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conradelektro

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #30 on: January 21, 2016, 02:34:34 PM »

I've recently been making some electricity-to-light efficiency tests and it's surprising how much actual brightness change has to happen before the eye can detect it purely visually.

I'm using an Extech LT300 light meter and a box which keeps the light sensor and the light source under test separated by a fixed, standard distance and excludes other light.

J.L. Naudin had to use a light meter in a box to see that the KAPAGEN was not OU:

http://jnaudin.free.fr/kapagen/

http://jnaudin.free.fr/kapagen/kapagen33io.htm

http://jnaudin.free.fr/kapagen/kapagen33pio.htm

Also the calibration was very important.


It is not easy to do meaningful measurements with a light meter. May be comparing the same light source under different drive conditions (in a box) is feasible. But the value of such a measurement will only be a "comparison", no absolute values.

Be aware of the following "feature" of the LT300: https://en.wikipedia.org/wiki/CIE_1931_color_space (CIE standard observer)

This is why I never bought a light meter. But they have become much cheaper and it is interesting to play with such a device.

Greetings, Conrad

nul-points

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #31 on: January 21, 2016, 11:04:05 PM »
Interesting diversion - thanks for your various inputs there, guys

Conrad is absolutely correct.....

...we don't need to know absolute values if we're comparing results in the same context


So - no need to hypothesize any further - the photometric intensity results are in!

As you would expect, the initial LED intensity is very close for both tests:- LED to ground; LED charging output cap - (because of course the output cap to be charged is at ground potential, initially)

The grounded LED peak intensity is slightly smaller at 98.5% of the full circuit peak intensity

But what about the average light intensity for each test?

If Conrad's theory is true  - ie. that the reason the full circuit illuminates the LED twice as long as the grounded LED is because the LED is dimmer,  then the grounded LED should have an average intensity about 2x the average of the full circuit LED

Here are the photometric intensity profiles for the initial 360 seconds of the two tests - remember that after 360 seconds the grounded LED has discharged the input source and stops illuminating, as expected;   however, in the full circuit, not only has the same amount of input energy been transferred via the LED but its current has also been used to charge the output cap and therefore the input & output storage devices can be swapped to allow the LED to continue its illumination ( & this process can be repeated one or more times, depending on the supply voltage & load current)

So - is one of the intensity averages 50% of the other?  NO!

The dimmer of the two tests is 92% of the other - they are approximately the same! 

I'll let any visitors here decide for themselves which profile is the grounded LED test and which is the full circuit test

These results are showing that, since energy cannot be destroyed, if we are careful about how we transfer energy from one store to another (ie. reducing the conversion of energy into a state which leaves our system) then we can use the energy transfer to perform work on each pass

This circuit is based on the principle that Energy is conserved - Work is not

Thanks for reading, testing continues
np


conradelektro

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #32 on: January 22, 2016, 01:39:10 AM »
So - no need to hypothesize any further - the photometric intensity results are in!

As you would expect, the initial LED intensity is very close for both tests:- LED to ground; LED charging output cap - (because of course the output cap to be charged is at ground potential, initially)

The grounded LED peak intensity is slightly smaller at 98.5% of the full circuit peak intensity

Here are the photometric intensity profiles for the initial 360 seconds of the two tests - remember that after 360 seconds the grounded LED has discharged the input source and stops illuminating, as expected;   however, in the full circuit, not only has the same amount of input energy been transferred via the LED but its current has also been used to charge the output cap and therefore the input & output storage devices can be swapped to allow the LED to continue its illumination ( & this process can be repeated one or more times, depending on the supply voltage & load current)

So - is one of the intensity averages 50% of the other?  NO!

The dimmer of the two tests is 92% of the other - they are approximately the same! 

These results are showing that, since energy cannot be destroyed, if we are careful about how we transfer energy from one store to another (ie. reducing the conversion of energy into a state which leaves our system) then we can use the energy transfer to perform work on each pass

This circuit is based on the principle that Energy is conserved - Work is not

@Nul-Points:

Very nice result and I am glad that you have proven me wrong. It is a good result, that one can store part of the energy for later use without dimming the LED.

I have to think why that seems to, but your test and the two graphs seem to tell the right story. I wonder where the energy goes if the LED is grounded? Something must become warmer?

