2014-08-28 Waste AAA Cell Runs Germanium Joule Thief

I was out walking and saw three AAA cells in the street.  All three had been run over by cars, possibly several times;  most likely someone discarded them when their camera or whatever had said the batteries were too low.  I picked  them up and brought them home, and put them to good use at running my Joule Thiefs.IMG_20140828_083410S5

The mutilated cell can be seen in the photo.  It’s crushed, smashed and dented until it’s more oval than round.  But it’s still putting out power and has been running the Joule Thief since yesterday evening, about 12 hours and is still going strong.  Of course it helps that the Joule Thief uses a germanium transistor, which will run far below the 0.5 to 0.6 volts of the typical silicon transistor.   The typical germanium Joule Thief will run the cell down to less than 0.2 volts.  One issue I’ll have to deal with is that the seals of the case have probably been broken and the cell might leak its juice.  Not a good thing for whatever it’s laying on.

4 Responses

  1. Paul says:

    I looked at my online store. Germanium transistors are just not available. I would have thought they might have a current niche, but it seems not. It is a shame as I would love to have some to try. I’m surprised that silicon has taken over so completely but I am aware of the reasons why it has happened. Paul

    • admin says:

      I’ll email you with a reply.

      • Hans Heidmann says:

        Hi, I have recently spent many hours reading through your blog posts! They’ve been extremely helpful for someone like me with no electrical engineering experience in college – aside from the physics courses I was required to take for my computer science degree, and what I have learned though my own experimentation with electricity, which mostly involves the use of micro-controllers.

        Like the above poster, I am also interested in trying some Geranium transistors within my experimental circuits but they all seem to be so damn expensive (for a senior in college ha) ! If you could point me in the right direction, in terms of vendors and to learn more about the different types, I would really appreciate it! My only experience using transistors thus far has been making Joule Thieves with the easy to find silicon ones as a flyback v booster.

        Hope to hear back soon and thanks for all your blog posts.

        • admin says:

          Hans, I’m very pleased to find that someone has found my blog useful. Thank you. I found some inexpensive PNP germanium transistors on eBay, but that was a few years ago. The sellers are often eastern European and sell transistors made in Russia or the former Soviet bloc countries.

          But you don’t have to use germanium, and there are germanium NPN transistors (but they may be expensive too). Instead, you can use JFETs or MOSFETs. I’ll add some links to my blog.

          Here is one that uses a MOSFET.

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