mystery object !

Nick Mitchener

COMMITTEE
It is an induction coil, It says it gives a spark of 12mm at 4V you put two bits of wire into the top terminals with a gap under 12mm between them and apply 4VDC across the two terminals on the case. The sliding switch thing on the right reverses the polarity of the DC supply. (not generally recommended to use a power supply due to back EMF spikes)

It works by intitially producing a field in the primary that creates a magnetic field in the core and attracts that sprung disc on the end, this in turn breaks the connection and collapses the field so the sprung bit goes back, thereby continuously making and breaking the field. Each time the field changes in this way a current is induced in the secondary whih is what is connected to the top posts.

This is a baby one, they can be huge. They were used as early high voltage supplies for experiments, they were the basis of wireless telegraphy. There was one on the Titanic used to transmit SOS.

CLEAPSS don't like them and I don't think the broadcast licencing people are that keen. Good to show students I would have thought, I have a whole collection of different sizes.
 
When I first arrived here, I was sweeping out bits of junk from under the cupboards in the chemistry prep room and found one of these (an eight volt version) hiding amid the clutter. Dusted down it looks pretty good for the display cabinet, but it is quite large. Slightly different design with the coil hidden under a sheet and the terminals separate from the main body. They were once used as the electron feed for x-rays, along with the uses mentioned above. Very versatile at one time.
 

Nick Mitchener

COMMITTEE
They were supplied with x ray tubes as childrens toys, as well as for illuminating geissler tubes that could be rotated in geissler rotators, either Froment or Wheatstone. (I have a Froment would love a wheatstone)

They were also used in medical equipment as electric shocks were thought to be therapeutic. (still are in mental health or certainly were relatively recently, they treated my aunt with shocks)
 
It is an induction coil, It says it gives a spark of 12mm at 4V you put two bits of wire into the top terminals with a gap under 12mm between them and apply 4VDC across the two terminals on the case. The sliding switch thing on the right reverses the polarity of the DC supply. (not generally recommended to use a power supply due to back EMF spikes)

It works by intitially producing a field in the primary that creates a magnetic field in the core and attracts that sprung disc on the end, this in turn breaks the connection and collapses the field so the sprung bit goes back, thereby continuously making and breaking the field. Each time the field changes in this way a current is induced in the secondary whih is what is connected to the top posts.

This is a baby one, they can be huge. They were used as early high voltage supplies for experiments, they were the basis of wireless telegraphy. There was one on the Titanic used to transmit SOS.

CLEAPSS don't like them and I don't think the broadcast licencing people are that keen. Good to show students I would have thought, I have a whole collection of different sizes.
Thanks Nick, I thought you would know !

It sounds rather fun, I'll have a play some time.
 
It's a thing of beauty! Great for Hertzian demos. Put 0.1uf poly capacitor across the interrupter, reduces eroding the contacts. Google vehicle coil ignition circuit.
 
It is an induction coil, It says it gives a spark of 12mm at 4V you put two bits of wire into the top terminals with a gap under 12mm between them and apply 4VDC across the two terminals on the case. The sliding switch thing on the right reverses the polarity of the DC supply. (not generally recommended to use a power supply due to back EMF spikes)

It works by intitially producing a field in the primary that creates a magnetic field in the core and attracts that sprung disc on the end, this in turn breaks the connection and collapses the field so the sprung bit goes back, thereby continuously making and breaking the field. Each time the field changes in this way a current is induced in the secondary whih is what is connected to the top posts.

This is a baby one, they can be huge. They were used as early high voltage supplies for experiments, they were the basis of wireless telegraphy. There was one on the Titanic used to transmit SOS.

CLEAPSS don't like them and I don't think the broadcast licencing people are that keen. Good to show students I would have thought, I have a whole collection of different sizes.
A school I was at
Coincidence! I've been requested to demo Hertz's radio wave experiment Tuesday.
It is an induction coil, It says it gives a spark of 12mm at 4V you put two bits of wire into the top terminals with a gap under 12mm between them and apply 4VDC across the two terminals on the case. The sliding switch thing on the right reverses the polarity of the DC supply. (not generally recommended to use a power supply due to back EMF spikes)

It works by intitially producing a field in the primary that creates a magnetic field in the core and attracts that sprung disc on the end, this in turn breaks the connection and collapses the field so the sprung bit goes back, thereby continuously making and breaking the field. Each time the field changes in this way a current is induced in the secondary whih is what is connected to the top posts.

This is a baby one, they can be huge. They were used as early high voltage supplies for experiments, they were the basis of wireless telegraphy. There was one on the Titanic used to transmit SOS.

CLEAPSS don't like them and I don't think the broadcast licencing people are that keen. Good to show students I would have thought, I have a whole collection of different sizes.
I have a huge one of these, thrown out from Longdean. On a 12v battery it throws 8 inch ribbons of sparks between the terminals. Its known in the family as the lightning machine. It must be absolutely lethal and I guess about half a million volts???. One of my best bits of old kit!
 
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