| Electronics > Beginners |
| Estimate length of a large spool of cabling |
| (1/3) > >> |
| groinksan:
I have an interesting exercise, and I'm hoping some of you may have an idea how to do this.... I have two large spools of cabling. I'm trying to figure out the amount of cable left on each spool. Spool #1 is "4-1/C THRN/THWN 600V STR (19 STR) 90C White (T90) BUILDING WIRE UL83" I have access to both ends of the wire on the spool. Spool #2 is "CABLE, 24 AWG, 25 PAIR, UNSHIELDED TWISTED PAIR COMMUNICATIONS RISER CABLE SOLID BARE COPPER CONDUCTOR CAT 3" Unfortunately I only have access to one end of the wire - the other end is buried deep in the spool. The sleeve does show foot markers, but I have no means of digging into the spool itself and finding the other end unless I actually unravel the entire spool. And I'm not about to do that! I have a DC power supply that can control the voltage and current, and a multimeter. At least for spool #1, I was thinking about using Ohm's law and power rule to give me an estimate of the length of cable on the spool. Maybe send some current through one foot of the wire, measure, send current through the entire spool, and then make some estimations from that. But with spool #2, I wouldn't even be able to do that since I can't access the other end of the pairs. Any ideas how I can estimate the total length of both spools? |
| tautech:
TDR using a fast scope. |
| nugglix:
--- Quote from: tautech on November 03, 2018, 06:18:57 am ---TDR using a fast scope. --- End quote --- As shown here: |
| kripton2035:
use some cheap device like this one to measure cable length https://www.ebay.com/itm/Portable-5E-6E-RJ45-RJ11-Network-LAN-Length-Cable-Tester-LCD-Display-Meter-BI801/142987857674 |
| groinksan:
Would this circuit do the trick? https://www.ebay.com/itm/TDR-Time-Domain-Reflectometer-Fast-Clock-Version-Detect-cable-faults-More/152587007700 The only scope I have is the Hantek 6022BE 2 Channels 20MHz 48MSa/s HM. Is this scope fast enough? |
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