Questions tagged [joule-thief]

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Joule Thief powered HC-SR501 PIR Motion Sensor & LED string

Following BigCliveDotCom's YouTube video, I was able to build a joule thief. I then built a HC-SR501 PIR Motion Sensor lighting a 4.5v string of LED fairy lights powered by either a 5v wall wart. or ...
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1answer
115 views

What's wrong with joule thief circuit? [closed]

Transistor 2n3904 Homemade transformer with 10 turns Power supply 1.5 v Schematic: I think the toroid winding shorts the power supply as it happens with my buck converter. I think the toroid ...
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3answers
132 views

What is a power factor correction choke (PFC choke) and how does it work?

They Exist This Link at Newark displays "Power Factor Correction Chokes", which I did not know existed. I have a linear motor which I suspect really needs power factor correction. Please tell me ...
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0answers
62 views

Charging a big capacitor from a weak power supply

Let's say I need to charge a 4m7 (4700uF) capacitor to 5V, from a 1.5V battery with an internal resistance of 100 ohms. I'm trying to use a typical transformer joule thief with something like soft-...
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1answer
326 views

How do I calculate the power consumption when my circuit draws AC and DC current and I only have a cheap DMM? (Joule Thief) [duplicate]

:) So. How do I correctly calculate the power consumption of this circuit? :) I don't have an oscilloscope or an DMM that measures I. My DMM is an Extech EX330, which is quite good for it's price. ...
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3answers
460 views

Why does DMM show AC and DC current when source is a battery? (How to calculate power in this case?)

The circuit is an altered Joule Thief of my design that is driven by an AA or AAA battery. I’m observing the current at the battery anode with my DMM in series. (Extech EX330) This circuit is ...
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1answer
261 views

Efficiency question of # of LEDs for 6 volt 4 cell Joule Thief Flashlight circuit

This is a high voltage Joule Thief circuit simulation I developed in LTSpice. I am sure that it qualifies as a true Joule Thief because, in the picture below, we are zoomed into the "dead" voltage ...
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2answers
289 views

The Joule Thief is what kind of oscillator? Armstrong? Relaxation? or what? Thanks!

On Wikipedia, the Joule Thief is described as being an Armstrong oscillator, which I strongly believe it is not (because it has no capacitor). But the Wikipedia article tries to back up this ...
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2answers
2k views

Understand the Joule Thief circuit

I quote from Wikipedia (https://en.wikipedia.org/wiki/Joule_thief): ... This self-stroking/positive-feedback process almost instantly turns the transistor on as hard as possible (putting it in the ...
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2answers
525 views

Cannot get joule thief to work

For a few weeks now I've been trying to construct a joule thief using a schematic commonly found on the web as seen in this url: It consists of an npn transistor, a 1k resistor, two coils wound ...
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2answers
381 views

5V UPS circuit with NiMH joule thief backup

I'm trying to design a UPS circuit for microcontroller backup. Require 3.7-5V, and less than 50mA for 10 seconds every 15 min. Power cuts in my area are never longer than 3hours, and occur rarely. I'...
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2answers
384 views

Joule thief point

I have this circuit from a flashlight that runs an LED with just 2xAA batteries. Initially I thought it used a boost converter or a joule thief but when I opened it up I found that it did not. It ...
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1answer
266 views

Joule Thief - Why only single celled?

According to this Wikipedia article: It can use nearly all of the energy in a single-cell electric battery, even far below the voltage where other circuits consider the battery fully discharged ...
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1answer
1k views

How a Joule thief works?

I think this website explains a Joule thief in a wrong way: http://buju357.blogspot.com.eg/2013/06/joule-thief-theory-of-opperation.html The website says: "The increasing collector currentflowing ...
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1answer
1k views

lighting up a led with 30 millivolt-0.1 volt with joule thief?

I want to light up a led with my hand heat by using a peltier cooler. how can I light up a led with 30 millivolt-0.1 volt with a joule thief? Should I connect more transistor in parallel or give more ...
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1answer
411 views

Most efficient way to generate 3-4 volts from less than 0.5 to 1.5 volts

I am looking for a way to convert power from a 1 farad supercapacitor charged by a solar cell into enough voltage to power an LED. The supercapacitor will contain up to 2 volts from the solar cell. I ...
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4answers
2k views

Is there any benefit to using a voltage booster (such as Batteriser) on “dead” batteries?

The Batteriser [Edit: removed dead, harmful link] is a crowd-funded product intended to extend battery life by boosting the voltage. It is basically a joule thief that is in a tiny package that slips ...