Progress page and more

I just added a Progress page where we will keep track of what still needs to be done.

Also, we've gotten a few questions about the possibility of a 240-volt international version of the EnerJar. To make the EnerJar work on 240 volts, all that is needed is to change the value of a single resistor. The code will be exactly the same, because of the calibration that we are working on.

In response to another question, at the moment, we are not planning on selling prebuilt EnerJars. We may reconsider after the design is completed and we begin sourcing parts, but if you want an EnerJar but have no soldering skills, we recommend making friends with an electronics geek. They are pretty handy to have around.

Higher Resolution

Can you provide instructions for measures FRACTIONS of watt ? IE I need to measure less than 1 watt increments! I am converting to LED lighting in my home and am having NO luck in finding a watt meter to measure watts this low (.1 to 7 watts) accurately. I would love to find or build one (I have BASIC soldering skills) that can measure to at least 1 decimal place accurately preferably 2 decimals.

Suggestions?

Re: Higher Resolution

If you aren't going to be measuring high wattage, you can increase the resistance of the current sensing resistor (R7). The one I am using is about 0.004 ohms, if the highest power you want to measure is 20 watts or so, you could probably go to 0.1 ohms or even higher. At this resistance you should probably use a real resistor instead of a length of wire (unless you get very fine wire, which I wouldn't recommend).

Other than that, you will probably have to adjust the gain setting resistor (R8) to an appropriate value. You might need to change the PIC code, since I'm not sure if Zach is allowing for such a huge range when calibrating. If you don't have a PIC programmer, we will be selling pre-programmed chips once we work out a few kinks (see our progress page).

Thanks for your interest and let us know if you have any more questions!