THE C. E. COX COMPANY MODEL TC-1-P2, "MINITRACE II", IS A CONTINUITY TEST SET SPECIFICALLY DESIGNED FOR APPLICATIONS IN TELEPHONE SWITCHING OFFICES, ESPECIALLY OPERATING OFFICES, WHERE CONTINUITY TESTS USING AN OHMMETER COULD PROVE INEFFECTIVE, INACCURATE, OR EVEN DETRIMENTAL TO GOOD TELEPHONE SERVICE, AND DAMAGING TO THE METER. THE MINITRACE HAS SOLVED ALL THE PROBLEMS POSED TO OHMMETERS IN ACTIVE ENVIRONMENTS, AND OFFERS SEVERAL DISTINCT ADVANTAGES:
PRE-SET RESISTANCE THRESHOLDS
The MINITRACE II comes with two field presettable continuity thresholds for rapid go/no go line resistance tests that are acheived without reading a meter, which is slower and prone to errors. The MINITRACE II avoids these problems by comparing line resistance with the presettable thresholds, and using two distinct audio signals to indicate not only continuity, but whether line resistance lies above, below, or between the two threshold values. The audio signals appear as tones in installers' headsets.
AUTOMATIC OFFSET COMPENSATION
In operating offices, long lines may lead to voltage drops, or offsets, along the line. An ohmmeter would yield erroneous results in attempting to verify continuity under any such conditions. The MINITRACE II incorporates a compensation circuit to adjust the MINITRACE II inputs to match the offset and enable a valid test. The range of offset compensation is -10 VDC to +6 VDC. AUTOMATIC OVER-VOLTAGE INHIBIT
If the MINITRACE II encounters a potential beyond its voltage offset range, an alarm tone is produced, and the test is inhibited. Thus the MINITRACE protects itself and the circuits it tests. An ohmmeter could create operating defects in the system or sustain damage to its own circuitry. NOISE FREE TESTING
An ohmmeter, if placed across operating pairs, would produce sudden DC potential changes and changes in line impedance, appearing on voice-grade lines as pops or clicks, and on data lines as error bits or drop-outs. The MINITRACE II avoids this by generating a smooth, shaped test pulse that remains on each line only momentarily, providing a test that has no effect on the transmission quality of the lines, and is noise free. COMMUNICATION PAIR
The MINITRACE II incorporates a filtered 10 VDC source with phone jacks and binding posts to set up a clean, stand-alone communication pair for installers who are conducting tests on long lines, and are separated by some distance. The communication pair is also used to carry the audio signals indicating continuity. NO BATTERIES
The MINITRACE II operates on 115 VAC line current, and contains no batteries to go dead. Still, the test set is small, only 7.25" x 7.25" x 4.74", and weighs approximately 3.5 lbs. It is attractively packaged in a black case with handle, and is rugged and dependable, and simple to use.