10.1 Scope. This Appendix provides general information to
construct a unctional test fixture to measure the core
sensitivity and linearity. This Appendix is a mandatory part of
the specification. The information contained herein is intended
20. APPLICABLE DOCUMENTS This section is not applicable to
DESCRIPTION AND CONFIGURATION
30.1 General. The information defined herein includes the
tests required verify the capability of the toroid core. The
test tolerance on absolute magnetic values is ± 5%.
30.2 Test circuit. Figure 1 shows a block diagram of a test
circuit used for core testing. This circuit consists of three
sections: excitation, envelope detection, and filter and gain. It
is an improvement over common signal detection circuits utilizing
a flux gate magnetometer. The circuit allows the core, when
subjected to the magnetic environment described in 30.4, to be
tested under operating conditions that simulate actual usage.
Proper calibration will allow the test circuit to operate
correctly without using standard cores for calibration.
Additional circuitry however, is required to process the output
from the test circuit for pass/fail indications.
30.2.1 Excitation circuit . The excitation circuit
schematic, shown in Figure 2, consists of a pulse generator, drive
transistors and current limiting resistors. The Darlington
configuration of transistors Q1 and Q2 amplify the waveform from
the pulse generator to the high current excitation signal required
to saturate the 14 turn magnetometer (core under test). This
current waveform is critical and must be monitored for calibration.
The current waveform can be monitored by measuring the voltage
across the R2 resistor (TP2 to TPl) with TPl grounded. The
current waveform of Figure 3 should be observed. The repetition
rate and current amplitude are defined as:
= high level time = 30 us ± 10%
repetition time = 1 msec ± 10%