We report on a novel electrical current-sensing principle based on wavelength-encoded modulation of the ultrabright green (at 525 nm) light-emitting diode (LED) transducers. It complies with the optical subsystem of a hybrid current transformer . Real-time wavelength demodulation is performed with the passive spectral edge filter OG 530. Linear calibration plots were achieved with -0.33 nm/mA for dc and +0.99 mA/sup -1/ for ac current sensitivity, respectively. A measurement accuracy of 1.3% for 28.4-mA ac peak current range is achieved. A simple theoretical model is outlined. Issues such as electronic and thermal effects on stability performance are also addressed.