A Hand Cranked MagnetoGenerator

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Interesting links

I'll bet mine has a set of weak magnets. We were having a contest to see who could get the bulb to light the brightest, in the lab - that's where the 100 HZ came from. I imagine that they used some iron pole pieces for the magnet and it would lose flux over the years.

Sometime I'll have to hunt for it and see what some rare earth magnets can do.

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Greetings,

I'm trying to locate information on the hand crank magneto generator used in vintage phones:

how they were constructed what charge was produced and how was it used.

I tried Google but my query returned little.

rg

Loads of them on ebay, look for Ericsson or just do a search for magneto.

Plenty of references on the net as well, do a search on telephony and magneto.

I have one by me as I type, it is very similar to engine magnetos, just not made for high speeds and the hand crank gears the input speed up by about 3 times.

Peter

You should first look for antique telephones. I know of several dealers (yes, dealers) who sell such stuff, and they are members of the ATCA, Antique Telephone Collectors Ass'n. The last meeting I went to they had old porcelain "Bell System" signs for $400 to $1200, and I asked one guy who bought one how those prices were, and he said they were reasonbable. So don't expect to get a magneto for cheap. A decent wall telephone with a hand crank costs $200 on up, so figure out how much you wanna spend.

http://207.158.222.209/ericsson/links.htm some links to other tel websites

Ekkehart Willms website has some amazing items, more than just telephones. Like the Art Deco radio for $$$$$! I saw it at the last meeting, and it's awesome.(# R7 here

The generator puts out about 90VAC at about 20 Hz, depending on how fast it's cranked. It's bridged across the phone line and when cranked, a switch engages and connects the rotor to the line. Just a few magnets and a armature with wire and slip rings.

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I see that there is a lot of interest in this device. I was hoping to get an illustrated parts breakdown so that I can get a better understanding of whats going on when the crank is turned.

If anyone has one or know where I might view a print, I would appreciate the tip.

rg

My cat could give you more information that I can - sadly (and I still feel bad about it) I connected one lead from one of these to a metal plate, and the other lead to a saucepan of milk - cat stood on the plate and started drinking the milk - I wizzed the handle and he jumped

David - who doesn't feel bad though about all the local kids he talked > Greetings,

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Lot of pictures of old magnetos no drawings that I could find. Chances are there's an on-line patent or two with the drawings, but good luck locating it.

The magneto is a basic permanent magnet alternator or dynamo. There should be a lot of drawings for those - lots of folks wanting to build them for small wind or water power plants.

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Had this cat that insisted on climbing through the window. It was a "city cat" and the owner had just left the window open. When I acquired the cat (owner went to work at the CIA) the windows were screened and there was no way . . .

A spark coil with a couple of wires nailed to the sills cured that cat

- she needed two lessons - to break a lifetime habit.

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With a two pole horseshoe magnet that covers (maybe) 120 degrees of rotation . . . There's a big bare spot with no generation. That and less than optimal pole pieces or armature.

Wave was sort of like a hemisphere with a spike (like a sine wave) superimposed on the first part of the waveform. But that may be unique to my magneto.

If your goal is to raise worms . chances are the waveform isn't all that critical. Ring phone bells - ditto.

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It sure seems like it would make more sense to spin one of those ultra-strong new magnets between some kind of stator windings.

Thanks! Rich

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Doubtless the military has some fancy stuff.

There was a "survival" radio advertised that was pretty neat. The power was stored in a large spring one wound up. The spring powered a dynamo and was regulated so that if more power was needed the spring unwound faster - if the music, for instance, had a lot of bass the spring would spin the dynamo faster.

Stepper motors make good slow speed, low current, alternators. Good for lighting leds as a demonstration.

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I figure peddling my bicycle I probably generate ~100 watts average and can keep that for an hour or two with no problem. I think it would take a lot of work to turn a hand crank at that level long enough to charge a car battery. Say 9-10 amps into a 60-70 amp hour battery?

Leg power maybe, but I'd think solar cells or small gas generator first.

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I doubt that you would be able to crank one enough to turn over a car engine. Have you ever hand cranked an ice cream churn? Think about how little electricity it takes to run an electric one. Multiply that times the additional energy needed to to turn over a modern high compression engine over the efficiency of the charging process.

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Some related sites with pedal power outputs

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When I was a trainee tech back in the late 50's I remember the instructor telling us that the ac waveform output from the magneto generator was deliberately designed to be "peaky" by virtue of the H shaped armature so that it was better able to overcome the initial inertia of the side-stable polarised magneto bell.

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I took a hard disk drive apart and removed the platters. I connected a red LED the leads of the heads that go to the voice coil. When I wiggled the voice coil back and forth in that strong magnetic field, it lit the LED, easily. Also, some of the HDD motors are permanent magnet and when spun will light the LED.

perform

Forget it. Your arm muscles would give out after a few minutes. 14 volts output at an amp is 14 watts, figuting 70 percen efficiency, 20 watts imput to the gen. You can't do that for long; a bicyclist can't put out a sustained hundred watts using his legs, only for a short burst. The thigh muscles are the largest and most powerful muscles in your body.

At 1 amp, it'll take you an awful long time to charge a car battery.

The part of the motor armature that's between the magnets and the media is soft iron and "shorts out" the magnetic field. Kinda like the E-core around a relay coil.

Cheers! Rich

I'd like to take exception to this number here. You produce almost 70 watts just sitting there! (albeit, in the form of heat and not real useful.)

When I was in HS physics, the class got around to the F+MA and all that stuff, and did an experiment to determine just how much power a person can generate. There was a 3-floor stairwell at this school, and what the physics class did was get a few boys to volunteer to run up the stairs as fast as they could, and be timed. Then, of course, the boy's mass times the height, with some gravity factor was the work done,divided by the time it took him to ascend 30 ft. (10 M) of stairs gives power, the rate of doing work. These guys were pushing a horsepower. But you were allowed to cheat - use the handrail, vault instead of turn the corner, whatever. I tried it and made about 300 watts, IIRC.

But that's "fight or flight sprint" mode - nobody could keep that up for any extended period of time, obviously. So, maybe 70 watts would be a good comfortable pace on, say, an exercise bicycle.

What somebody needs to invent is a movie of scenery going by, that moves by (on the big-screen projection TV next to the exercycle) at the same speed that you're pedaling. :-)

I also have an invention for a new type of recumbent pedal - but for a generator, you wouldn't need the gearshift. But I see I've gone over, and that's a topic shift...

Thanks! Rich