The later part of yesterday and all of today was spent on getting the Hue efficiency & power meter linear at low levels. The problem ended up being very simple. My method of setting the software offset was wrong because of the instrumentation amplifiers common voltage. For like weeks I've been battling with the instrumentation amplifiers common voltage issues, and thought it was a thing of the past, but it decided to pay one last visit, LOL.
The correct method is the leave the Hue device battery connected, leave the Hue running, set the Hue device to produce low input current, and then short the 20 ohm resistor (it's used by the instrumentation amp to measure current). Yesterday I was doing the lazy man's method by simply disconnecting the Hue battery. My bad. :cry:
Now if the efficiency meter had one channel, like a DVM, then all of this is no problem, but that's not the case. The Hue efficiency meter requires 4 channels, and they all have a common ground. The easy solution is to use linear optocouplers. That's great, but I don't have those type of optocouplers.
Created on 2010-09-09 20:17:57 by EnergyMover
Electronics, Free energy, MCU, Science