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Topic: exposing the internal core metal of a protected tiny wire without damaging it ? (Read 2127 times) previous topic - next topic

fourchette

hi there,

following my post http://arduino.cc/forum/index.php/topic,73169.0.html

instead of trying to find the right connectors or solder stuff on the board, i was thinking maybe i could go mac gyver style

i already know the application protocol used between host and device.
i know the device uses either usb or serial communication (on second thought, i'd say usb, but i am not sure)
i know the communication is half duplex (meaning it's a question->answer approach so to speak, not both ends are not talking to each other at the same time)


it looks like there are 4 wires here. my guess is
* black is ground
* red is power
* green and white may be signal+ and signal- ???

==> if this hypothesis is correct, then i care only about green and white wires.

maybe if i cant identify the connectors and am too affraid to solder stuff on the main board, i could try to strip a very small part of both green and white wires and attach a probe there like


http://radiospares-fr.rs-online.com/web/p/grippe-fils/1030254/

and from there connect those two probes to either bus pirate or an arduino board and continue tinkering/exploring

my questions
* does such an approach make sense ? or is it plain stupid ?
* how to strip such tiny wires without damaging the cable?
    - does burning the plastic cover on about 1mm of wire would work? or is leaving burnt plastic on the wire likely to introduce noise and/or connection issues ? is heat likely to cut the metal too ? (i was thinking of using a soldering iron, but what temperature should i use then? alternatively i was thinking of such anti-wind lighter flame such as (but it probably is a too big flame to make a decent job (would probably burn the rest too, no?)
    - should i try to strip them with a surgeon scalpel ? if so, how likely is it to cut the wire too ? (not to mention hurting myself :p) ? is there a particular technique to do it right ?
    - any other idea to partially expose the core metal of the tiny wires without damaging the overall cable ?
   
thanks for the ideas :)

fourchette

cr0sh

Can you poke a really fine needle through the insulation and into the wire (it looks stranded, on your other post) - then attach the clips to the needles? Not the greatest for a connection, but maybe it is a possibility. Another way might (?) be to "roll" the wire under a razor/scapel, to cut the insulation (but not the wire), then use a couple of tweezer to pull the insulation back from the cut, exposing a bit of wire (I'd try this after the needle, and cut at or near the needle hole)...
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

justjed

There are such things as thermal wire strippers. So careful application of heat isn't out of the question.
... it is poor civic hygiene to install technologies that could someday
facilitate a police state. -- Bruce Schneier

fourchette

great !
i tried with very small needle but i couldn't get the needle to "drill" (get through) the wire. i'm affraid of cutting it. prior to use a razor / scapel, i might try the heat with a soldering iron

would you guess the temperature i should use to melt the plastic without cutting the core metal ?

also, i was thinking of something else


last year i had some trooble with internet at home. it turns out to be a problem with some connectors on the wire right outside my home

instead of fixing the broken connectors, the guy used some scotchlock little connectors

something like

however, he had to cut the wires first :(

i was thinking maybe Scotch produces a similar scotch lock mecanism that
1) prevents from actually cutting the wire you want to connect to
2) applies to very small electronic wires (not electric or telecom wires)

maybe something like

(check out the one with the yellow wires, it'd be exactly the thing ==> plugging a parasite wire to an existing wire without cutting the existing wire)

has anyone tried something like that ?

thanks

FeersumEndjinn

I've used the Scotchlock style before, but you have to be aware that you will easily need 12 - 15mm of play to use these as they require the wires to come into the device in parallel rather than end-to-end.

Grumpy_Mike

Quote
if this hypothesis is correct, then i care only about green and white wires.

No you care about the ground as well to give you a reference for your measurement.

If the wire is PTFE coated then you are not going to melt it with a soldering iron.

Quote
would you guess the temperature i should use to melt the plastic without cutting the core metal

I would doubt you would melt the core metal. However don't even think of using a flame of any sort, they are too uncontrollable.

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