UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Other Vintage Household Electrical or Electromechanical Items

Notices

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.

Reply
 
Thread Tools
Old 14th Jul 2022, 9:50 am   #1
Wishiknewmore
Hexode
 
Join Date: Oct 2016
Location: Darlington, County Durham, UK.
Posts: 315
Default Old coil switch thing. Identified as a Ruhmkorff induction coil.

Hello all, just bought this because Iím not sure what it is (itís becoming a habit!)

Its base is about 50mm x 125mm, the coil connects to two terminals at the top of the bobbin (one is broken off/missing)

It is not a solid base, it has a removable wooden base (not yet removed)

There is a Ďtrapezoidal?í switch at the bottom (broken and screw missing)
I would have thought that when the coil was energized it would break the connection between the vertical posts, one with spring and one with adjuster, but they are permanently connected.

I was told it was a Morse key, but obviously not

Any ideas?

Many thanks Philip
Attached Thumbnails
Click image for larger version

Name:	IMG_4669.jpg
Views:	232
Size:	54.9 KB
ID:	260879   Click image for larger version

Name:	IMG_4668.jpg
Views:	199
Size:	57.0 KB
ID:	260880   Click image for larger version

Name:	IMG_4666.jpg
Views:	191
Size:	67.0 KB
ID:	260881   Click image for larger version

Name:	IMG_4667.jpg
Views:	165
Size:	141.9 KB
ID:	260882  
Wishiknewmore is offline   Reply With Quote
Old 14th Jul 2022, 10:10 am   #2
Jon_G4MDC
Octode
 
Jon_G4MDC's Avatar
 
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 1,477
Default Re: Old coil switch thing

Looks like an induction coil and interruptor. If the insulation is still good it should produce some good sparks.
Jon_G4MDC is offline   Reply With Quote
Old 14th Jul 2022, 10:11 am   #3
joebog1
Nonode
 
joebog1's Avatar
 
Join Date: Jun 2015
Location: Mareeba, North Queensland, Australia
Posts: 2,209
Default Re: Old coil switch thing

I would say its a morse receiver. It would have "buzzed " on receipt of a signal.
I am probably wrong, but that rings bells in my head.

Joe
joebog1 is online now   Reply With Quote
Old 14th Jul 2022, 10:24 am   #4
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 19,316
Default Re: Old coil switch thing

Definitely not a morse key.

Might be an electric shock coil.
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now   Reply With Quote
Old 14th Jul 2022, 10:38 am   #5
G6ONEDave
Octode
 
G6ONEDave's Avatar
 
Join Date: Dec 2019
Location: Owston Ferry, North Lincolnshire, UK.
Posts: 1,099
Default Re: Old coil switch thing

Looks similar to a Ruhmkorff induction coil as in this link.

https://antiquescientificgadgets.com...on_coil_2.html

Dave
__________________
Quote "All is hyperthetical, until it isn't!" (President Laura Roslin, Battleship Galactica)
G6ONEDave is offline   Reply With Quote
Old 14th Jul 2022, 10:44 am   #6
D.Finney
Pentode
 
Join Date: Nov 2011
Location: Wigan, Greater Manchester, UK.
Posts: 142
Default Re: Old coil switch thing

Looks like an early 20th century medical coil (shock treatment machine).
D.Finney is offline   Reply With Quote
Old 14th Jul 2022, 10:49 am   #7
Hartley118
Octode
 
Hartley118's Avatar
 
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 1,989
Default Re: Old coil switch thing

It's certainly an induction coil and may be an electric 'shocking coil' - once believed to be therapeutic. It looks rather small to be a sparking induction coil, but it's difficult to be sure from the photos. Comprehensive info at https://en.wikipedia.org/wiki/Induction_coil .

I'd be undoing those brass wood screws and whipping off that wooden plate from the base to see what connections lie within.

The coil itself will have a primary winding - probably fairly robust wire, and a secondary of many many turns of fine wire. You'll be very lucky if the secondary is still complete.

