Author Topic: Cable type?  (Read 1754 times)

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Offline akarta

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Cable type?
« on: February 16, 2016, 11:14:42 am »
Hi, I'm new here in this forum, but not new to electronics ;)
I have a question: What type cable is used in laptop power supply?
The one that is coaxial and caries 19V DC ? I really like these cables
as they are robust and flexible. I have to power my project from 5V 7A supply
which it is located under desk. 4m. cable is needed and it must look good as it is
visible. standard DC cables does not fit in my situation.
If anybody know part number or other info on these cable please point me to
right direction. 

Many thanks
 

Online mariush

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Re: Cable type?
« Reply #1 on: February 16, 2016, 12:59:45 pm »
Ready made cables with barrel connectors on both ends: http://uk.farnell.com/barrel-power-cords  - just cut one of the connectors and you're done.

Here's standalone cable, like coaxial but not coaxial (multicore screened cable) - I've filtered the results to show only ones with ONE wire inside and insulation on the outside like coaxial cables : http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&categoryId=700000006049&sort=P_PRICE&pageSize=25&showResults=true&sf=502,731&pf=113063006

You should be careful though because at 7A you should use a thick cable unless you want a lot of voltage drop on the cable. Take for example an AWG24 like one of the first results in the link above, the datasheet says it has a resistance of 47 ohms per km , so with a 4 meter piece of cable you could end up with a voltage between 3.5v and 4v at the end of your cable.
See http://www.bulkwire.com/wireresistance.asp to play around with different wire types.

The above applies with ready made cables from the first link as well, most are only rated for up to 2-3A as you can see from product descriptions.
 

Offline akarta

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Re: Cable type?
« Reply #2 on: February 16, 2016, 01:57:20 pm »
Thanks for replay. I have calculated that I need 22 AWG cable. This is why I'm looking for this type of cable. Modern laptop supply can deliver 5 - 7 A and are flexible(exemple dell 130w power brick: 19V 7A). I have looked in your links but did not found anything suitable.
I may reduce cable length to 2 meters, but It does not change that I need , wire gauge will be same  just less voltage drop at the end.
 

Online Monkeh

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Re: Cable type?
« Reply #3 on: February 16, 2016, 02:17:02 pm »
Digikey sell this stuff, but the pricing on longer lengths is silly. 30m is more expensive per metre than 1m..
 

Offline akarta

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Re: Cable type?
« Reply #4 on: February 16, 2016, 03:33:53 pm »
After reviewing prices I am considering just buying used power supply and I will cut off cable for my project. Much cheaper then paying $50 for 5m. cable.  It's shame to destroy good power supply, but there is no better alternative. I may connect 2 cables to get needed length.
Thanks for help!
 

Offline DenzilPenberthy

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Re: Cable type?
« Reply #5 on: February 16, 2016, 03:56:19 pm »
It's not coaxial but some bog-standard 1sqmm 2 core flex would do ok, wouldn't it?

https://www.tlc-direct.co.uk/Main_Index/Cable_Index/Flex_White/index.html

51p per metre or treat yourself to a 100m reel for £30 and use it for other stuff as well.

 

Offline dom0

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Re: Cable type?
« Reply #6 on: February 16, 2016, 05:46:25 pm »
Round speaker cable is commonly available and not too expensive. Also mechanically very robust. H03 and H05 mains cable is an option, too.

Edit: I meant round, not coaxial. Although coaxial speaker cables exist, too, but they aren't as common.
« Last Edit: February 16, 2016, 05:47:57 pm by dom0 »
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