Where get short length of fine enamelled wire in UK?

Where can I get a small spool of fne enamalled copper wire? I'm in the UK and want about 25metres of single strand of enamelled wire.

Most big dealers sell no less than 250g/8 oz but that's way too long for me! These are the sort of diameters.

SWG 40 (.0048) = 36or37 AWG SWG 38 (.0060) = 34or34 AWG SWG 36 (.0076) = 32or33 AWG big thick

The wire is for a body-worn covert mic and the wire will be twisted into a par.

A light-brown low-gloss outer would be ideal for camouflaging the wire but I suspect it doesn't exist. :-(

Reply to
Karen
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Karen wrote in news:Xns9BC99F6C5E8FB451E7A@news-

3.octanews.net:

eBay might work. I've found it good for small and unusual finds. Better, for this, might be salvaged relays, solenoids and small AC or DC motors, tape head demagnetisers... any kind of electromagnet coil. Colours vary more than you'll likely find in commercial outlets. I've even seen dark blue, but never seen it on sale. Salvage is good though, you'll find a wide range of colours similar to human hair colours, some too bright but some near ideal. And free, and in useful amounts. A small hacksaw, a screwdriver, and a pair of pliers, might be all the tools you need to get at them. Getting a look at them is even easier.

Reply to
Lostgallifreyan

On Tue 10Mar 05:40, Lostgallifreyan wrote

I'm not really happy about eBay. Salvage might be good but I worry that I am getting wire with resistence from some transformer.

Reply to
Karen

On Wed 11Mar 02:35, Ross Herbert wrote

Twisting a pair of SWG 40 wires is not so hard at all. Try it. They are only a metre long.

You can stick the twisted pair to a garment or to skin every 6 to 8 inches. You can even us a small stitch on a garment of about 3mm (each wire done separately in a needle). Trouble is the small 3mm visible section sparkles too much and would be noticed.

If it the wires break when they're removed then that's no big deal because they can be replaced.

My thinking is that it's a good thing if the pair break relatively easily. You might get challenged with a question if "that" is a mic, and in response you could then pull it away, breaking the wires and display it is unattached. It's not foolproof but might be better than having no reply.

Anyway, I'm looking for a source that doesn't sell me over a mile of the stuff in a 250 grams reel.

Reply to
Karen

Hi Karen,

I'm sure I can help if you care to contact me directly by e-mail.

- Dave

In article , Karen writes

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Reply to
David Chapman

:Where can I get a small spool of fne enamalled copper wire? I'm in :the UK and want about 25metres of single strand of enamelled wire. : :Most big dealers sell no less than 250g/8 oz but that's way too long :for me! These are the sort of diameters. : :SWG 40 (.0048) = 36or37 AWG :SWG 38 (.0060) = 34or34 AWG :SWG 36 (.0076) = 32or33 AWG big thick : :The wire is for a body-worn covert mic and the wire will be twisted :into a par. : :A light-brown low-gloss outer would be ideal for camouflaging the wire :but I suspect it doesn't exist. :-(

So how do you twist 0.0048" wires into a pair without breaking it? Even when you do manage it, how do you stop the twisted pair from breaking due to snagging on clothing while being worn?

Reply to
Ross Herbert

How much does a 250 gram reel cost?

Last time I looked for wire, all the different sizes and colors were sold in the same size spools with the same weight. So for tiny wire, you are going to get a lot of it if you measure length rather than weight. I doubt if any of the normal wire sources will have anything smaller.

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Reply to
Hal Murray

Karen wrote in news:Xns9BCA9D0E245ED451E7A@204.153.245.22:

It's copper. :) How much resistance can there be? it will be fine. Whatever source of copper wire you use, there will be some resistance, but not enough to be a problem. More important is to use a balanced line input, i.e. a differential amplifier, so noise picked up on the twisted pair will cancel, leaving the sound signal you want intact.

Reply to
Lostgallifreyan

Karen wrote in news:Xns9BCA9FF4EC305451E7A@204.153.245.20:

once you have made the twisted pair, try getting some matt varnish in a small brush and running the wire through the bristles. Once it dries it will be less shiny, especially if you draw it through a gently folded cloth while it's still tacky, ideally the same cloth you'll be using, so any fibres that stick to it will help camouflage it.

Reply to
Lostgallifreyan

Lostgallifreyan wrote in news:Xns9BCB9E5CB7923zoodlewurdle@216.196.109.145:

While you're at it, twist it with a thin strong thread to give it strength and further help with camouflage and varnish retention.

Reply to
Lostgallifreyan

On Wed 11Mar 15:30, Lostgallifreyan wrote

What I meant was that a transformer may have an impedance of 50K and I don't want that wire because I assume the wire is made in a way to give extra resistence.

Good point about the two wires needing to be balanced. I remembered a discussion which started by saying the twisted pair would have to be balanced then someone else said try it without. I'll see what happens!

My recorder has unbalanced inputs and I would rather not get some device to put between amp & mic.

Reply to
Karen

On Wed 11Mar 15:34, Lostgallifreyan wrote

Oh! That is creative.

Not sure how easy it will be to leave a suitable film of varnish or if the varnish can be flexed when dry but it has to be worth a try. I wonder if soft-hold hair lacquer is another way to do this.

You seem to have a good feel for what I am trying to do. Have you got experience of covert recording? :)

Reply to
Karen

You are confusing impedance with resistance. The DC resistance of that 50k winding is much lower.

