Holte Electronics Products
Passive cable locator with a differential antenna arrangement that is immune to disturbances from long wave radio transmitters. The differential antenna arrangement is a rod (tube) with two antennas that counteract each other to nueutralize airborne radio signals at the ends. The radio signals are, however, received indirectly via near by cables (cables act as antennas) and contribute to to their locatability.
DiffAnt solves the problem with disturbances from long wave radio transmitters. The cables are located by means of the otherwise disturbing radio signals. In this way we have succeeded in turning a problem into an advantage. The antenna rod (tube) is made of polycarbonate (Lexan) which is a very light, strong and shockproof material.
With sender rod CableAnimator placed vertically a suitable distance (10-20m) away, CB DiffAnt can also be used as a metal detector for hitting e.g. burided manhole covers. The vertical field from the CableAnimator induces eddy currents in metallic objects. The secondary field from an eddy current counteracts (weakens) the primary field locally, and an imbalance increasing the received signal level considerably is created when one of the antenna pick up coils comes near a metallic surface (e.g. manhole cover).
For a more precise description, user hints and technical data see:
CB DiffAnt brochure
CB DiffAnt 1m long, 400g light!
with user instructions on the front
CableAnimator is a simple transmitter (signal injector) shaped as a little rod (polycarbonate tube) to be placed on the ground across the cable to be stimulated. It induces a strong, easy to recognize pulsating signal in the cable. The useful range depends on the achievable coupling (distance from cable) and the inherent noise level - typically 200-300m with cables buried in normal depth and much more if it can be placed close to the cable.
It is powered from four AA-cells (6V) in an own battery tube connected with a short coaxial cable. Turning it on and off is made by attaching or removing the cable. This solution has been choosen in order to prevent that you forget to turn it off after use. The flexible cable also prevents dammage by bending. Both units are hermetically sealed and very robust.
Monitoring: Blinking red LED at the end of the rod, when the sender is active.
For more precise description and technical data see:
CableAnimator. From top:
Battery tube, power cable,
sender rod, and storage bag
Possible future add ons:
External display and loudspeaker unit:
A prototype of an external display unit with loudspeaker and signal strength indicator (pointer instrument) has been built and is used as a demonstration tool. It may be offered as an additional item in the future. This add on makes CB DiffAnt more similar to other cable locators and will be helpful for deaf and unmusical persons who are not able to hear tone pitch nuances.
Tube sonde (pipe line localization transmitter):
A miniature transmitter(miniaturized CableAnimator) to be shoved into non conducting pipes has been sucsessfully tested and may become a new product, if there is sufficient interest.
Metal (manhole cover) detector
CB DiffAnt is converted into a metal (manhole cover) detector with a signal source (tube sonde) placed on the rod in the neutral point between the two antennas. The fine balance between the antennas is upset, and the signal level increases significantly, when one of them comes near a metal surface. Manhole covers and similar objects are easily detected through 20-30cm ice or snow or soil.
It is also possible to use CB DiffAnt as a metal detector by placing the CableAnimator vertically 10-20m from the search location. The fine balance between the two antennas is upset and the airborne pulsating signal comes through, wenn one of the antennas is near a metal surface.