wire

[kennyk]

I'm tying myself in knots looking at wire on the various suppliers' sites (RS, farnell etc) and truth be told I've no idea where to start in terms of what specification of wire I need to handle the heater current of DHTs.


I don't want to go overboard and get something ridiculously over-specced, but equally I don't want something that's at risk of overheating and catching fire!

is something along the lines of 24/0.2 in the right area? (18-19 AWG, 0.75mm2 ) that I've found on eBay

[Paul Barker]

there will be a plethora of ways people use.

For transformer winding I use:

Diameter (D) = t times square route of I (current in amps).

t is the quality factor. When widning a transformer you have to compromise quality factors if other factors require it, such as window size, decisions lowest frequency of interest against dc resistance etc. You balance these factors, so you may find yourself compromising your t to achieve another criteria.

a t of 0.7 is derived from 2.5 amps per sq mm.
0.8 from 2 amp
0.9 from 1.5 amp

One side note, whichever chart you decide to follow, realise that they are all conservative. But a warning note, they are intended for wires to run separately in free air. When you bundle wires you have to adjust for the combined heat and inability to shed heat.

For audio I have never believed in bundled wire, unless they are all doing the same job like a multicore.

The method of point to point wiring where wires of different purpose only cross and never run together is best, though it looks untidy. The tidy jobs like the Leak Stereo 20 or most OEM wiring bundles have them all coming together and going in a trunk down the centre. Looks absolutely beautiful.
But while you are listening it is hidden from view.

household cable is quoted in circular mills, not diameter. You need to learn Pythagoras or google for a converter. Find out what your chosen cable is specified in then convert it yourself with pi or look up a chart or calculator on the web.

[ed]

Hi Kenny

24/0.2 should be good for 6amps according to maplins product..I check the heater requirements against the spec of the wire...not sure if it's the best way but it sure is simple.

is this any good?

[IslandPink]

I'll use 1 x 0.6mm single core up to about 1A , but above that I'll go to stranded for more core area. I suppose that's slightly above 3A/mm^2 so a bit more than what Paul would use for transformers - but that's probably OK for a short run of wire in air .

[kennyk]

Thanks guys, most useful. I kind of thought that 24/0.2 was about right but just wanted confirmation. I've ended up ordering some 32/0.2 as well.

[Ray P]

I'll use 1 x 0.6mm single core up to about 1A , but above that I'll go to stranded for more core area.

According to HiFi Collective their 1 x 0.6mm single core is rated to 7.5A 500V?

Given my need for small quantities I buy this for most hook up wiring in my projects, plus it's easy to work with and is available in various colours, though I seldom burden it with much current ( I think the heater wiring on a 300B will be the highest).

Ray

[Greg]

Here's a great source for quality wire at nice prices. Won't meet everyone's needs but pretty good if you drill down into the catalogue.

http://wires.co.uk