DC generator

[Clouddancer]

Can anyone make suggestions where to find small DC generators or DC motors and small clockwork gearing parts? Would like to build my own no battery lamp that would run much longer than Freeplay's with either spring power or capacitors.

 

[Hemingray]

I had sent this in response to an e-mail inquiry, thought I'd also post it here...

I'd look in any electronic surplus or junk shops, check out places like All Electronics, Jameco, Hosfelt, look in any electronic hobby magazines, etc. Hobby and model making shops will have these, but the prices will be higher, Unless they sell surplus.
A "gearhead" motor is the easiest, as it incorporates the speed "step-up" all in one unit, but you don't want too great a gear ratio, else the effort
To turn the motor may be too much, or it may not turn at all. Something like 10-20 to 1 (going from output shaft to motor, (they are actually rated as 1:10, 1: 20 reductions). I've played around with this since I was a kid, way
Long ago, using various Erector Set / Mecanno Set parts and small "toy" DC motors. Another possible source would be smaller motors used for "robotics" Experiments, smaller and less powerful versions of the machinery used in "Robot Wars" and similar shows on cable TV. A permanent magnet DC motor (the most common small and inexpensive type) will generate DC, polarity is dependent on direction of rotation. A "stepper" motor if it has a permanent magnet rotor, will generate multi phase AC, which can me rectified and turned into DC, with no directional polarity differences. Steppers can be found in old 5" floppy drives, old magtape drives, and the like. Small DC Motors can be salvaged from toys, CD and floppy drives, etc.

I've taken a couple of the cheap made in China (or Russia) "squeeze generator" flashlights - sometimes called "Forever Lights" and converted them to LED, these generate AC, so I added a DIP size full wave bridge rectifier and a "supercap", and changed from incandescent bulb to a home made 3 -LED "bulb" that screws into the original socket. These are always good for an emergency, as no batteries are involved.

If one is lighting white LEDs, the power needed is about 60 to 80 milliwatts Per LED. So three, would be approximately 200 mW (1/5 watt). Just for comparison, one HP is equivalent to about 750 Watts, more like 1000 watts in the real world, accounting for various inefficiencies.

--Edward W. Brown

 

[Marked]

http://www.sidewindercharger.com/

http://www.scientificsonline.com/
http://www.scientificsonline.com/ec/Products/Display.cfm?categoryid=192964

 

[Clouddancer]

Hemingray and Marked, thanks very much. Excellent and very useful. Going to save this page for reference. The Edmund Scientific links show some very interesting possibilities such as running their high torque motor/gearboxes backward. Now to find the long run spring to with it. I ran across at least one Chinese company during a search that makes the coiled constant force type, one of which Freeplay uses.
Hemingray your info will be very helpful in making it practical.

Another question for you guys: It sounds to me like you could use one of these miniature motor & gearboxes to charge up large capcitors and use them to release regulated power. On the other hand using a large coiled spring geared right to slow it down and run a DC motor to a regulator sounds like it would do the same thing. However what's your opinion of which would likely result in the longer run time and which do you think might result in the least amount of cranking versus run time? I'm guessing with spring powered you would still need to use capacitors but geared right the spring might keep them charged up longer than direct hand cranked charging.

No doubt if I can produce the right power you guys can suggest LED arrays that will burn holes in the wall.

 

[**DONOTDELETE**]

here's another, an Alladin foot operated one -- "coming soon" --
http://www.aladdinpower.com/steppage.htm

 

[B@rt]

CD, the 2020 has more spare room than the Coleman, but because the spring mechanism takes up quite some space, actual "modding" room might be restricted...

There should be ample room for improvements though.

 

[Clouddancer]

So what about the question above, Bart, Hemingray? It sounds like you guys are already familiar with the 2020. Would you suggest modding the 2020 with supercaps for longer run time or would that accomplish anything without a more powerful spring? Any other suggestions for longer run time using only the generator?