If your result is correct it also means that one can make a pulse motor more efficient by feeding the back EMF pulse to a second battery (or cap) for later use (like swapping power source and storage).

And I wonder if one could feed back the back EMF directly to the drive battery in order to draw less power? The LED would shine longer without swapping batteries. Gyula posted the attached circuit in an other thread (as a principle, the important component is the bifilar wound coil, which would mean a third winding in the LED circuit). May be Gyula is reading this and would like to comment?

Greetings, Conrad

conradelektro

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #33 on: January 22, 2016, 02:00:23 AM »
Well, I thought about this strange similar light intensity graphs and came to a conclusion:

To make a meaningful comparison and to test what I meant, one should not ground the LED but put it how I show in the attached circuit.

So, test one: the LED is put in the place as I show in the attached circuit. Make the power graph till the LED goes out and make the light intensity graph.

Test two: the full circuit (with storage cap) is used and the power graph and the light intensity graph are already done. It is not necessary to this test again.

In this way we have a "true" comparison between a "normal circuit" and a "swapping circuit".

In the "swapping circuit" the LED is driven with the back EMF, but in a "normal circuit" one would drive the LED directly (as shown in the attached circuit).

And in the normal circuit the LED will be brighter for the same power draw as in the "swapping circuit". But the comparison is difficult, because it is difficult to cause the same power draw in both circuits.

The error in Nul-Point`s comparison and arguments: he always drives the LED with the back EMF and for sure, it always has the same brightness and a similar power draw occurs in the initial phase in both cases.

And I claim: even with Gyula's idea one can not feed back the back EMF (or swap it) in order to gain something. And in Nul-Points circuit one can light the LED longer (by swapping the batteries) but dimmer for the same power draw as in a "normal circuit". There are no miracles, and I started to believe in miracles for a few minutes till I came to my senses again.

Greetings, Conrad

citfta

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #34 on: January 22, 2016, 02:24:19 AM »
Hi np,

Thanks again for this nifty little circuit.  I am still playing around with mine and trying different LEDs and also tried the super caps except my "super" caps from China weren't so super.  They had a lot of internal leakage so that test was a failure.  I need to get some more super caps to try.

What you are doing with this circuit is what David Bowling has been talking about for the past few years.  You can conserve energy by running it into a load and charging another battery at the same time.  In the original 3 battery generating system as proposed by John Bedini there were 2 batteries connected in series and then to a load and the other side of the load went to a third battery that was connected with the polarity opposite the other two.  While drawing power from the two in series you were also charging the third battery.  As one of the two in series dropped in charge you then swapped it out for the fresh charged one.  Of course they all eventually went down,  BUT the run times were much longer than if the load was merely run off the 3 batteries connected in parallel.

As we have continued our testing we are now using a voltage boost module to raise the voltage so we can run a load and charge another battery using only one primary battery.  Almost identical to what you are doing only on a larger scale.  We are using as our load a scooter motor turning a generator to charge another battery or to run some other load.  We are getting very long run times by swapping the 2 batteries back and forth.  You can get even better performance by using one extra battery so that the one that has just been charged can rest before going back into the system.

No we don't have OU yet but any system that can extend your run time from the batteries by several times normal is worth seeing how far we can push it.

Carroll

nul-points

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #35 on: January 22, 2016, 08:36:35 AM »
Hi guys, first of all, thanks as always for your input

I think its time to address a few possible misconceptions....

Conrad,  i do see a flaw in the capacitor to capacitor tests ...but it may not be the one you imagined - my circuit has been intentionally arranged to ensure that the LED only conducts with flyback energy

The clue is in the naming: 'flyback flashlight'

Your proposed replacement of the LED will not work for any supply voltage below the effective forward voltage of the LED + circuit voltage drops (eg. 'On' voltage of Q1, IxR drop of L1, T1, etc)

In order to try and present a complete test, using the shorter runtimes which a supercap would provide, i was diverted away from my original requirement for LED biasing which ensured it received only flyback drive

I could repeat the test with the output capacitor pre-charged to match the input, as only this will be a true representation of a regular operating condition for my circuit but your proposed re-arrangement of the circuit is unsuitable as the white LEDs won't light at all for supply voltages below and away from their forward voltage (say below 2.5V approx?)


