# Questions tagged [joule-thief]

voltage boosting circuit.

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### How to reduce NPN reverse base current on this interesting "Super Efficient Joule Thief"?

Note: The question part is the fixing of the negative current at the transistor base. It looks like there's a problem with negative current at the LED(s) -- this is not expected to be answered in this ...
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### How can I measure the output of a voltage booster circuit?

I made this circuit, which was described on-line as a "transformerless Joule Thief." I was able to light four LEDs of varying forward-voltage in series, but I couldn't figure out how to use ...
240 views

### Is a balancing diode really necessary for the Balanced Boost converter?

Please pardon all of the information that precedes the question -- I didn't want you to actually have to go read the paper itself. This question is in two parts, but they are really equivalent, so it'...
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1 vote
370 views

### How to design a boost converter? (1.5V to 4V)

I want to build a circuit that powers 2 standard red LEDs (forward voltage of 2V each) from 1 AA battery. I would like to learn how to design and build a boost converter that can take 1.5V in and ...
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1 vote
111 views

### How to use YX8122 led driver?

I am building a small LED lamp from a jar(about 100ml), so all components should fit in it. I decided to use a LED drive/Joule Thief, that I found at online Chinese store. Datasheets (all I can find ...
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### Can I charge a super capacitor with a MPPT?

I already did some testing. I have a 220mW solar panel that charges a 3V supercap (takes a long time) which eventually powers my wifi module that needs ~1.5W (1.5 J/s) for 1 second then ~90mW (0.09 J/...
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1 vote
150 views

### Relaxation Oscillator LED Flashlight

I'm trying to understand the circuit presented in this video: https://youtu.be/qfgX93o8HzY?t=229 We states that when the power is first turned on, the left-most transistor has 0v at it's base so it is ...
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### Low voltage (self-oscillating) boost for solar powered pond pump

Long story shortened: I am currently designing a small filter for my pond using a small pump (6V-12V, upto 540mA) with UV-C LEDs parallel to it. Currently, it is battery powered (9V, 6x1.5V AA cells) ...
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### Simple self oscillating flyback converter [duplicate]

Please am studying about switching power supplies, starting from the simple ones. I've just concluded on joule thief and blocking oscillator, now am progressing to Self oscillating flyback converter(...
1 vote
140 views

### I want to design a joule thief circuit with input of 2mV and output 1.5V

I want to design a joule thief circuit having an input of 2mV and output of 1.5V. I searched for low input joule thief (JT) and I found that by using ALD110800/ALD110900 (they have zero threshold ...
325 views

### How do I simulate this unconventional Joule Thief?

Here is a transistor-based simulation of the manually-commutated switched-capacitor SMPS circuit discussed at the bottom of this question, that helps me to think and verify the performance of this ...
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1 vote
301 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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### 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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### 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-...
501 views

### Single Cell LED boost Converter

I am planning on powering 10 white LEDs (LUXEON 3014) from a single AA rechargeable battery with Vin min=0.9V, Vin max=1.4v VLed=2.8v @ 23mA so total Vout for 10 LEDs Vout=28v, iout=23mA I found this ...
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### Understanding a Single Transistor Flyback Transformer Driver?

I've been watching a few analyses of CRT flyback transformer drivers and can't understand why the transistor would shut off. To my naive perspective, it appears that the transistor should never shut ...
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### 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. ...
611 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 ...
1 vote
470 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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### 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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### 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 ...
1 vote
1k 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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1 vote
621 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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### 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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### 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 ...
313 views

### How calculate inductor discharge time through LED?

UPDATE Overnight I realized I'd been sleeping as I read part of the textbook I've been using or at least didn't quite fully grasp the purpose of inductor volt-second balance. I added the results of ...
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### 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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1 vote
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### 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 ...
1 vote
560 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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### 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 ...
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### Regulated Joule Thief: why it works?

Please explain to me why this circuit can give me a regulated 5 V? I understand the Joule Thief part, but why the regulator part work? simulate this circuit – Schematic created using CircuitLab ...
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### Joule Thief - operation and the 'supercharged' version

I've made a Joule Thief, and it works fairly well, but not as well as I would like. It's powering a 3.2v LED from a 1.2v battery, but it's very dim. I'm hoping that increasing the voltage from the JT ...
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### Checking materials (cheapest possible) to be used for a solar dark-detecting LED light bulb circuit

I want to make this circuit, which is from evilmadscientist.com and includes a Joule Thief: It's for a solar dark-detecting LED light; and I'm trying to follow this guide: https://www.instructables....
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### Alternative fix to: How can I calculate a Joule Thief

This is based on the original question: How can I calculate a Joule Thief. Since the gain of common emitter voltage amplifier and it will depend widely on the dynamic frequency of the LC unit, either ...
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### How can I calculate a Joule Thief

A Joule Thief is a simple step-up converter with which you can drive a 3.6 V LED with a 1.5 V battery even if it is spending the last drops of its life. It merely consists of a transistor, a ...
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