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Vintage Resistance Box

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Vintage Resistance Box

Post by Sparks » Sun Jun 05, 2016 5:50 pm

Found this on a car boot sale last week. Perefct working order!
Vintage Direct Reading Resistance Box
Evershed & Vignoles, London
I believe that it dates back to the mid 1920s, or early 1930s.
Bob
Attachments
Resistance box open (Large).JPG
Resistance Box

 
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Re: Vintage Resistance Box

Post by FIXITNOW2003 » Mon Jun 06, 2016 8:24 am

Nice find

 
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Re: Vintage Resistance Box

Post by crackle » Tue Jun 07, 2016 6:43 am

That is a coincidence, I bought one from a bootsale on Sunday as well.
It appears to be designed to be part of a Wheatstone bridge circuit.
It is nicely made and all works pretty well but seems to have a permanent 20 ohm minimum resistance, I have not found out why yet.
Has anyone got any information on this make and model, age, its use, or why it has a 20 ohm bias. ?

I bought it as I was interested to see what was in them and how they were made, not sure what I will do with it, I will probably sell it on.
Mike
Attachments
resistance box.jpg
resistance box2.jpg

 
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Re: Vintage Resistance Box

Post by CTV » Tue Jun 07, 2016 7:56 am

Present company I'm sure know how these resistance decade boxes can be of great use. For the benefit of those that don't, these are superb for hooking in circuit when trying to figure out an unknown resistance a circuit requires.

For example, when replacing a selenium rectifier with a silicon the series limiting resistor can be easily calculated by dialling in a resistance until the desired H.T. is reached. Aidan might find yours ( Crackle) useful if you do decide to move it on as he's about to replace such a rectifier and will need to calculate the series resistance required. Saves a lot of time tacking in and out resistors until you get it right.

I've often thought about getting one but more modern than these, just never got around to it.

 
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Re: Vintage Resistance Box

Post by Kalee20 » Tue Jun 07, 2016 8:50 am

I used a sub-standard ammeter of Evershed and Vignoles manufacture in the 1980's, very good well-made instrument. Don't know much about the company, apart from that this meter looked of late 1950's or early 1960's build... and I have a vague recollection of hearing that they were bought out by Tinsley.


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