Lasersaber strikes again. A joule thief king ?

[MileHigh]

I looked at Lasersaber's rechargeable flashlight, it's really nice.  It's much nicer than those cheap "shaker" flashlights.  That really can bring a reading light to the Third Word.

I can envision a nice addition where you have an auxiliary capacitor bank that you connect to the flashlight so you could hand crank up a much larger capacitor.  Then you could read for a 45-minute stretch before having to crank, as an example.

It's the concept of a "DC house" for poorer countries.  You make it a modular concept.  A deluxe very large capacitor bank and an some kind of foot crank generator that could be cheaply and mass produced would be very interesting.  Then you could be energy self-sufficient for your lighting, have a radio or small low-powered LCD TV, laptop, wireless Internet, recharge your cell phone yourself, etc.

You would not have energy for cooking, but at least most of the other things we take for granted would be available in low-powered DC versions.  If you assume that 15 - 30 minutes worth of foot-cranking could accomplish this, then I think you are in pretty good territory to make the concept viable.

MileHigh

[conradelektro]

I can envision a nice addition where you have an auxiliary capacitor bank that you connect to the flashlight so you could hand crank up a much larger capacitor.  Then you could read for a 45-minute stretch before having to crank, as an example.

It's the concept of a "DC house" for poorer countries.  You make it a modular concept.  A deluxe very large capacitor bank and an some kind of foot crank generator that could be cheaply and mass produced would be very interesting.  Then you could be energy self-sufficient for your lighting, have a radio or small low-powered LCD TV, laptop, wireless Internet, recharge your cell phone yourself, etc.

MileHigh

Some numbers about a "foot crank generator":

http://spectrum.ieee.org/green-tech/conservation/these-exercise-machines-turn-your-sweat-into-electricity

An elite cyclist can produce more than 400 watts, more than half a horsepower, for an hour or more at a stretch. But the average person, even somebody in good shape, can generate only 50 to 150 watts during an hour of strenuous exercise. If you could capture that power to produce electricity, what would it be good for? Not much, really. It could power a television set for about an hour, which might keep you entertained while you pedaled away to produce the electricity in the first place.

My opinion:

With an "exercise bike type of generator" you can maybe generate 10 Watt hours before being pretty much exhausted. If you make a real effort for an hour, may be 40 Watt hours. This would give you a decent LED lamp which uses 2 Watt for 5 to 20 hours. Still, pretty useless and the bike would be bulky.

Two 100 Watt solar panels (which cost about EUR 125.-- each) would do much better even if you only have 4 hours of sun.

I think that EUR 1000.-- will buy a solar panel system including electronics and batteries which would cover real lighting and a laptop every day if you install it yourself in a straight forward manner. That means you will have two or three rooms with a 4 Watt LED lamp (at 12 Volt) and in one room the 220V / 300 Watt converter with a socket for the lap top. Alternatively to the laptop you could run a smaller TV set and whenever you want a radio or CD player.
The real problems are refrigerator, washing machine, dish washer and cooking, and you can forget heating or air conditioning.

What I want to do with my hand cranked stepper motor:

6 x 4700 µF 25V caps (which I bought some years ago very cheaply) can be filled to 15 Volt with about 10 turns of the crank, which would give 30 minutes light from the three white LEDs. This light allows to read when holding the book at 40 cm from the LEDs or it would be lighting enough not to fall over things in a room at night. The light is comparable to what Lasesaber shows with his 3d-printed blue flash light. I just tested it. I will use a Ferrite toroid instead of my nice big transformer core or will buy some of these little Ferrite pot cores if the toroid does not work well.

This is nothing fancy and the usefulness can be doubted. But I have the materials at hand, why not build it?

Greetings, Conrad

[Farmhand]

Yes he's done a nice job, well done. I have to say though hand cranked torches already exist,
there are cheap ones and better quality ones. some have a radio and a 5 volt output for
charging stuff. I've got some pump torches that work great, a couple of pumps and
two bright LED's go for quite some time.
I've also got a crank torch that has 5 x 10 mm LED's and it works well too.
Lights up those 5 x 10 mm LED's real good.

Second thing is. What exactly does his torch have to do with Tesla ? I don't get the relationship.

Surely to use Tesla's name the device must have some unique principal involved which is related to Tesla directly.

ie. My pump torches use an alternator to charge the little batteries, hence I could re-badge them and sell them
at "markup" as "Tesla Torches", if I was unscrupulous.

I have absolutely nothing against people making some money from stuff.
I am just curious how he justifies using Tesla's name to sell a crank torch.

..

With hand cranked stuff people would be amazed at the energy input by the person cranking for just one turn.

Last night I used a small circuit to light three LED's for about 5 minutes, powered from a 25 Farad capacitor
from between 1.25 volts and 0.8 volts, which works out to a consumption of about 11.5 Joules for the run.
The Three LED's had 9.2 volts across them at the beginning and about 8.8 volts across them at the end.

This is the type of info we should give.

The energy in the capacitors came from a single galvanic cell.
I charged them in parallel then used them in series, so it must be a Tesla based device as well. 

The circuit is still in prototype and is a long way from optimization point.

..

[Farmhand]

We should be asking Lasersaber, if he would kindly crank the setup for the three seconds,
then measure the voltage on the capacitor and tell us the capacitor's capacity.
Then show or tell how long it runs and the voltage across the LED's during the run.
( I trust him to just "tell" as he's been truthful with me, before when I asked a question )
Then we can see the efficiency of the device in operation.

I have a capacitor across my LED's so I can measure a stable voltage across them, which
is not that important if we know the stored energy and the run time, but it does help us
to know how bright they really are.

Reflective cones around the LED's should make for more efficient light output,
maybe he can design some reflective backings for his torch to improve it's light output,
if he hasn't already done that of course, he may have that covered already I could not tell.

..

[d3x0r]

@farmhand
I definitely agree with your disagreement with the choice of names   It's not even a circuit like the Kacher....


@general
I got some of these exact parts to try replicating with those.  There are many too many variables


Changing the cap to the aluminum electrolytic definatly made a difference... I have a 6800uF I was using, but that didn't last too long, got a 56mF 16V cap similar to laser sabers (same brand and style, different rating) and the signal on the base/collector looks entirely differently between the two


I've blown up a half dozen or so mpsa18's   one even arced and shot off a piece


I've seen so many modes of this working... from basically a continuous sine-wave (high power drain) to the occasional burst mode.  The last, a higher voltage mode, gives me a spike and then a double back spike similar to what akula was showing; I dunno on some low power circuit (v4?3?); and actually a higher voltage gets me multiple spontaneous spikes... not entirely sure what's causing those...


attached my circuit; it works most often and gives me the most light, but it's not as low current draw. 


A couple days ago I picked this up to play with some more while I considered how to fix my mazilli... but anyway, I had shared this with a EE friend, and after that I had the hardest time getting it to work even with the red LEDs I WAS playing with... I had swapped to blue, but they have a slower current draw, so the wave on them looks again entirely different.  (and the red look different from both the blue and these white I'm using).


Once I got a 10M resistor I was able to see more of the sporadic bursts similar to what was scoped by steven jones on laser saber's device.... at one time when I had that, I increase the voltage from 8.7 to 9.7 and the sporadic character went away in favor of a more continuous mode... it's actually very hard for me to stay in a band where it is a burst, space and another burst (even removing the extra cap and diode I added)


I thought about making a video, but there's so many variables.... it's definitely like balancing an egg on its end or something... if the exact conditions are right, it can be done.




(additional cap is 2.2nF ... pretty much anything larger than nothing helps... and too much kills it)