22 DCC wire?

[pagan 1962AS]

I hope that some one can shed some light on to this question. I have decided to build a variometer style xtal radio and I have down loaded a 1925 mag article from the internet.

It states that when winding the coils a no 22 DCC wire should be used. I have never heard of DCC wire. Will ordinary insulated copper wire suffice and if yes what gauge?

Thanks.

[Station X]

DCC denotes double cotton covered wire. As far as I know it's unobtainable these days.

Enamelled copper wire can be used instead. Depending on the origin of the mag article, this should be 22 SWG (Standard Wire Gauge) or 22 AWG (American Wire Gauge). However wire these days is generally sold by diameter in mm rather than by gauge. Just google SWG and you'll find a conversion table.

You can buy suitable wire here:-

http://www.scientificwire.com/index.html

Other suppliers are available.

[Mr Moose]

Hello,


DCC wire is still available here http://www.wires.co.uk/acatalog/dcc_wire.html but is quite expensive.
22swg is 0.71mm which they show at £2.65 + VAT for 5 metres.

You could use enamelled wire instead and the exact size of wire is not critical provided it is somewhere near.

Yours, Richard

Enamelled wire is stocked by Maplin, less than a tenner for 250g which is enough for lots of coils.

[kalee20]

Yes, DCC is available but expensive.

Covering with cotton, rayon, silk etc is useful if either it is multistranded, or if the coil it's being used for is wave wound. Enamelled wire is just too smooth to stay in position as it is laid obliquely across the bobbin.

[pagan 1962AS]

Thanks for the info, I thought the gauge would be similar, anyone know as to what DCC actually stands for?

I have ordered a roll of 22 SWG from ESR at only £1.97 for 50g (approx 14 m in length).

www.esr.co.uk

lots of other stuff there too.

[Station X]

Thanks for the info, I thought the gauge would be similar, anyone know as to what DCC actually stands for?

Looks like I'm wasting my time here. Take a look at post #2.

[pagan 1962AS]

Yes, sorry about that I skim read the reply at work yesterday and I was in a rush while the boss was out. Whoops!

[emeritus]

I believe that DCC copper wire was used in the hat trade before people started experimenting with electricity, and was the only insulated wire available to early experimenters. It was the only sort of insulated wire used in the physics lab at my school in the 1960's for electricity experiments: I think someone must have acquired several large spools of the stuff. I still have a small spool of my father's somewhere in the garage. I haven't used any for years.

As I recall it was a pain to strip back the insulation as the two layers are wound with opposite hands of twist: burning off with a Bunsen Burner was quite effective! Once stripped, it tended to unravel further unless you put some glue or varnish on the end.

[pmmunro]

Emeritus,

Thanks for posting the information about the original use for double cotton covered wire; it's the sort of thing I find interesting and I hope I'm not alone in this. Is there a source of this information you could refer me to please?

PMM

[Radio Wrangler]

The world is going full circle, the Scientific Wire Company in London seem to be doing a lot more business in jewellery wires than in electronic. When buying silver plated wire for RF work, be sure you don't get the jewellery grade. Hats to radio to jewellery!

David

[emeritus]

In the 1970's and 1980's, looking through technical journals was part of my job, and I think it was Edison who used cotton-covered wire from the hat industry in the early days. After all this time I can't recall the source, and I drew a blank on this on a web search. It could be in an American book that is in store at my mother's, or I could have misremembered!

What I did find, and which seems to be relevant to the problem posed by this thread, is an article from a 1953 Shortwave journal that discusses the problems that can arise when substituting one type of wire for another in RF coils, and hints for practical solutions: DCC wire is mentioned. Free PDF download at http://www.bunkerofdoom.com/lit/gehn...VOL08_NR05.PDF


As far as the UK is concerned, a description of the origins of cotton-covered wires is given in a Science Museum booklet, published in 1972, that I bought many years ago: "Electric Cables In Victorian Times" by R. M. Black, SBN 11 290123 9. It is years since I last looked at it, and I find that it doesn't explicitly describe or illustrate the construction of the insulation layers. It mentions "cotton covered" and "cotton braided" types, and that machines for applying cotton coverings to iron wires intended for making crinolines were adapted for covering copper wire for electrical purposes. No doubt this machinery allowed the mass production of insulated wire.

The relevant passage is in pages 13 and 14, in the chapter titled "Insulated Telegraph Cables".

Cotton and Silk Insulation

One of the earliest manufacturers of insulated wires was William Henley (1814 to 1882) who set up a small workshop in London in 1837 to manufacture silk and cotton covered wire, and to design and construct experimental electrical apparatus. Henley soon came to the attention of Professors Daniell and Wheatstone at Kings College, London, and this was to involve him in telegraphy and, later, in submarine telegraphy. In 1859 he moved to larger premises on the Thames at North Woolwich, and by 1873 his works covered an area of over 16 acres and included a wharf for the loading of submarine telegraph cable into his own three cable laying ships. W. T. Henley's Telegraph Works Company was formed in 1880, with Henley as the Managing director.

Another manufacturer who started with the application of cotton braids and coverings to wire was Walter Glover (1846 to 1893), who established a small engineering works in Salford in 1868. Glover, then aged 22, covered a wide field of engineering activities which centred around the manufacture of machinery for the then blooming Lancashire cotton industry. During his travels about the country in connection with these activities he became acquainted with George James, a Nottingham engineer associated with the lace industry and a patentee of a series of machines devised for the manufacture of cotton braids and cords. Around 1875 these machines had been adapted to apply a cotton braid over iron wires, the braided wire being used for the support of ladies' crinolines. With the growing demand for insulated wires and cables occasioned by the onset of the electric lighting era, and the general increase in the requirements for telegraphy and signalling cables, Glover realised that James's machines could, with minor alterations, be used for the application of insulation to wire conductors. With James a partner, Glover established the Salford Electrical Wire Works. At first some twenty men were employed on the manufacture of various types of cotton covered and cotton braided wires for use on bell, signalling, telephone and other simple electrical circuits. With the growth in demand for insulated conductors the original machines were improved and a number of patents secured which kept pace with the new techniques. This resulted not only in a demand for insulated wires and cables, but also for cable making machinery, and a considerable business was built up necessitating the opening of a second factory in 1880.

[pmmunro]

Many thanks Emeritus. There's some useful information to follow up there.

PMM.

[greenstar]

This may be of interest.(Radio Digest, 1924). I'd like to know if it is the case that DCC wire would be a better choice for tuning coils. I would guess that selectivity is achieved more through developments in circuitry in the last few decades, whereas in the early 20's with only a few components, their performance was vital.

Tony

[turretslug]

Originally Posted by Radio Wrangler

When buying silver plated wire for RF work, be sure you don't get the jewellery grade.

I've heard it said that "tiger tails" (stranded fine stainless steel jewellery wire) can be used as a replacement for the steel drive cord used in some Eddystone receivers and the GEC BRT400. I don't suppose it makes for an easy job, though! It's very inexpensive and crimp ends are also available, as I don't suppose that the thinly plastic-cored stainless steel is easy to solder.

Colin.

[jackplug]

Interesting comments, I would expect DCC to increase the wire spacing when winding a coil and hence the inter turn capacity. This will ultimately effect the Q? Any comments on that?
Dave