Search Results For:joule thief

2017-08-16 Joule Thief Measurements Of YouTube Video

I watched this YouTube video.  I liked it, it’s a well made video.    The author asks a question about the 9 min point.  He was not sure why the voltage peaked out at about 40 volts, and then stayed the same. First, it is not wise to disconnect the LED load from the JT because

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2009-01-10 Experimental Joule Thief

Date 2017-01-12 Link to Experimental Joule Thief

2016-10-04 Joule Thief Powers Field Strength Meter

There are many circuits that are used infrequently that are powered by the usual 9 volt battery. One of these happens to be a field strength meter (FSM), which is used for detecting the power output of a transmitter such as the one a radio amateur uses. Some FSMs are very simple and use no

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2016-09-28 Battery keeps Joule Thief Lit

I put this AA cell, which measured 1.3 volts – ‘dead’ – on one of my germanium Joule Thiefs more than a week ago. It was glowing very brightly for a few days. For the last few days, it has been weakly glowing, and the Kirkland AA cell is still hanging in there, even though

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2016-02-23 Joule Thief With Daylight Shutoff

I designed my Blue Blinky with a daylight shutoff, using a LED as the light sensor and an additional transistor to amplify the minuscule current that the LED puts out.  This worked just great because there is the point across the timing capacitor where the current is very low, and it takes very little current

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2016-01-19 Weird Joule Thief With No Resistor

I found this on YouTube.  It has no resistors, no capacitors, just two transistors and two inductors.  And and a 1.5V cell and LED of course. I redrew the topsy-turvy schematic that was shown at the beginning.  It was confusing with the minus on the left and plus on the right.  It makes more sense

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2015-12-25 Joule Thief In Mainstream Media

Merry Christmas!  Happy Holidays, too. I found this article, to my surprise, in a summer issue of Pop Sci magazine.  I was surprised because when it came to mainstream media, I thought that the Joule Thief was a best kept secret; hardly anyone other than ‘techies’ knew about it.  But here’s proof otherwise. I think

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2015-12-16 JFET Joule Thief

I captured this off a video and tried to make it a bit more readable.  I think it was from Sanjev. I built it and it does work at 40 millivolts.  The 2SK170 JFETs are not common, and may be difficult to obtain.  Other JFETs can be used, but I haven’t tried them.  I wrote

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2015-11-30 Low Power Joule Thief With Daylight Shutoff

This has been blogged, here and here.  I added a CdS photocell (resistor with a circle around it) to shut it off during daylight, thus conserving the AAA cell.  I used a 100k resistor for the base bias, so it draws very low current from the cell.  I can then call this a low power

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2015-10-29 Joule Thief Brightness Measurements

It’s been awhile since I blogged this, so I may be saying what I’ve already said before.  But I get comments from others about how to make measurements of the LED brightness.  A recent one is in the comments of an older blog.  Many Joule Thief builders don’t have the minimum tools needed for some

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