points. The interesting thing about combining the two schematics is that the phasing of the Hendershot transformers can be worked out from how the components would be connected in the MagAmp schematic.

The first sticking point is that the output in the Aho and all of the other schematics connect to both the high and low voltage sides. I understand that the isolation of the two sides in the MagAmp circuit is a feature. What I'm not exactly sure about yet is whether the isolation of the two sides is a requirement. I don't think so as long as the magnetic flux bias occurs. And since we don't want a variable flux bias we don't need the variable resistor which, in the MagAmp circuit, just acts a variable voltage divider to modify the flux bias.

The other sticking point is to determine what is the oscillator. My first thought was that the magnet/armature/coils "buzzer" is the oscillator supplying the power and the cap/coil would be the battery, or rather batteries. But on second thought, and considering that the unit has to be charged to initiate the oscillation, the combination cap/coil could act as the oscillator since it is a standalone tank circuit and we could think of the buzzer as the battery in the MagAmp schematic. I'm still leaning toward the first option.

There are a couple of other items that cross over between the two circuits.

I mentioned in an earlier post that there must be feedback somewhere in the Hendershot circuit and the MagAmp supplies that.

Also the MagAmp circuit deals with transformer saturation and that might answer my question about what is special about vertical oscillator type transformers. The materials used in the laminations and construction methods both affect saturation.

Frequency seems to also play a roll in the transformer selection for the Hendershot Generator. I hypothesized at one time that the "vertical oscillator type" transformers specified might be from a radar display unit since the magnet appears to be from a radar magnetron and Hendershot had access to military equipment in the early days. But that's just a guess. A lot of military equipment runs at 400Hz rather than 60Hz to reduce transformer size and weight and especially so in aircraft. That will affect transformer efficiency as well which we need to be fairly high to get any useable power out of the magnet. Frequency is also part of the materials and construction mentioned earlier.

If you would be willing to revisit the project, I can do a write up on how the circuits match up. I've already done some drawings but they'll need some explanation.

[dragon]

Have you built any of the components?

[thx1138]

Have you built any of the components?

I have acquired most of the materials but haven't put them together because I got stuck on the magnet. I couldn't find any documentation on the strength or dimensions of the magnet so I stopped working on it.

I still need the 80/40 caps, telephone ringer coils, the pipe for the center of the cap/coils and associated Kraff paper, and hardware for making the ringer coils adjustable. Everything else I already have.

The transformers I have are standard power transformers so I may need to either rebuild them or replace them with vertical oscillator type. I'm going to use what I have first.

I have the magnetron magnet now and have made the armature for it and am looking into firing up the project again.

BTW, mentioning the ringer coils reminded me to mention that the spacing between the ringer coils is probably important because of how they relate to that center pole in the three pole magnetron magnet.

That's where I am right now.

[dragon]

If you've set up the mag amp then you've seen how it can allow current to flow or to block it. The battery and resistor side functions similar to the grid plate in a vacuum tube. Your simply saturating the core instead of blocking electrons. If you have the battery and resistor biasing the core so the light barely lights and put an AC source on the battery side ( function generator will work ) you'll see the light will go out on one half cycle and get very bright on the other half.

During the half cycle the current is blocked, when there is a capacitor in line - the cap will charge from the High frequency resonant coils - as it would if you were using a diode. When the other side is depleted the current stops flowing allowing the freshly charged cap to flow through the transformer and reverse biasing the opposite side allowing the other cap to charge.

Basically what you have is a mag amp being biased on both coils. Similar to a diode with a transistor to release the energy at the appropriate time... by using the transformer you actually get a bit of a boost as the change occurs.

Work and learn with what you have - you need to get there on your own - my words can guide you ( or confuse you ) but when you see whats going on first hand then you'll have the "aaahaaa" moment of understanding. That dear sir is only acquired from building and failing... unfortunately.

I was pretty obsessed with this at one point - building, re building, wiring and rewiring, try this and that... total frustration and ready to toss it all in the trash. Each time small successes from each failure brought me to a point where it would actually light a bulb for brief periods ( very brief ). After fusing around, tuning and retuning I made a realization that this obsession would only lead to a few tens of watts and had to put it on the shelf. What I learned from it, however, is priceless.

[morpher44]

similarities to armstrong, mag amps, magnetometer?

Hi Guys,
Interesting discussion about how Hendershot's circuit is similar to radio designs of the time. His upper coils on the cylinder are reminiscent of Armstrong's tickler coils. His deep understanding of how "basket-weave" and "honey-comb" coils leads me to conclude that he was definitely reading the "state-of-the-art" hobbiest magazines with respect o how to wind coils.

Recall though, that his original goal was to improve on the so called "inductance compass". So he probably was studying those designs, many of which you can find patents for using Google patent search.
He wasn't really thinking about radio or mag-amps.
He was thinking about how to "tweak" a compass to give a better reading relative to the Earth's magnetic poles.
He found he could make the compass SPIN -- rotate.
Now, what would make a compass SPIN?
The field around the compass must be spinning -- correct?
Further, this spin has to be DARN SLOW -- frequency-wise.
He first incorporated this "trick" into a little motor for his son's toy air plane.
He later went on to refine this idea and tried many things which eventually evolved into his so called fuelless generator.

The other thing that occurs to me while playing around with this stuff is that a coil and capacitor, just sitting there, will be DEAD -- completely DEAD -- unless you can somehow pull energy from the ambient surroundings,
or have a CHARGE build up per galvanic battery effect, or inductive pickup, or antenna reception, or something else that can be explained by present-day-physics.
Further, a magnet will SHAPE a field, or bend it - so as a component in the design they are like a GATE the bends the field into a controlled geometry. Nothing more. Magnets can also ADJUST the tuning -- mag-amp-wise -- so that you can approach resonance "better".
I think we pretty much understand what magnets do and they are very simple things. Yes you can put one near the coils of a buzzer and either make it buzz FASTER or SLOWER.
I therefore conclude the buzzer-bar-clapper arrangement is for tuning, yes, but down in the very low frequency range -- say 10 Hz to 80Hz. Buzzers are hard pressed to oscillate faster.
If you want a resonant circuit down that low, you must think power-supply design -- so the 5to1 transformers aren't unreasonable here.
Hendershot was rumored to have powered a TV set for his kids and a radio, as well as lights. Thus it must have be NEAR 60Hz (American standard), and he was probably tuning for that -- similar to the so called "Vibrator" circuits used to convert 12Volt car-battery voltages into high-voltage AC for Tube radios.
Those circuits used a relay-like device and just snapped the 12-volts back and forth into a step-up transformer.

Bottom line, though, is you need the energy coming from some place, and that is the true MYSTERY of Hendershot's device.
One picture has his device right next to the wall.
If behind that well you have the house-main cable, pick-up from that
would be easily achieved. This could even be mistakenly thought to be some mysterious earth-grid location as he moves his device around to see which wall it works best against. I hope he didn't make that mistake, but I could easily see someone making that mistake.

Another "clue" is that I had made this coil that happened to used pencils, nice little rods, for a basket weave coil. I got the idea of using a cassette recorder using a coil instead of a microphone for a "pick-up" so that I could hear the audio as the coil was working.
I was amazed to discover that certain areas of the coil produced a really "noisy" signal when I moved the recorder near those places.
Other areas of the coil were dead silent.
I found that the mystery was the graphite in certain pencils.
Some pencils were #2, and some were different.
Hence the graphite was introducing a wonderful NOISE into the system.
A sparky, rushing, white-noise sound. Fascinating.

Meanwhile, Hendershot's design also has elements of "fluxgate" magnetometer developed in the 1930s.
The magnetometer was patented very soon after Hendershot's device.
Hendershot's device, however, is a BIGGER-thing with power generation in mind, not a simple little sensor.

So, we have this interesting hybrid MIX of things that have been patented BEFORE and AFTER Hendershot.

[morpher44]

"fluxgate" magnetometer - motor?

An interesting design challenge would be to come up with an new sort of wiring for an electric motor, such that inside the motor is a magnetometer.

The motor, as it spins, is already creating a nice AC waveform - a needed ingredient for "fluxgate" magnetometers.
The motor, too, can have MAGNETs inside it for the creation of a magnetic field with ONE orientation.

The magnetometer will induce current when in the presence of a magnetic field, at certain orientations (not unlike how Hendershot's motor would only work when pointing certain compass directions).
If the induced current could be ADDED too the currents used to drive the motor, you have a situation where just placing the motor in a STRONG magnetic field will provide a positive feedback gain.
With a good capacitor, instead of a battery, you might be able to hold the voltages steady and harvest as well as provide power to the motor.

re: magnetometers.
Don't think "sensor". Why not go "bigger"? Much "bigger".