DATE : 28/3/2002
METHOD:
Set up a test cct as shown. The "junk box" pot-core has thin
wire on the primary with a fairly large number of turns. The secondary
is a much thicker wire with an unknown but presumably fewer turns. A signal
of frequency 400 Hz was applied to primary and secondary sides and the
voltages under s/c and o/c conditions were measured with a HP 400H VTVM
RESULTS
Part 1/
| v1 | Vz1 | S2 | V2 | Vz2 | S1 |
| 8.0mV | 2.5mV | o/c | 120mV | 4.9mV | o/c |
| 7.9mV | 3.8 mV | s/c | 120mV | 4.4mV | s/c |
The Z-parameter equivalent impedances for 400 Hz cct will appear as
in figure (A) and, assuming the circuit is entirely inductive, the equivalent
inductances are shown in (B)
In order to attain a BW of around kHz, calculation indicates that a
series resistor of around 180R should do the trick.
Part 2/
DISCUSSION