Re: [EE] Isolated AC line current sensors

PZEM 004T modules are pretty cool if you don't want to roll your own design. The 10A versions use a current sense resistor, the 100A versions have a current transformer. They have optoisolated TTL serial in and out. You get voltage, current, power factor, RMS power. Under $10 from the usual cheap goods online stores.

Cheers, Bob


________________________________________
From: Piclist <[email protected]> on behalf of Harold Hallikainen 
Sent: Monday, July 21, 2025 5:05 PM
To: Pic List
Subject: [EE] Isolated AC line current sensors



I've been asked about sensing current on the AC line. Current transformers
immediately come to mind. Also, I see there are Hall effect based sensors
(similar to current transformers, but using a Hall effect device instead
of a secondary winding). For isolation, I also see linear optocouplers,
that have two photosensors so the LED current can be servoed. Another
method would be a current sense resistor with an isolation amplifier.

I remember years ago an LTC RMS to DC converter that measured the
temperature of a heater. It SEEMS like there could be a chip equivalent of
a thermocouple ammeter with an electrically isolated heater and a
temperature sensor.

Other ideas?

Thanks!

Harold