CONSTRUCTION OF ANCHORWATCH

The LOAD CELL is made from Aluminium bar-stock and the active part is a ring 22 mm outer radius, 14 mm inner radius. Four resistance strain gauges are attached to the inside of the ring so that, when the ring is stretched by applying the anchoring force, two of them stretch while the other two remain relatively unstressed. The gauges are connected in a Wheatstone bridge circuit supplied with 5 volts from the CONTROL BOX. The out-of-balance potential (a few millivolts) from the Wheatstone bridge is converted to a frequency. The frequency is measured and the information processed by an electronic chip to give a reading of force in kg.

SPECIFICATIONS OF ANCHORWATCH

Operating Voltage	9 - 15volts
Current drain	80 milliamps
Prestressed tension of LOAD CELL	1500 kg
Maximum operative load reading	999 kg
Negative load reading	to minus 999kg
Zeroing Facility	Yes
Default Load Reading (on first connection to battery)	between -20 kg & plus 60 kg
Default Alarm Setting (on first connection to the battery)	500 kg
Accuracy	+/- 3% of Full Scale or better
Immunity to Radio Frequency Transmission	Immune to VHF transmission at 25W with aerial further than 2 metres from control box.
Radio Frequency Emission	10dB below permissible level.
Temperature Sensitivity	1kg/degree Centigrade or less
Waterproofing Load Cell	Fully Waterproof
Control Box	Splash resistant
Minimum breaking strain of shielded cables	20kg