Carroll, thanks for the update, i'm pleased to hear that the David Bowling thread is actually producing some useful end-results

Maybe i need to repeat a statement near the beginning of my first post in this thread "Ok, nothing novel, there - except...."

I'm not claiming any originality for this concept here - these ideas go back a LONG way, well before Mr Bowling or i turned up on the scene!  :-)

The "except..." there refers to the fact that i've been measuring real gains with this circuit, whereas i've tried many times to get anything useful from the classic 'charge 2 parallel batteries from 2 in series" and also 'charge 1 battery from 2 in series' type approaches

...for example, in Prof Jones thread, back in 2011:
  http://overunity.com/10773/physicsprof-steven-e-jones-circuit-shows-8x-overunity/msg301808/#msg301808

That's great that you're finding real gains with that approach, i'd given up on it  :-)


This particular circuit, here and now, is my own development - a slightly ironic response to apparently over-hyped claims of OU flashlights for sale and horrendously over-complex (and under-unity?)  'self-running lanterns'

I wanted to show that you can achieve real gains with a fairly simple circuit, and as Itsu said it can be built and running over a weekend!

I try to provide a slightly different approach in my threads - low on hype, heavy on data, full-disclosure of circuit details

I've started to investigate the circuit performance in more detail, and on the basis of what i'm seeing, i plan various developments, not just flashlight/lantern applications

I'll just carry on - doing what i'm doing - and sharing what i'm finding with anybody who is interested in the same things


I wish you all you guys good success with your individual endeavours
np

itsu

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #36 on: January 22, 2016, 11:45:51 AM »

Ok,  i see i am falling behind in this thread, but my bat42 just arrived.   I will catch up later today.

I made a pcb with the 2x bat42's, BC547, 10x 10F supercaps, 100K pot, 10mm led, 100uF buffercap.
The 10x 10F supercaps a divided 2x 5 in series making 2 stacks of 2F caps, backed/loaded by 2x 750mAH 1.2V rechargeables for now.

I made a video of this, kind of in a hurry and unprepared, so it looks clumsy, sorry about that.

First 3 minutes describe/shows this new setup.
Then i show/measure something i don't understand (led pulls 5mW, while neither battery/supercap seems to supply this)
From 13 minutes into the video on, i show the rundown of the circuit with the 2x 2F supercaps only.

No free lunch here as expected.

Video here:  https://www.youtube.com/watch?v=VAa-AAEWXv8&feature=youtu.be

I have some screenshots of the power calculations on the led, and both batteries if needed.
Where does the power come from powering the led?  Is it because its kind of floating compared to ground, so a measuring error?

Regards Itsu

conradelektro

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #37 on: January 22, 2016, 02:12:01 PM »
No we don't have OU yet but any system that can extend your run time from the batteries by several times normal is worth seeing how far we can push it.

The problem is the comparison circuit. You say, that you can push the run time. That may well be, but you push it in comparison to what circuit? You push run time in comparison to what alternative?

If the goal is run time mainly disregarding LED brightness, longer run times can be achieved.

If the goal is "most light for the least input",  a circuit (although it pushes run time) might be a looser.

Like in all endeavours, success depends on the definition of the goal.


@Nul-Points:

You are of course right, my placement of the LED was not good for lower supply Voltages! It was late and I was not thinking straight. Sorry!

First argument: I do not know whether "grounding the LED" is the right comparison circuit in respect to your "full circuit". I suspect it is not, but I can not point out a good comparison circuit for supply Voltages from 2.2 Volt down to 0.6 Volt. May be I get an idea later on.

Second argument: For supply Voltages from 5 Volt down to 2.2 V I think I have found a good comparison circuit, which I attached. The important point is that the variable resistor is set to a value which makes the LED shine at 5 V as bright as in your "full circuit" at 5 Volt. From your graphs I take the Value of "0,4" for light brightness at 5 Volt (supply Voltage) for your "full circuit".

From your graphs we already have the data for your "full circuit", which is "LED brightness curve from 5 Volt to 2.2 Volt" and "run time from 5 Volt to 2.2 Volt". Now it would be nice to have this data also for the very simple comparison circuit.

The very simple comparison circuit would be the "normal way" of driving a LED which then can be compared (concerning LED brightness and run time) with your "full circuit". Unfortunately only from 5 Volt down to 2.2 Volt.

