Joule Thieves ......

So the last two weeks I haven't written this blog,even though my resolution was to write once a week.But there you have it.....In that time I have looked into new Joule Thief circuits and ways to power them.For example there is the cement battery,the Magnesium battery etc.Also I have made my first pancake coil.And the result seems to be that it works better than some coils,depending on the size and number of windings.
The coil is a Nikola Tesla patent: