MisterBill2
- Joined Jan 23, 2018
- 18,566
What sort of cables are those with such high characteristic impedance? I can see a cable with the pairs joined at the far end and then a magnetic probe stuck between the conductors inducing a voltage in a pickup coil. Really a good scheme. And with an isolated drive current it can detect damaged insulation as well. And we will not be matching impedance to 3 or 4 significant digits. So two transformer windings like I mentioned will work well.Well, the impedance of most cables is in the range of 50 to a couple hundred ohms. And if I were making a cable identifier, I think would actually want a constant current source. You start with the worst case length and type of cable, and how much signal you need to be able to detect it at the far end, work backward from there. Also this seems like the sort of thing that would be better
Well most cables have impedances in the tens to hundreds of ohms. 50 to 150 ohms would probably cover a good bit of the cable out there.
As to signal strength, I guess it depends on how long the cable is and what you're using to pick it up at the far end. But I can't imagine needing even one watt. Personally, I think I would go with the current source which would self-limit if there was a short.
Also, this seems like the sort of thing that would be battery powered. If so then why would you need isolation? Isolation from what?