The primary circuit is completed through the contact breaker just like a traditional electric bell trembler and is probably designed for a battery from 3V to 6V. I'd first work out which connections go the primary and try wiring it up via the contact breaker (needs cleaning with fine sandpaper). Once you've got it buzzing, see what comes out of the secondary.

Martin
__________________
BVWS Member

Last edited by Hartley118; 14th Jul 2022 at 11:11 am.
Hartley118 is offline   Reply With Quote
Old 14th Jul 2022, 11:44 am   #8
David G4EBT
Dekatron
 
David G4EBT's Avatar
 
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 4,901
Default Re: Old coil switch thing

Yes, definitely a Ruhmkorff induction coil.

I think they may have been used in school science lessons, perhaps in the 1930s.

I went to an inner city secondary school in Nottingham from 1950 - '54.

All of the text books and equipment were pre-war cast-offs from the Grammar School. I recall the science teacher demonstrating a Ruhmkorff induction coil, in part, to to explain how an induction coil is used to create a spark to ignite compressed gases in the 'Otto cycle' of a four stroke internal combustion engine. The underside of the coil was stamped 'Mundella Grammar School', so I guess it dated from the 1930s.

I picked a Ruhmkorff coil up from the NVCF in 2015 for a couple of pounds.

It needs re-wiring and a new base, which I've never got round to making.

It does work, and boy does it tingle if you're minded to hold the output terminals!

Some pics attached, and a diagram showing how - when the trembler vibrates and induces a stream of low voltage pulses in the iron cored primary coil - that in turn induces a much higher spiky voltage in the induction coil, which appears at terminal marked 'G'. (Fully explained in the Wiki article linked in the previous post).

It would have had two metal tubes about 15mm diameter, and 7.5cms long connected by wires to the terminals. A party trick was for several people in a circle to hold hands and the end two to hold the tubes, causing the current to flow through the group. Didn't take long before someone let go!
Attached Thumbnails
Click image for larger version

Name:	Induction Coil end view.jpg
Views:	69
Size:	50.1 KB
ID:	260916   Click image for larger version

Name:	Induction Coil front view.jpg
Views:	69
Size:	65.7 KB
ID:	260917   Click image for larger version

Name:	Induction Coil underside.jpg
Views:	71
Size:	73.2 KB
ID:	260918   Click image for larger version

Name:	Induction Coil Diagram.jpg
Views:	72
Size:	81.3 KB
ID:	260919  
__________________
David.
BVWS Member.
G-QRP Club member 1339.
David G4EBT is offline   Reply With Quote
Old 14th Jul 2022, 12:26 pm   #9
Wishiknewmore
Hexode
 
Join Date: Oct 2016
Location: Darlington, County Durham, UK.
Posts: 315
Default Re: Old coil switch thing

Thank you everyone, Yes it certainly looks like a Ruhmkorff induction coil, so far I have resisted the urge to take the screws out of the bottom as I have too too many things in bits at the moment, But I think it has earned it place for a bit of restoration and a search for a suitable terminal for the one that is missing.
I never cease to be amazed at the knowledge and help on this forum.
I may be coming back for advice on rewinding the coil!
many many thanks again
Philip
Wishiknewmore is offline   Reply With Quote
Old 14th Jul 2022, 12:40 pm   #10
Techman
Dekatron
 
Techman's Avatar
 
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,293
Default Re: Old coil switch thing

Here's my small collection.

Ideally run from a 6 volt accumulator - that's a 6 volt lead acid battery.

Don't try to run one from a modern power supply - the back EMF will likely blow it into next week!
Attached Thumbnails
Click image for larger version

Name:	P1150475.jpg
Views:	89
Size:	104.5 KB
ID:	260920   Click image for larger version

Name:	P1150476.jpg
Views:	66
Size:	98.9 KB
ID:	260921  
Techman is offline   Reply With Quote
Old 14th Jul 2022, 3:53 pm   #11
Techman
Dekatron
 
Techman's Avatar
 
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,293
Default Re: Old coil switch thing

Well I suppose it had to be done.

