Refer again to Figures 11.27 and 11.28. Current is fed to a special transformer
via a power amplii er from a 1.6 kHz constant-voltage oscillator. This current
is detected by a detection current transformer (CT). Only the 1.6 kHz signal
frequency is amplii ed by a i lter amplii er before being fed into analog/
digital (A/D)-converter, and after synchronous rectii cation it is displayed
on the liquid crystal display (LCD).