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Author Topic: Lasersaber strikes again. A joule thief king ?  (Read 377697 times)

Offline conradelektro

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Re: Lasesaber strikes again. A joule thief king ?
« Reply #105 on: May 18, 2014, 12:05:26 PM »
Has any one tried the Touchstone TS3002 chip with their demo board yet?  This has an amp draw of less than 1 micro amp.  I happen to have one of these demo boards and will dig it out and see what happens.  I also have about 6 spare chips for it.

This should be able to drive an led for a very, very long time.

Bill

The TS3002 is difficult to get and very difficult to handle (so small). If one reads the data sheet it becomes clear that in any useful application its power draw is a few µA (4 µA, not only 1 µA).

One would need a breakout board like this: http://uk.rs-online.com/web/p/clock-timer-development-kits/7877201/ (very expensive)

I think that the TLV2401 (used as an astable multivibrator, http://at.mouser.com/Search/Refine.aspx?Keyword=TLV2401IPE4) is best, also because it is available in a practical TIP T8 package.

With the TS3002 or the TLV2401 one needs an additional transistor to drive a coil (back EMF drives LED). With the TS3002 one could get away with only one battery, which would be nice. May be there will be a cheaper TS3002 breakout board available or a 1 Volt OpAmp.

It is not easy to work at 1 µA and 1 Volt. That is the reason why LaserSaber uses the 9 V power source (9 times more Wattage, 9 V and 1 µA --> 9 µW, 1 V and 1 µA --> 1 µW).

If one uses any integrated component, it is hard to beat what I did at (with very careful design one could maybe get at half the power draw, 15µW to 20µW)
http://www.overunity.com/14591/lasesaber-strikes-again-a-joule-thief-king/msg402574/#msg402574
http://www.overunity.com/14591/lasesaber-strikes-again-a-joule-thief-king/msg402695/#msg402695

Greetings, Conrad

P.S.: I do not want to diminish LaserSabers great work, I juts look at the numbers. A big advantage of his approach are the few components, the drawback is the special coil and the difficult transistor choice. But at 1µA any component is a difficult choice, even today.

Offline d3x0r

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Re: Lasesaber strikes again. A joule thief king ?
« Reply #106 on: May 18, 2014, 12:07:28 PM »

replication of laser saber's latest...

http://www.overunity.com/14524/3v-ou-flashlight/msg402895/#msg402895


mpsa16 isn't so unusual of a transistor...

Offline conradelektro

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Re: Lasesaber strikes again. A joule thief king ?
« Reply #107 on: May 18, 2014, 12:17:20 PM »
replication of laser saber's latest...

http://www.overunity.com/14524/3v-ou-flashlight/msg402895/#msg402895


mpsa16 isn't so unusual of a transistor...

Interesting.

Using a modern integrated component is of course the bland and boring thing, no hope for OU. But it would be transparent and easy to replicate. I just wanted to see how well the MAX931 circuit compares and if I could make it work at all (if the concept was right).

Naturally, the more interesting and exciting thing is what LaserSaber (and his bona fide replicators) are doing. One can even hope to suck electrons from somewhere (ground, static electricity in the air, ...).

Getting the MPSA16 (or NTE47) from standard channels is not possible, you have to go to sellers who specialise in outdated componets and how long will that work? But I think one can find a modern equivalent given the expertise and determination. I guesse one can work with a small cap at the base of the transistor to make the pulse shorter.

Greetings, Conrad

Offline d3x0r

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Re: Lasesaber strikes again. A joule thief king ?
« Reply #108 on: May 18, 2014, 12:54:43 PM »
Interesting.

Using a modern integrated component is of course the bland and boring thing, no hope for OU. But it would be transparent and easy to replicate. I just wanted to see how well the MAX931 circuit compares and if I could make it work at all (if the concept was right).

Naturally, the more interesting and exciting thing is what LaserSaber (and his bona fide replicators) are doing. One can even hope to suck electrons from somewhere (ground, static electricity in the air, ...).

Getting the MPSA16 (or NTE47) from standard channels is not possible, you have to go to sellers who specialise in outdated componets and how long will that work? But I think one can find a modern equivalent given the expertise and determination. I guesse one can work with a small cap at the base of the transistor to make the pulse shorter.