@Itsu and all thinkers:

Let's compare Nul-Point`s two alternatives, his "full circuit" and his "LED grounded circuit". My question: where does the energy go if the LED is grounded in comparison to the energy which goes into the storage battery (or cap)?

The run time in the "LED grounded circuit" is shorter and LED brightness is comparable for the initial duration. Where does the energy god if not into the LED? But the LED is not brighter?


@Nul-Points:

My ramblings are not intended as criticism. You have such nice measuring possibilities (data logger and LED brightness), therefore I see a chance that you can clarify many questions (and some of my questions might be stupid).

It is always difficult to follow the "energy". And like in all ways of life, what is compared to what? One should not compare apples and oranges.


Most efficient way of driving a LED in terms of most light output for the smallest energy input:

Adjust the power supply to a value (around 3 Volt) so that the LED in series with a 5 Ohm resistor gets exactly its nominal current (depending on the size of the LED between 20 mA and 200 mA, for some very small LEDs it is only 2 mA to 5 mA).
That is the "ultimate comparison circuit" for any LED driver circuit.

There is of course the practical wish to use a battery which Voltage decreases over time. There might be the wish to use only one 1.5 V battery, which makes an oscillating circuit necessary (to lift the Voltage to at least 3 V for the LED).

I would say that the oscillating circuit costs energy in comparison to the "ultimate comparison circuit". Some energy will be lost in the oscillation components (coils, transistor) and I suspect that the LED suffers (will break sooner) if driven by spikes much higher than 3 Volt.

I also would say that a battery stays about 90% of its run time between 1.5 and 1.0 Volt. Then it runs down quickly to near 0 Volt. Is it worth while to design a circuit for less than 1.0 Volt (it would only last 10% longer than a simpler circuit which works between 1.5 V and 1.0 V).

The simplest way of driving a LED pretty efficiently: use three AA batteries in series (they will start out at 4.5 Volt and run down slowly to 3 Volt in 90% of their run time), choose a resistor in series with the LED, so that the LED has its nominal current at 4.5 Volt. It is hard to beat that very simple circuit in terms of run time and light output per energy input.

Greetings, Conrad

conradelektro

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #38 on: January 22, 2016, 03:08:01 PM »

Where does the power come from powering the led?  Is it because its kind of floating compared to ground, so a measuring error?


I watched your latest video https://www.youtube.com/watch?v=VAa-AAEWXv8&feature=youtu.be.

Very nice setup!

I am sure you will find the right setting for your scope to measure the input power.

It may be, that the Current probe and the Voltage probe do not have the same ground while measuring the input Wattage?

The oscillations of the circuit might influence the ground of one of the probes and I suspect it is the Current probe, because it is an active one (while the Voltage probe is comparatively simple in terms of electronics).

Whenever I do scope measurements I find a new way of making errors. An electronics professor once told me that "measuring technique" is the high art in electronics and separates the masters from the apprentices. I am definitely a beginner apprentice. The better the scope the more errors one can make.

Greetings, Conrad

nul-points

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #39 on: January 23, 2016, 01:25:26 PM »
I feel that it's necessary to make the following statement below, BEFORE it becomes a necessity - i am grateful to ALL the members who have contributed so far - each have made some positive contribution in one way or another.  I have seen on previous threads (of my own and other members) how the main focus of the thread can get diverted and obscured by 'straw men' arguments, irrelevant comments and a high-jacking of the thread-owner's intended test 'plans', therefore...

****************
PLEASE NOTE:-

SINCE THIS THREAD DOESN'T HAVE THE LUXURY OF MODERATION, I ASK YOU POLITELY TO KEEP YOUR POSTS TERSE AND TECHNICAL, RELATING DIRECTLY TO DATA AND CIRCUIT INFORMATION PRESENTED BY MEMBERS WHO ARE TESTING REPLICATIONS OF THIS CIRCUIT

IF YOU WISH TO INTRODUCE AN ISSUE WHICH ISN'T EITHER A COMMENT ON DATA SHOWN OR AN ANSWER TO A QUESTION POSED BY A CIRCUIT BUILDER, THEN PLEASE  P.M.  ME TO DISCUSS IT FIRST

