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wiring question for scope? Solid/Stranded/Gauge

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#1 SACK

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Posted 12 March 2013 - 10:22 AM

Howdy,
For you electrical guru's,I am getting ready to wire up a scope.
On this scope there will be 3 fans, servo cat jr, sky commander powered by 12volt, and secondary mirror heater.
Any advantage to solid over stranded, where there is no movement or flexing needed?
What gauge, I am considering 16gauge or 18gauge for this application. Thanks for sharing!!
Jonathan

#2 stmguy

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Posted 12 March 2013 - 11:36 AM

I'd use stranded as it is more flexible , have to know the current draw for the gauge

Norm

#3 polaraligned

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Posted 12 March 2013 - 01:06 PM

If there is no flexure, solid is fine. The phone company overhead wires are solid and withstand decades of wind, etc. 16 ga sounds a bit heavy. Sky commander is just a DSC? The 18 ga should be more than enough.

#4 SACK

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Posted 12 March 2013 - 10:02 PM

It will be drawing 1.5 to 2 amps max.
Thanks you.

#5 polaraligned

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Posted 14 March 2013 - 12:43 PM

Go with the 18 ga. Plenty.
Your concern as the wire gets thinner is the voltage drop. It will act like a resistor between your battery and device. You will be happy with the 18 ga.



#6 Achernar

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Posted 14 March 2013 - 05:52 PM

If you are making cables with those RCA connectors, use stranded wire. Solid wire used where connections can experience flexing will fatigue and break. That is why stranded wire and cable only is used to hook up electric motors. Also, if you are making heater strips, don't solder the heater strip to the lead, use butt splices that are crimped on, and cover each conductor with heatshrink tubing, then cover both with another layer of heat shrink. Connections of solid to stranded wire tend to break also. Strip enough of the stranded wire to solder the resistors in a ladder configuration to make your heater strip.

Taras

#7 Startraffic

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Posted 18 March 2013 - 07:36 AM

polaraligned,
Telephone wires don't get that much flex in them & they still break, that's what you see with those overhead splice enclosures.

Jonathan,
Stranded wire if there is any flex in your cabling. More smaller wires allows for more flex without breakage and still be able to carry your current draw.

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#8 bremms

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Posted 18 March 2013 - 07:47 AM

Stranded wiring. The finer the better. There are usually two different strandings. I like the silver plated Teflon coated stuff, but is sucks if you have to buy a bunch. Nobody really uses solid for hook up wire. In fact, it isnot recommended for any application like a fan.

#9 obin robinson

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Posted 18 March 2013 - 08:23 AM

Where in Texas are you? I have A LOT of aircraft-grade wire which I use for any and every electrical project. It is light, unbelievably durable, and highly conductive. Just let me know how much you need and pay for the postage (which should be dirt cheap for a few feet of wire).

obin :cool:

#10 don clement

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Posted 18 March 2013 - 11:45 AM

It depends on how much voltage drop you can tolerate for given current requirement. Considering only steady state conditions (no switching transients e.g. starting motors, switching electromechanical relays, high speed switching circuits like PWM controllers) the IR voltage drop will be current draw times the resistance of the wire. The wire resistance will be rho times wire length divided by area of wire cross-section, where rho is the resistivity of the wire material (typically copper), and the area of the wire cross-section is the wire gage. So the larger the wire gage the lower the resistance. Remember the lower the wire gage number, the larger the wire cross-section. The longer the wires, the more the resistance and the larger the voltage drop.

Also switching transients like starting motors or electromechanical relays can induce voltage spikes in high impedance wires (i.e. small gage, long length wires) which may interfere with sensitive low voltage electronics like CCD cameras. IMO: the larger the wire gage and the shorter the wire length the better. Ferrite beads can help here http://en.wikipedia....ki/Ferrite_bead

I always use stranded wire for connecting wiring as stranded wire resists bending much better than solid. BTW my personal favorite hook up wire is Teflon insulated stranded silver plated copper conductor.

The bottom line is you will have to try out connecting wire size for your application.

Don Clement






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