Greetings, Conrad
I ran down to frys and picked up some NTE47's...
radio shack has them...


oops it's MPSA18 ; jameco...


not so esoteric...




Offline TinselKoala

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Re: Lasesaber strikes again. A joule thief king ?
« Reply #109 on: May 18, 2014, 03:09:12 PM »
I'm afraid I don't trust these tiny current readings done by conventional DMMs, in circuits involving capacitors and pulsing outputs.

Here's an idea I'm experimenting with: calculate the average current by monitoring the voltage drop on the capacitor over a known time interval.

That is.... you have your reservoir cap, in my case the 10F supercap in the TKBloomer circuit. You charge it to a precise known voltage, say 2.000 volts, and with _no load_ you see what its voltage is after 10 minutes. Say it's 1.998 V. Now you can compute the open-circuit leakage current of the capacitor, from knowing the change in voltage, the capacitance, and the time interval. Now recharge to 2.000 volts and turn on the load. After 10 minutes, look at the voltage on the capacitor. Say it's 1.500 volts. Now you can compute the _total average current_ delivered by the cap over the ten minutes, and subtract the leakage current determined earlier, and you will have the average current drawn by the load during your time interval.

I think this process may be more reliable than using the DMMs to measure microAmp currents.

ETA: On the other hand, since the electrolytic caps have the "recharge" phenomenon, as I've illustrated in the TKBloomer video ... they can even light the LEDs when their voltage is _rising_, so maybe using the voltage on the cap isn't such a viable idea after all. I'll have to run some tests....

Offline TinselKoala

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Re: Lasesaber strikes again. A joule thief king ?
« Reply #110 on: May 18, 2014, 03:11:46 PM »
http://www.ebay.com/itm/3-x-MPSA18-NPN-General-Purpose-Transistor-Free-Shipping-/261092142922

Three for a US dollar, delivered to your mailbox anywhere in the world.

In my testing I have compared MPSA18A and BC337-25 (as well as many other NPNs). (I had to buy a lot of 50 of the BC337s to get a reasonable price like a dime apiece.)
The two are very close competitors; in some JTs one works "better" and in other JTs the other one works better. My criteria for "better" include both low operation voltage and LED brightness. Also... be sure to scope your circuit _after the LED goes out_ to see if the thing is still oscillating.  I recommend using a socket for the transistor so you can easily compare types and individuals within a particular type (they do vary). Also try the transistors "backwards" with C and E reversed in the circuit... you may be surprised.

Offline Vortex1

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #111 on: May 18, 2014, 08:14:13 PM »
Hi Conrad:
Here is a simple circuit I've been playing with on the bench. I went through about 6 different types of simple LED pulser circuits using FET's, SCR's PUT's etc and liked this one for it's simplicity, a single inductor, regenerative latch, timing cap and resistor. Attached is the basic design with no component values, as each version can be tailored for the voltage, duty cycle, and light output amplitude required.

I have souped up lower current versions which I will post later, this is just the basic circuit to play with. This one does not have the advantage that a blocking oscillator has i.e. high current base drive at little expense to the power drain, also it is not in the class of uWatt long runners, but will work down to 1 volt so can be operated off a single 1.5 V battery cell.

P.S. Yes, put a current limiting resistor in series with R1. This is a rudimentary circuit to give the concept and not a production schematic.

Offline Vortex1

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #112 on: May 18, 2014, 08:27:56 PM »
Here are some numbers you can use to qualify your designs.
They are continuous mode operation rather than pulse mode.

Also these tests are far below the actual Lumens the LED's are capable of, I'm just measuring at the threshold or lower subjective level of light since no one seems to be quantifying and integrating actual light power delivered vs. power usage.

