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Author Topic: Is that a joule thief?  (Read 72728 times)

Groundloop

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Re: Is that a joule thief?
« Reply #45 on: April 30, 2013, 06:24:54 AM »
My JT battery voltage is now [30.04.2013 0630] at 1,147 Volt. This is a drop of
0,157 Volt during 9 hours. The LED is light very dimly.

GL.

Groundloop

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Re: Is that a joule thief?
« Reply #46 on: April 30, 2013, 05:36:30 PM »
My JT battery voltage is now [30.04.2013 1730] at 1,032 Volt. This is a drop of
0,115 Volt during 11 hours. The LED is light very very dimly. So, how long until
we reach zero Volt on the batteries?

GL.

TinselKoala

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Re: Is that a joule thief?
« Reply #47 on: April 30, 2013, 05:38:19 PM »
I dunno, I'm too lazy to plot the curve and project it out. But won't your JT stop oscillating at around 0.4 V or so?

Groundloop

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Re: Is that a joule thief?
« Reply #48 on: April 30, 2013, 07:09:15 PM »
I dunno, I'm too lazy to plot the curve and project it out. But won't your JT stop oscillating at around 0.4 V or so?

TK,

A typical JT can't start to oscillate if the base voltage bias is below the level needed by the transistor, but
once started, the oscillator will happily oscillate down to 0,1 Volt because the pulses in the trigger coil
is higher than the approx. 0,6 Volt base voltage needed to trigger the transistor. That said, my LED brightness
is now down to almost nothing. So I think I will stop the drain down test soon.

GL.

Groundloop

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Re: Is that a joule thief?
« Reply #49 on: May 01, 2013, 05:44:36 AM »
My JT battery voltage is now [01.05.2013 0530] at 0,970 Volt. This is a drop of
0,062 Volt during 12 hours. The LED is light very very dimly, almost off.

GL.

Groundloop

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Re: Is that a joule thief?
« Reply #50 on: May 01, 2013, 04:30:31 PM »
My JT battery voltage is now [01.05.2013 1630] at 0,949 Volt. This is a drop of
0,021 Volt during 11 hours. The LED is light very very dim, almost off.

GL.

TinselKoala

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Re: Is that a joule thief?
« Reply #51 on: May 01, 2013, 05:47:30 PM »
Have you considered making a light-level sensing instrument? I am impressed with the performance of the NTE3037 phototransistor; it would be fairly easy to make a light output meter with this as the sensor and a regulated supply from a 78L05 mini-regulator.
There are also some complete lightlevel sensors-on-chip like the TSL235R that would make a neat addition to a JT workbench setup.

Groundloop

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Re: Is that a joule thief?
« Reply #52 on: May 01, 2013, 07:30:40 PM »
Have you considered making a light-level sensing instrument? I am impressed with the performance of the NTE3037 phototransistor; it would be fairly easy to make a light output meter with this as the sensor and a regulated supply from a 78L05 mini-regulator.
There are also some complete lightlevel sensors-on-chip like the TSL235R that would make a neat addition to a JT workbench setup.

TK,

It would probably be nice to have a a light-level sensing instrument, but in this test I do not need it.

This test is to see if is it possible to fully drain a battery down to zero Volt. My theory is that this
is not possible, not even with a short. The battery will always go back to some low voltage. So my LED
is there to see if the circuit runs or not. But if I find a way to light a LED to some higher level,
using "dead" batteries, then a light meter could be used to measure the output.

Do you know any IC that can light a ultra bright LED to a reasonable light level from a very low
input voltage, say 0,1 to 0,5 Volt or so?

Added: I just found one. The LTC3108 can operate down to 20mV input. Data sheet attached.

GL.

Groundloop

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Re: Is that a joule thief?
« Reply #53 on: May 02, 2013, 10:36:15 AM »
My JT battery voltage is now [02.05.2013 1030] at 0,931 Volt. This is a drop of
0,018 Volt during 18 hours. The LED is light very dim, almost off, and is flickering.

If I touch almost any parts of the circuit, then the LED goes off. Yesterday [01.05.2013 2300]
the voltage was 0,925 Volt. So the voltage has increased somewhat during the night.

GL.

conradelektro

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Re: Is that a joule thief?
« Reply #54 on: May 02, 2013, 10:52:56 AM »

Do you know any IC that can light a ultra bright LED to a reasonable light level from a very low
input voltage, say 0,1 to 0,5 Volt or so?

Added: I just found one. The LTC3108 can operate down to 20mV input. Data sheet attached.

GL.

@Groundloop: a poster named magpwr showed a circuit and the transistor 2SK170 which lights a LED dimly down to 30 mV input power, I could do it with 50 mV.

Attached you see the circuit based on this transistor.

Greetings, Conrad

Groundloop

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Re: Is that a joule thief?
« Reply #55 on: May 02, 2013, 11:21:48 AM »
@Groundloop: a poster named magpwr showed a circuit and the transistor 2SK170 which lights a LED dimly down to 30 mV input power, I could do it with 50 mV.

Attached you see the circuit based on this transistor.

Greetings, Conrad

Hi Conrad,

Thanks for posting this, I will study the data sheets for the components.

GL.

Groundloop

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Re: Is that a joule thief?
« Reply #56 on: May 02, 2013, 08:17:44 PM »
My JT battery voltage is now [02.05.2013 2018] at 0,893 Volt. This is a drop of
0,038 Volt during approx. 10 hours. The LED light is steady and very dim.

GL.

Groundloop

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Re: Is that a joule thief?
« Reply #57 on: May 03, 2013, 08:21:34 AM »
My JT battery voltage is now [03.05.2013 0818] at 0,888 Volt. This is a drop of
0,005 Volt during 12 hours. The LED light is flickering and very dim.

GL.

Groundloop

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Re: Is that a joule thief?
« Reply #58 on: May 03, 2013, 08:30:32 PM »
My JT battery voltage is now [03.05.2013 2018] at 0,889 Volt. This is a increase of
0,001 Volt during 12 hours. The LED light is flickering and very dim.

GL.

Groundloop

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Re: Is that a joule thief?
« Reply #59 on: May 04, 2013, 10:47:19 AM »
My JT circuit did stop oscillating tonight. No light in the LED and no signal received in my spectrum analyzer.
The battery voltage today was 0,885 Volt. My next attempt to fully drain the batteries will be a J-Fet circuit
(as posted by Conrad). But first I have to find some J-Fet transistors.....................  :-)

GL.