Electronics > Projects, Designs, and Technical Stuff
Fox and Hound Upgrade
MarkPeeters:
Hello all,
I'm working on designing a fox and hound solution for long range cable tracing, I have reverse engineered a unit and found it just uses a single ended signal and ground. and it uses a 9v battery.
I would like to get more distance out of this as I work for an ISP and we still have some copper circuits out there, and are dealing with some long loop lengths that a standard fox and hound doesn't have the reach for.
so I was thinking:
- I could increase the voltage to get more reach by implementing a boost circuit or even just using two 9v batteries instead of 1
- or instead of a single ended signal, make it a differential signal, since that should double the signal level, and it's always a pair of wires.
Am I correct that either of these solutions would work? increase the voltage level, and/or make it a differential signal on the line? if so I would implement all of these and be able to switch between them.
OM222O:
Using 2 9V batteries = fried unit and components
I'm not sure how those units work, but I'd bet it's not just a "9v battery" across the line. Most likely it uses a specific frequency and looks for that in order to reduce noise. Differential signals can boost your signal integrity, so does reducing that frquency (AC gets coupled to parasitic capacitances and filtered by inductances, whereas DC passes right through). Ideally you'd have a high voltage DC source but if other things are plugged into the line when you connect that, you'd most likely fry something.
fordem:
The original Triplett Fox & Hound was an audio signal generator (2KHz I believe) and an audio amplifier with an inductive pickup - I don't recall them having any fancy filtering.
An ISP using copper lines - are we talking co-ax, twisted pair or good old fashioned POTs?
The old POTs system uses 48v DC signalling so anything connected to it will need to withstand that voltage, for that reason I don't see 2 x 9v batteries as being a potential issue and I don't see differential signalling as being effective for an inductive type pickup as used with most tone tools - the concept behind coax and twisted pair is that both technologies reduce "noise pickup", the corollary of which is "signal radiation" which is, so to speak, equally affected.
I don't mean to discourage you, but I've used tone tools from several manufacturers, including the original Triplett Fox & Hound as well as a couple of units from Paladin & Fluke specifically designed for CAT 5 UTP and not one of them was worth a damn in a "live" environment, not even the fancy Fluke Intellitone with digital signalling.
MarkPeeters:
I have build up the reverse engineered schematic I drew up.
The system runs at about 1Khz, and it's for the good old pots circuits, and some twisted pair (UTP) as well. The ones I have used in the past don't work well when there is dialtone or battery on the circuit, and the range isn't that far so it's not very usefull for long cable runs in the KM range. all I'm looking for is increasing the range.
any ethernet and pots equipment can handle 48vdc without any issues.
OM222O:
If you post the schematic it could be an easy upgrade: boost converter + replacing the drive element. But like I siad, post the schematic so we're sure.
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