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Reply to
Michael A. Terrell

Karen wrote in news:Xns9BCBE4A4B3268451E7A@news-

3.octanews.net:

It's ok, they just wind enough windings on them to get those ratings, bearing in mind the characteristics of the core as well. The only reason to avoid transformers is they're sods to unwind. Solenoids, demagnetisers, relay coils, are all neat bobbins you can unreel wire off as easily as if you'd bought it ready wrapped, so long as you cut the bobbin free of any containment without damage.

Re balanced, try it WITH first. :) It's just as easy to build a differential amp from op-amps as a single input type, you just configure the resistors differently, and they're all standard circuits. Unless your wires to the mic are less than about an inch long, you really need that noise cancellation that a diff amp gives.

Despite your recorder having only unbalanced inputs, you might get away with it so long as you don't refer to any ground, only to the chassis or local ground inside it. If you use an electret mic (smaller than dynamic) the FET in it will put out a voltage high enough to help with signal to noise ratio even over an unshielded twisted pair. It won't be hi-fi but it will be useable. You can remove constant noise later with a digital editor too (the kind that take a noise print, so if you use one, record some noise on its own as sample).

Reply to
Lostgallifreyan

Karen wrote in news:Xns9BCBE4AABFBD9451E7A@news-

3.octanews.net:

Nope, but it's an interesting problem. Polyurethane varnish should be ok, it stays flexible for months.. Soft hold hair laquer I don't know about, but it does make me think of the smells of such things as opposed to those of varnishes. It's worth experimenting with stuff that smells like it will be far less out of place than a woodworking varnish kind of smell, if it's to stay un-noticed and be used soon after preparation. Irrelevent, maybe, unless you're going to be in a small unventilated room.

Reply to
Lostgallifreyan

My offer to help is STILL available if you care to contact me directly. I have some very thin TWO-core enamelled wire that will do the job perfectly for you.

- Dave

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Reply to
David Chapman

Hi Dave, sorry I didn't get back to you before. I wasn't sure you were really serious about letting me have some wire.

Email sent.

K
Reply to
Karen

Hello Lostgallifreyan, your post contains a lot of info and much of it intrigues me. Can I break into parts.

You say "it's just as easy to build a differential amp from op-amps as a single input type, you just configure the resistors differently". The mic capsule will be an electret and I was going experiment with (a) an electret mic with two contacts and (b) an electret mic with three contacts.

I was just going to put the mic capsule in place and run the two twisted fine wires to the input of the recorder. In the case of the three wire capsule I would add a resistor between 2 leads (as advised by the manufacturer) to convert it to two wire operation.

I wasn't going to build any amplifier! This is a little bit out of my depth. I was just going to plug the mic. However, now that you have mentioned amps can you point me in the direction of a circuit or web page which might show more detail of the sort of thing you mean.

I would like to avoid removing noise because when I have tried that using an audio editor using a noise sample from a non-speaking part of the recording, I found the speech quality suffered a bit too much.

As background, one particular three wire capsule I have in mind is the micro-sized Knowles FG.

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(I am in the UK.)

This FG-23329-P07 capsule is prewired with 3-wires (positive, negative, output, and also a shield wire from the case. It is in the chart on page 9 of Knowles's Design Guide:

Thank you or anyone else for any info.

K
Reply to
Karen

Karen wrote in news: snipped-for-privacy@text.news.virginmedia.com:

I tried Googling for advantages to be had from 3-terminal electrets, and it could take hours or days to find out that way, so it might be best to just go with a 2-terminal scheme by modifying as you describe if needed, for a 3- terminal capsule. If there WAS any significant advantage to 3 terminals, it would be a lot easier to find examples than it is now. I couldn't find one at all that wasn't explaining how to convert to two.

You will need to provide power to the mic capsule somehow, so either modifying the internal circuit in the recorder, or adding something outside it. Most times, the second choice is better, unless you really want a permanent mod to the recorder.

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shows a small kit, which might be the best way to go. That way most of the work is done, but modification is easy, and you can devise your own housing, for best discretion.

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is a good page for info, and likely a way to buy a built circuit. They're very small.

For circuits for building yourself,

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or
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have some ideas.

Takes practise.. :) Ideally, use a small analysis window size, and reduce by no more than 24 dB unless the noise is VERY constant and smooth, in which case try for up to 35 dB reduction. As an example, if you get the Sonic Foundry version 2 noise reduction plugin, set for mode 3 (of 0~3), and tweak the noise bias in conjunction with the reduction control, it should be easy to get very clean results. After NR you can apply an 'Aural Exciter' or smilar tool (Hyperprism do one, as do Aphex) to build on the HF part of the signal. This is seriously cool, well worth doing, it increases intelligibility enormously. (I used it on recordings from FM as well as sounds used in music making).

Some neat mics shown in that PDF! Not sure which is best, but I remember reading about a Lavalier mic system using a tiny Panasonic capsule and a simple preamp. Lavalier is a good key to searching because it implies a long wire between a tiny capsule and the main amp. Most use a sheilded cable but twisted pairs do get mentioned.

I think the thing to do is try one of the simpler ideas I liked to, as the mics aren't balanced, so you can just use a low noise op-amp IC. If you get too much noise, consider some of the more elaborate ones, especially those that use a small inductor on the preamp input.

Reply to
Lostgallifreyan

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