REMEMBER THAT THE PEOPLE AT THE BENCH WILL HAVE THEIR OWN 'SCHEDULE' OF TESTS PLANNED - PLEASE RESPECT THEIR JUDGEMENT AND PLANS BEFORE INSISTING THAT CERTAIN TESTS BE CARRIED OUT

EVERYONE IS WELCOME TO THEIR OPINIONS, BUT THEY REMAIN OPINIONS UNTIL PROVED OR DISPROVED BY DATA - THIS IS NOT THE THREAD TO AIR OPINIONS WHICH AREN'T A DIRECT INTERPRETATION OF THE DATA SHOWN

IF YOU BELIEVE STRONGLY ENOUGH THAT THE TESTS REPORTED HERE ARE MISTAKEN, MISDIRECTED OR MISINFORMED THEN GO AND START YOUR OWN THREAD, CREATE AN EXPERIMENT AND REPORT YOUR DATA

ANYONE WHO APPEARS TO ME TO BE IGNORING THIS POLITE REQUEST WILL FIND THAT I NOT ONLY REPAY THEIR EVIDENT RESPECT BY IGNORING THEIR POST(S) BUT ALSO WILL LIKELY TREAT THEM TO SOME OF MY ASCERBIC WIT INTO THE BARGAIN  ...(I AM OLD AND UGLY AND I NO LONGER GIVE A D@MN !)

YOUR 'VISIBILITY' HERE WILL BE DEEMED TO BE ACCEPTANCE OF THE ABOVE 'GROUND RULES'

OK - LET'S CONTINUE
**********************

nul-points

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #40 on: January 24, 2016, 03:49:56 AM »
I had some time, while my planned Friday overnight test was running into yesterday, to think about your original LED intensity question, Conrad

We know that there's no point trying to compare the circuit LED drive level witb a DC test setup because of course by the very nature of a pulse circuit, we have a duty cycle - and since this is a flashlight, and not a piece of test equipment, say, our user requirement is just that the flashlight should be 'bright enough' to illuminate what we need to see in the dark - our brain doesn't care if our eyes happen to think that two different Lumen levels appear to be the same, as long as we can avoid stepping on our pet armadillo in our back yard, at night

So - our comparison should certainly test LED intensity from two drive signals 'chopped' at the same periods; and then we want to compare the intensity with, and without accompanying storage

The previous tests were close to what we wanted, but not quite there - due to the initial voltage of 4.5V on the supply cap, the LED was initially bypassing the pulse operation for both test setups (hence the odd 'double-peak' start to the intensity profile);  only after this initial current surge for both test conditions did the supply voltage discharge below the effective forward voltage for the LED at around 2.5V

Using an initial supply voltage just below 2.5V, i've been able to repeat the tests and still get sufficient intensity to provide useful photometric data - the peak level and the duration of illumination will both be reduced of course, so the final values for average intensity will be significantly less, too

The graphs below show the valid results for what we wanted to compare earlier - Conrad, i'm sure you'll be pleased to find that the you were correct in thinking that the average LED intensity of this 'storage' circuit is less than that for the grounded LED which just allows the output energy to deplete the supply directly

The peak intensity is still the same for both conditions, as i explained in the first attempt at this comparison

However, you may be surprised to find that the difference in average intensity between the two conditions is only 20% (average photometric intensity levels were 0.04 & 0.05, respectively, for the 'storage' and 'grounded' setups)

So the doubling of illumination runtime in this storage circuit cannot be anywhere near explained by a reduced illumination level

An interesting test, thank you Conrad

np



nul-points

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #41 on: January 25, 2016, 01:16:41 PM »
... my bat42 just arrived...

I made a pcb with the 2x bat42's, BC547, 10x 10F supercaps, 100K pot, 10mm led, 100uF buffercap.
The 10x 10F supercaps a divided 2x 5 in series making 2 stacks of 2F caps, backed/loaded by 2x 750mAH 1.2V rechargeables for now.

...

Where does the power come from powering the led?  Is it because its kind of floating compared to ground, so a measuring error?