A single bright white LED (old one I had laying around):

3 uA       3V        0.009 mW           Just Visible
10uA      3.3V      0.033 mW           Definitely Visible
100 uA   3.8V      0.38 mW             Bright
1000uA  4.12V     4.12 mW             Very Bright

A cluster LED array like Tinmans latest video:

2uA        3.27V     0.0065mW          Just Visible
10uA      3.42V     0.0342mW          Definitely Visible
100uA    3.53V     0.353mW            Bright but not evenly lit
1000uA  3.69V     3.69mW            Very Bright and fairly even distribution

You can calculate the energy in a 1000 uF  or 3300 uF capacitor charged to a given voltage and divide it by the required power
to see if you are exceeding expected run time and tapping any unknown source.

The problem is that in pulse mode e.g with a duty cycle of 10% on time a LED operated at 100 uA peak will look bright yet only be drawing 10uA average so this must be factored in when computing run times.

I have already done the calculations and run times seem to be right in the same order of magnitude that people are getting e.g. Lasersaber.

E=1/2CV^2

Let's apply a little simple math and see if anything unusual is happening.

I'm going to rerun these numbers using pulse mode, 10% duty cycle.

Maybe someone else can run the numbers also.

Offline conradelektro

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #113 on: May 19, 2014, 12:02:27 AM »
Here is a simple circuit I've been playing with on the bench. I went through about 6 different types of simple LED pulser circuits using FET's, SCR's PUT's etc and liked this one for it's simplicity, a single inductor, regenerative latch, timing cap and resistor. Attached is the basic design with no component values, as each version can be tailored for the voltage, duty cycle, and light output amplitude required.

@Vortex1: Interesting circuit, the art of multivibrators from the 1970ies. With modern transistors a very low power draw might be possible.

Can the duty cycle be adjusted with a diode and a second lower resistor in parallel to R1? The losses through R1 / C1 (frequency) seem to be the same as in the MAX931 astable multivibrator circuit? The wave form will not be a steep square wave, which will reduce the back EMF in the coil?

If your goal isn't chasing the lowest power still visible LED but to have a useful long lasting light powered by one or a couple of AAA cells then there are some very good options out there.   I think that 10 lumens is kind of the low end of useful light.  With the right LED you can get that on 80mW to the LED and a little more than 100mW drawn from the batteries.  A pair of AAA batteries gets you more or less 2Wh.  So you could go for 200 hours on such a circuit.

I looked at the "TPS61097A Low Input Voltage Synchronous Boost Converter With Low Quiescent Current". It allows to boost 0.9 Volt to 3.3 Volt (just right for a LED). But the losses at 0.9 Volt input are high (65% efficiency, and limitation to 50 mA output). But at 1.5 V to 3 V input (2 batteries in series which can run down quite low) the efficiency is 80% to 90%. With a 3 lumen Super Flux white LED (30 mA, two could be used to get 6 lumen light from 60 mA, three to get about 9 lumen from 90 mA) one could build a conventional LED driver to drive the LEDs continuously at nominal brightness from two batteries in series. Rechargeable batteries (which work at 1.2 V each) could be used as well.

http://at.mouser.com/Search/Refine.aspx?Keyword=TPS61097A (with 1.5 V to 3 V input only 90 mA at 3.3 V output are possible)

http://at.mouser.com/Search/Refine.aspx?Keyword=T4C4PRB (there might be better LEDs, but these have a low price)

Greetings, Conrad

Offline Vortex1

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #114 on: May 19, 2014, 12:40:39 AM »
Hi Conrad

The circuit I posted was later tried down to 1 Volt and worked well. The duty cycle increases at lower voltage to about 30%.

Besides actual testing on the bench I have also simulated the circuit in LTSpice if anyone is interested.

If one designing for lowest cost for a consumer torch to operate on a single 1.5 volt cell, the parts cost on this one will be hard to beat. A blocking oscillator using a tapped inductor might beat it, but transistors are generally a lot less expensive than coupled inductors.

As I said there are many improvements that can be made, as this circuit is elementary. The art is in making it tick better and at lower power drain. That's for later posts. Once the operation is fully grasped improvements come easy e.g. super beta transistors, speedup network etc.

Offline Pirate88179

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Re: Lasesaber strikes again. A joule thief king ?
« Reply #115 on: May 19, 2014, 12:58:54 AM »
The TS3002 is difficult to get and very difficult to handle (so small). If one reads the data sheet it becomes clear that in any useful application its power draw is a few µA (4 µA, not only 1 µA).

One would need a breakout board like this: http://uk.rs-online.com/web/p/clock-timer-development-kits/7877201/ (very expensive)

I think that the TLV2401 (used as an astable multivibrator, http://at.mouser.com/Search/Refine.aspx?Keyword=TLV2401IPE4) is best, also because it is available in a practical TIP T8 package.

With the TS3002 or the TLV2401 one needs an additional transistor to drive a coil (back EMF drives LED). With the TS3002 one could get away with only one battery, which would be nice. May be there will be a cheaper TS3002 breakout board available or a 1 Volt OpAmp.

It is not easy to work at 1 µA and 1 Volt. That is the reason why LaserSaber uses the 9 V power source (9 times more Wattage, 9 V and 1 µA --> 9 µW, 1 V and 1 µA --> 1 µW).

If one uses any integrated component, it is hard to beat what I did at (with very careful design one could maybe get at half the power draw, 15µW to 20µW)
http://www.overunity.com/14591/lasesaber-strikes-again-a-joule-thief-king/msg402574/#msg402574
http://www.overunity.com/14591/lasesaber-strikes-again-a-joule-thief-king/msg402695/#msg402695

Greetings, Conrad

P.S.: I do not want to diminish LaserSabers great work, I juts look at the numbers. A big advantage of his approach are the few components, the drawback is the special coil and the difficult transistor choice. But at 1µA any component is a difficult choice, even today.

Well, I got lucky and listened to Gadgetmall when he told us about this chip and the demo board on the other JT topic.  I asked for, and received the demo board and about 6 chips to play with...for free!  I actually had forgotten that I had it and dug it out the other day.  I just found the pdf online which explains how it works so, when I get a chance, I will hook it up and see what happens.  You are right, those chips are very, very small.  I am glad one was already installed on the demo board as I am not sure that I could solder one on there correctly.

Bill

Offline conradelektro

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #116 on: May 19, 2014, 03:53:05 PM »
Strange switching in LaserSaber's low power circuit with a 2N1304:

(This is not criticism, just some measurements.)

I got some germanium 2N1304 transistors and replicated LaserSabers circuit, only the coil and the two red LEDs are different (see the attached circuit diagram).

The circuit makes the LEDs glow for about 6 minutes with a 1000 µF electrolytic capacitor started at 9 Volt. It works better with two LEDs and the LEDs have to point in the direction given by LaserSaber.

Please see the scope shots for the strange switching going on. The base goes below the emitter (never above) and causes nevertheless a very short pulse.

For comparison I put a diode (1N4148) between base and negative rail to see "normal" switching, which makes the LEDs shine brighter and causes much more power drain because the pulse is much longer.

I think this clarifies why it does only work with certain transistors like the 2N1304 (and may be the MPSA18, not yet here) which also switch very shortly when the base goes below the emitter.

Greetings, Conrad

Offline conradelektro

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #117 on: May 19, 2014, 06:23:33 PM »
Did some more tests. LaserSaber added three feed back diodes to his circuit, and they seem to help a bit. I could extend the run time of my replication by about 20%.

My electrolytic capacitors are very leaky, where do I get ceramic caps with 1000µF or more?

Greetings, Conrad

P.S.: Just did a 30 minute run from a 4700 µF cap starting with 9 Volt.

7 minutes from 1000 µF should be about 33 minutes from 4700 µF, the 3 minutes loss were probably leakage. So, it is no fluke, the thing runs consistently (although the switching is peculiar). Will work on the coil in the next days.

Offline hotrod34

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #118 on: May 19, 2014, 07:34:29 PM »
Hi all,

Here is a question from a newbie. Have anyone tried some of Linear Technologys energy harvesting step-up converters
for example, LTC3108 ? It operates from Inputs of 20mV. Maybe we can combine it with a Joule thief and make something useful.

Regards,
hotrod34

Offline Paul-R

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Re: Lasersaber strikes again. A joule thief king ?
« Reply #119 on: May 19, 2014, 07:39:21 PM »
This is an inspiring and impressive project but how can we set out to scale the business up so that there are inputs and outputs that are more readily measured?