I've got period accumulators, but I'm not filling them with acid at this point in time, so I got a car battery and a hefty ballast resistor to limit the current and we had high voltage sparks. They were running a bit over voltage and the larger induction coil should really be capable of performing better, but at some point in its life it's been left connected to a supply with its contact breaker in the fully closed position, causing overheating and quite a lot of wax has run out, as can maybe be seen. The smaller coil isn't encased in wax.

Photos below show the spark discharge from both coils, which is continuous. Shown in a darkened room, and also with curtains opened to show the setup.
Attached Thumbnails
Click image for larger version

Name:	P1150477.jpg
Views:	88
Size:	28.5 KB
ID:	260934   Click image for larger version

Name:	P1150478.jpg
Views:	94
Size:	30.0 KB
ID:	260935   Click image for larger version

Name:	P1150479.jpg
Views:	93
Size:	111.1 KB
ID:	260936   Click image for larger version

Name:	P1150481.jpg
Views:	88
Size:	20.9 KB
ID:	260937   Click image for larger version

Name:	P1150484.jpg
Views:	83
Size:	112.8 KB
ID:	260938  

Techman is offline   Reply With Quote
Old 14th Jul 2022, 5:11 pm   #12
Wishiknewmore
Hexode
 
Join Date: Oct 2016
Location: Darlington, County Durham, UK.
Posts: 315
Default Re: Old coil switch thing

That seems like fun, certainly on the to-do list!
Wishiknewmore is offline   Reply With Quote
Old 14th Jul 2022, 7:23 pm   #13
Techman
Dekatron
 
Techman's Avatar
 
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,293
Default Re: Old coil switch thing. Identified as a Ruhmkorff induction coil.

Yes, it's certainly fun - filled the room with ozone yet again!

I'll expect yours to be up and running, producing a stream of sparks with pictures to prove by this time next week at the very latest - no excuses!

The same with David's example. It just needs a bit of fettling (like these things always do) to get it sparking - just so long as the secondary winding is still in tact. I can't remember if I've ever removed the base from either of my examples, but David's example should be fine with that original wiring - it's all spaced out enough not to short out. It looks like it's lined with hardboard, unless it's made of hardboard with a wood veneer on the outside.

It's years since I've 'played' with mine in anger, and I thought that the gap that the spark could jump on the larger coil was bigger, but having looked at the spec. it seems like it's performing near enough correctly, with it being not far off the quoted 30 mm.

They were still being made in that style in the early 60s.
Attached Thumbnails
Click image for larger version

Name:	P1150485.jpg
Views:	56
Size:	66.1 KB
ID:	260954  
Techman is offline   Reply With Quote
Old 14th Jul 2022, 8:08 pm   #14
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 7,478
Default Re: Old coil switch thing. Identified as a Ruhmkorff induction coil.

Hi Philip, make sure you dry it out well before attempting to operate it.
It looks a lot like some of the home made units described in some of my Model Engineer booklets from 1910

Ed
Ed_Dinning is offline   Reply With Quote
Old 5th Aug 2022, 2:41 pm   #15
avocollector
Heptode
 
Join Date: Jul 2010
Location: Wellington, New Zealand.
Posts: 619
Default Re: Old coil switch thing. Identified as a Ruhmkorff induction coil.

One thought/note of caution. In my 1890's 'Boys Modern playmate' book which has instructions on how to build one of these coils (and how to make the Potassium Bichromate cells to run them), the suggestion is to use the hollow rectangular base to hold 40 sheets of tin foil (inerleaved at alternate ends), interspersed with oiled paper 'to form a simple capacitor which will 'greatly improve the performance'. How good such an item would be after 100+ years is a moot point BUT you might just get a hefty belt off it if you've run the coil.
avocollector is offline   Reply With Quote
Old 5th Aug 2022, 3:28 pm   #16
G6Tanuki
Dekatron
 
G6Tanuki's Avatar
 
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 11,358
Default Re: Old coil switch thing. Identified as a Ruhmkorff induction coil.

Attach a few tens of feet of wire to the output and you will easily wipe out the neighbours digital TV reception...
__________________
"The future's so bright I gotta wear shades". --Timbuk3
G6Tanuki is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 3:26 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.