- on Test & Measurement
- Published in issue 7/2010 on page 74
AC Power Indicator
(Summer Circuits 2010 article)
The AC powerline indicator presented here has a complete galvanic isolation from the grid. The indicator is an LED that lights up when a current flows, although the current can be measured more accurately with an AC voltmeter set to its mV range. The detector is a transformer taken from an old mobile phone charger. The value of the secondary isn’t important because we only make use of the primary 230 V (115 V) winding.