1, Indicating measuring instruments
a, Moving coil meter
b, Moving Iron meter
c, Electrodynamic meter
d, Oscilloscope
2, Bridge cirquits
a, Balance, Unbalance bridge cirquit
b, Null type DC bridge cirquit
c, AC bridge cirquit
d, Transformer bridge cirquit
3, Potentiometers, Comparators
4, Processing Analog, Digital Signal