Realtime High-Current Power Monitor

Thread Starter


Joined Jan 25, 2013
I've got a rather high powered stereo (4KW) in my car, built for high volume - but the car electrics is a major player in achieving high output so I'm making a real-time power monitor (to view peak power inputs to the amp, and system voltages).

Below is a proto I've whipped up that:
  • Can be turned on/off via a 2.5mA 5V DIO feed "SYSTEM ON"
  • Utilises 4th Order Sallen-Key for Anti-Aliasing the ADC sources (The car will naturally have significant line voltage spikes and resonant noise)
  • Uses a current transducer from LEM to measure a peak current of +/- 600A
  • Has an overall system power draw (when on) of less than 100mA (not including the uC) and less than 1mA when off.
Looking for some comments or notes from gurus about system design, if it looks OK, if there are improvements to make and so forth...

Thanks in advance.


Joined Apr 24, 2011
Relax. Close your eyes. Think peaceful restful thoughts. Let everything you know about your circuit drift away. Let it be forgotten.

Now open your eyes and look at your schematic. See the problem?

Thread Starter


Joined Jan 25, 2013
Well, ADC2 is measuring the -ve from the Amp (pointless). In fact I might just remove that altogether since I'm already getting that feed from ADC1 (ADC2 was going to be the AC input speaker-side and somehow got left in there).

Other than that, I don't see anything; did you spot something I didn't?


Joined Feb 24, 2006
I think he was trying to tell you that he(we) can't spot anything because your diagram is unreadable. It needs to be in a scaleable format.