Regards Itsu

...a few comments on points you raised (here or on the vid):

- the BAT42s will only make an improvement in the efficiency if the 1N58xx Schottkys were leaky
- the LED is clamped to the common line by the BAT42 at its anode, so there won't be a floating measurement type issue with the LED power reading (more likely, i guess is that you're not getting a good value for the supply power (may need a CSR inline with the input & get the scope to do math on that?)

timed measurements of a set voltage discharge from a (measured/calculated) i/p supercap should confirm i/p power nicely

Conrad, re. some of your suggestions above, i developed this circuit initially with a pulse motor towards the end of last year and have some results from that which i may be able to add here - also used the circuit just to feed back to the supply;

the question is not, i believe, what happened to the extra energy, in the case of the grounded LED (that circuit arrangement just feeds the current straight back into the supply where it depletes the source 'charge' (aka 'gorge') on the i/p capacitor, as in conventional supply-circuit-load arrangements - no, the question should be 'how has the use of the input energy been extended?', and i believe that the answer is that the energy is still in 'transit', as it were, on the way back to the supply, but has been diverted into temporary storage before being re-used for more work on the return journey


hope this helps address some points raised - thanks all
np

conradelektro

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #42 on: January 25, 2016, 06:42:44 PM »
Today I saw three different LED-flash-lights in a local shop.

The prices are in Euro and all had the three batteries (3 times 1.5 V AA, or 1.5 V AAA = 4.5 Volt supply, the two round lights in a package had 6 x 1,5 V AAA = 2 times 4.5 V) included.

That seems to be the market to compete with. And without batteries one gets these LED flash-lights even cheaper. It seems that "brightness" is the desired goal, not so much "run time". Of course one would like both, but to increase "run time" one has chosen LEDs with higher light output (per Watt) and not a more complicated circuit.

Greetings, Conrad

nul-points

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #43 on: January 25, 2016, 10:58:47 PM »
...
That seems to be the market to compete with. And without batteries one gets these LED flash-lights even cheaper. It seems that "brightness" is the desired goal, not so much "run time". Of course one would like both, but to increase "run time" one has chosen LEDs with higher light output (per Watt) and not a more complicated circuit.
...

That's certainly a good representation of the current market - both for the flashlight itself, and the cells (usually primary, eg alkaline)

I see a niche market for something a bit smarter than just a plain flashlight, though - i think people would be willing to pay more for a device which is rechargeable (say solar + micro USB?), has a control to optimise either intensity or duration, is efficient ...and can be used to recharge a variety of portable devices  eg. phones/tablets etc,  via a standard USB outlet

C'mon, Conrad, even you would pay 30 Euros for a tool like that!  ;-)

All the best
np

PS  i'm currently using one of those circular 24 LED units above as my LED head - works well with 2 or 3 AAA cells - today i used it with 3 cells i/p to recharge the 9V NiMH for my DVM (obviously the flashlight had energy left afterwards, i was just using its capability to charge an output battery which is 2-3x the i/p battery voltage)




TinselKoala

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Re: "...that's not a knife - THIS is a knife!!!" ...er, OU flashlight
« Reply #44 on: January 26, 2016, 05:49:42 AM »
Quote
The simplest way of driving a LED pretty efficiently: use three AA batteries in series (they will start out at 4.5 Volt and run down slowly to 3 Volt in 90% of their run time), choose a resistor in series with the LED, so that the LED has its nominal current at 4.5 Volt. It is hard to beat that very simple circuit in terms of run time and light output per energy input.

Greetings, Conrad

Actually... the series resistor has two faults: First, it dissipates power itself, and second, as the supply voltage changes, the current through the LED and resistor changes, hence the brightness of the LED changes.

It is actually "simpler" (for some values of simpler) and more efficient to use a linear current sink instead of the resistor. The AP2502 that I have been playing with for some time is such a device. This 4-channel linear device is more efficient than a series resistor and keeps a constant current of 20 mA (or 40 or 60 or 80 mA) through an LED as long as the supply voltage is over the LED's forward voltage. It even works well with pulsed JT type circuits. It has an "Enable" pin that can be used with the usual PWM scheme to vary LED brightness consistently. The advantages are that it does not waste power the way a resistor does, and it keeps the current (and hence the LED brightness) constant as the power supply voltage varies. The disadvantage is that it comes in a SOT-23-6 package!

http://www.youtube.com/watch?v=X9wxuRZV-Ro

In terms of LED efficiency (lumens per watt of electrical power) it is hard to beat the Philips LumiLEDs. See the data sheet below: