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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details.

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Old 7th Jul 2020, 9:01 pm   #41
Ed_Dinning
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Default Re: DIY X-Ray & Auto Jigger transmitter

Hi Sing, try a plasma globe next; quite simple to make and nothing too dangerous in their construction and use

Ed
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Old 7th Jul 2020, 9:43 pm   #42
regenfreak
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Default Re: DIY X-Ray & Auto Jigger transmitter

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Hi Sing, try a plasma globe next; quite simple to make and nothing too dangerous in their construction and use
Ed I have not messed around with high voltage (e.g. 20KV-500KV) for a long time. These days i focus my attention to amplification of micro volts of RF signal and the ever confusing antenna and transmission line theory. I did fancy building a Lord Kevin's water droplet electrostatic generator, Gieger counter and a Wilson cloud chamber...
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Old Yesterday, 6:52 pm   #43
rontech
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When I got interested in radio three years ago, I reproduced Hertz's dipole experiment using the coherer detector in the attached photo below. The glass tube contains silver fillings and it is very sensitive. Mine was a lash-up with two 70cm brass rods with a spark gap transmitter, a matching dipole receiver, HT ceramic cap and a 10KV flyback transformer. I can set off the coherer a dozen meters away or light up a neon bulb at a close distance < 1 meter.

I still have a working 1920 Wimhurst electrostatic machine. It wont have enough juice to produce X-ray for sure. You can create very weak x-ray using 20KV TV flyback transformer with certain type of valve tubes for sure.

Disclaimer: I do not endorse the following reckless behavior below. The x-ray experiment in the video is very dangerous( in Ukrainian) and viewers should not attempt unless they know what they are doing:

https://www.youtube.com/watch?v=hiYkSnm29b8&t=647s

Does your 1920 Wimshurst machine have leyden jars fitted? They may increase the current capacity somewhat. I my electro freak period ( mid teens 1954 1956 ) Lash up leyden jars increased the discharge diameter about tenfold I estimate
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Old Yesterday, 7:46 pm   #44
regenfreak
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Does your 1920 Wimshurst machine have leyden jars fitted? They may increase the current capacity somewhat. I my electro freak period ( mid teens 1954 1956 ) Lash up leyden jars increased the discharge diameter about tenfold I estimate
Yes, it has a pair of original Leyden jars using metal chains as conductors. I wish i can take a photo of it but I boxed it up in my storage locker along side mountain of junks. I purchased it from an antique shop in Convent Garden,London paying 250 back in 1990. The machine was made in the UK. It can produce up to about 5 inches of spark under dry weather condition.

I also have a working motorised, Van daar Graaf generator made by Griffins in the UK. It can produce about 4 foot of spark. I dont understand why I liked high voltage and electrostatic so much, maybe i got the excitement from the sparks. I was fascinated by lightning in my childhood as I witnessed some bad ass lightning storms.
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Old Today, 12:27 am   #45
Techman
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Default Re: DIY X-Ray & Auto Jigger transmitter

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Yes, it has a pair of original Leyden jars using metal chains as conductors.

I also have a working motorised, Van daar Graaf generator made by Griffins in the UK. It can produce about 4 foot of spark.
I have a number of large Leyden jars with my machine - they can be quite dangerous if left around when fully charged! And surely you mean 4 inches of spark and not 4 foot
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Old Today, 9:01 am   #46
rontech
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Yes, it has a pair of original Leyden jars using metal chains as conductors.

I also have a working motorised, Van daar Graaf generator made by Griffins in the UK. It can produce about 4 foot of spark.
I have a number of large Leyden jars with my machine - they can be quite dangerous if left around when fully charged! And surely you mean 4 inches of spark and not 4 foot
On a good day my home built wimshurst would produce 4" of spark. A Van der Graaf generator would greatly increase the voltage.

I also made a Van der Graaf generator with a square sided perspex tower ca 3 ft high with a modified ball cock copper float as the dome. Meccano motor and mechanicals carrying a silk belt ( modern plastics for belt not availabe to me at that date.

Used the wimshurst as the priming source of charge. ( pointed brass pins for collectors on both machines were made from old acoustic gramophone needles )

Problem was leakage all over the place. Run in the dark, cloudy discharges all the way up the corners of the tower. Very long 18" or so feathery sparks from the equatorial seam of the copper float.

The longer sparks could be felt as a very mild tingle about 2 ft away.
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Old Today, 9:02 am   #47
regenfreak
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I have a number of large Leyden jars with my machine - they can be quite dangerous if left around when fully charged! And surely you mean 4 inches of spark and not 4 foot
Would love to see your machine if you manage to dig it out.

You are right. it is 4". My Van der Graaf produces very weak spark. It prefers a "blow dry" with a hair drier after storage.

I used to be a high voltage junkie that now leaves my living quarter like a mad scientist lab. In the photo below, it is my small collection of DIY tesla coils: the big Tesla coil can produces 1.45 m spark. The small ones include a musical DRSST using IGBT and a half bridge solid state tesla coil with mosfets.
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Old Today, 11:25 am   #48
KeithsTV
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Default Re: DIY X-Ray & Auto Jigger transmitter

At school we had a Van der Graff generator. One evening in the after school radio club one of the lab technicians gave us a demonstration. First he showed us the "normal" 4" sparks which impressed us but then he connected a Leyden Jar across the output and moved the balls apart to about a foot. We were told to stand back as he turned the handle for what seemed like an age then suddenly an almighty crack as a spark jumped the 12". That left a lasting impression on us all. Of course that would not have been allowed in the class but he did show us the best way to draw a spark from it with your finger. Point the tip of your finger towards the dome and you'll feel it but if you point one of the joints in your finger at the dome you'll still draw a spark but you won't feel the shock as much. Something to do with the fact that there are more nerves in the tip of your finger that in the joints.

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Old Today, 12:32 pm   #49
AC/HL
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Default Re: DIY X-Ray & Auto Jigger transmitter

I only remember ours being used to impress parents at open evenings.
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Old Today, 12:50 pm   #50
GrimJosef
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Default Re: DIY X-Ray & Auto Jigger transmitter

I once built a Marx generator demonstrator for an open day at the lab. There was a large rotary handle on the front which, via a couple of pairs of chain-driven step-up cogs, turned a Mini Metro alternator. This powered a solid-state HV invertor which delivered +/-10kV to 5 pairs of 220nF capacitors. So the stored energy at full charge was 110J. The bottom spark-gap in the column self-broke at around this point and the Marx 'erected' (yup, that really is the technical term) delivering 100kV out of the top into a 120mm air arc. The bang wasn't loud enough to be harmful, but we did encourage the audience to put their hands over their ears. They went away impressed too.

Cheers,

GJ
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