Welcome to EnerJar.net!

Well, we've finally launched a real website! As you can probably tell, we're not totally done with the site but we have posted preliminary schematics and source code. We will be updating the site as we solidify more of the design. If you want to stay updated on our progress, subscribe to our RSS feed or leave a comment below saying that you want to be on our mailing list. If you run into any issues with the site, email: admin {at) enerjar [dot} net.

your EnerJar

Hi matt!

your enerjar project is cool.. though why cant we use common op-amps here like LM358? or LM324?


My guess is that this is a device given by miserly parentals to a subteen to make them feel guilty for leaving the lights on. "See Bobby, your Game Boy Advance is costing us 53 cents a month!"

You could use it to prove to drunken friends that the wall warts do really use electricity when not being engaged.

I'm sure it is just one of many new anally- retentive products soon competing for our attention.

Nice project for my son and I

Congrats on your win. This will be a fun project to build with my son. Thanks.

I don't think you should have won

Why did you win? You just took a device that was already available on the market and put it in a jar. Wow, what an accomplishment. I think I will put a cord on my computer and call it my own. Save yourself the trouble and just by a Kill-A-Watt online.


So pleased to see this device. Please add me to your email list.
Thank you.


Congratulations on winning the competition! I've had a Kill-A-Watt on my wish list for a while now but I always prefer a DIY solution to buying a finished product. So I was very happy to find my way to your page from Slashdot.

I'm going to get started on my own EnerJar right away and I plan to attempt to modify the hardware to fit everything in one of the hundred-or-so large baby-food jars I have sitting around. It'll be a tight squeeze and I'll probably have to replace the PIC and display with smaller components, but I think it would be great if I could make it work. If I pull it off, I'll e-mail pics.

Thanks for having the imagination and initiative to get this idea to the masses! Please add me to your e-mail list.


Smaller PIC

very cool! It's good to hear from you. We are currently working on getting everything working on a PIC16F886 rather than the 877a. This should save a lot of space by going from a 40 pin double wide DIP to a 28 pin single wide DIP. We'll keep you updated by email.

A few quick suggestions

May I humbly suggest:
- That you add thick rubber gromits between the power cord and the metal lip of the holes in the jar lid? My concern is that you will find the metal has cut through and shorted the 240VAC.
- That you move to an enclosure other than glass? Glass tends to shatter when exposed to rapid heating, and with 240VAC going into the jar, there is an ample source of heating available.

Or at least that you add a note or warning to the description including those points...

...having said all that, congratulations and thank you for sharing your device.


I had a very similar idea but alas, I'm a lazy bum and don't really know that much about electronics.

So congratulations on actually making this happen.

Maybe this will get me started on my own project.




I 2nd the need for a 230V version!


way to bring power metering to the diyers.
any chance you'll post on instructables.com?

Congratulations on winning

Congratulations on winning the Greener Gadgets design competition, keep up the good work.


Cool, but what about a 220V

Cool, but what about a 220V version for the rest of the world??