Uploaded December 2020 | Updated September 2026, 2 weeks ago

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Here is a super=simple technique to use time-domain-reflectometry (TDR) with your scope, a battery and a resistor, to measure the length of coax, twisted pair wires, Ethernet cable (Cat5, Cat5e, Cat6, etc.), zip-cord, etc. Previous videos on transmission lines, reflections and TDR measurements are here:
Transmission lines, reflections and terminations:
youtube.com/watch?v=g_jxh0Qe_FY
Basic TDR measurements with a scope:
youtube.com/watch?v=Il_eju4D_TM
Cheap TDR with Schmitt Trigger oscillator:
youtube.com/watch?v=9cP6w2odGUc
Notes from this video:
qsl.net/w2aew/youtube/SimpleTDR.pdf