 

[LoneRebel]

Clouddancer, it sounds like the energy is stored in the spring meaning that it uses that stored potential energy and converts it at a constant rate into electrical energy in escence the spring *IS* the battery. You could put super caps in but I dont really see much of a point because if you did put the caps in, it would still charge the cap as the spring uncoils. The whole process of releasing the stored potential energy takes place in about 8 minutes(8 mins runtime). The light also has a NiMh battery in it which sounds as if its separate from the crank. This powers a more powerful xenon bulb. What I think would make a nice mod would be to replace that with a nice luxeon side emitter. I'm not sure what the battery configuration is on that light as the specs dont come up but I'd imagine that it is at least 2 NiMh's. A orange luxeon side emitter is still relatively bright at that voltage with 2 NiMh's.

Anyways, that is my take on the subject. Hope it helps

 

[Clouddancer]

LoneRebel -so using the batteries a luxeon side emitter would give more light than the xneon? Why orange?

I was thinking of supercaps to store power because I might be able to find a suitable more powerful constant force spring replacement. I'm new to this but from what I've been seeing on the forum I'm guessing that's the way to extend the run time with just the spring because the 2020's spring already powers LEDs. No doubt with some help I can improve on the LEDs but first I want to improve run time. What do you think?

 

[LoneRebel]

Cloud, since the xenon is an incandescent I'd imagine that it would draw significantly more current than a luxeon thus increasing the runtime plus they never burn out. The amber/orange luxeon star side emitter is one of the few luxeons that does well at low voltages. If the light uses 3 or more cells, then use any color of luxeon.

Replacing the spring sounds like a good idea, but I'd imagine that they probably put in the largest spring for the available space in the light(just a guess).

 

[B@rt]

CD, I don't have the 2020, I'm judging from the pic...

A MicroPuck should be able to drive a Luxeon nicely.

I'm not sure about modding the generator itself, maybe replace the NiCd cells with cells that don't have a memory effect?

Since it is no problem to rewind the generator while in use, I'm not too sure what replacing the spring would accomplish, other than a few more minutes light on one wind...

 

[PsycoBob[Q2]]

NiCd's DON'T have a memory effect. They DO have 'Voltage Depression Induced by Overcharging' effect.

NiMH might be better, just for energy-density concerns. Or you could use a 3.6v Li-ion meant for electric plane models. Built-in protection circuitry, light weight, and decent cost... plus bragging rights. Micropuck and Li-ion would work, apparently.

I might make one of these spring-powered lights my next flashlight purchase, if I can find one that can be modded to charge 2AA's for use in other stuff. I saw one locally that had a 12v output at 300mA, for running cell-hone chargers and some low-current battery-chargers.

 

[Tomas]

Right on, PsycoBob!

Memory Effect

==x==

 

[Clouddancer]

Just ordered a Freeplay 2020 (spring powered/LED/rechargeable) from Cheap Sales Mall Freeplay 2020 for only $45. Looks like it has more room in the body for modifications and easier to carry than the Coleman. When it comes in I'll get you guys to help me tweak it. Ha, light saber here we come! The mothership will be pleased.

 

[B@rt]

I stand corrected!

Tomas: Thanks for the interesting link .

Bob: Is this something simular?

Motorola Freecharge



btw, someone mentioned (in another thread) that replacing the 2020 with the Sherpa was a step backwards, but, the KISS principle offers greater reliability, and since Trevor Bayliss' first goal was to provide cheap and reliable tools, this is just an evolutionary step.

 

[Clouddancer]

Thanks guys, that is all very helpful. I agree Tomas, very informative link. And thanks for the Micropuck link Bart.

I think you're right about replacing the spring. I've been looking at constant force spring designs in manufacturer catalogs. The two large black discs you see through the case, one with the crank handle, apparently house the two ends of the spring, relaxed or wound. So there's no room to enlarge it and my guess is that the only improvement you could make is with a more powerful spring but the same size. From the looks of the manufacturer's products evidently possible but maybe not worth the trouble. My guess is that it doesn't take eight minutes to unwind put charges a capacitor that will take that long to discharge to the LED draw. If so then perhaps the only pratical improvement might be better LED's but not run time for the spring power.

Now I'm wondering if you abandoned the spring entirely and used manual crank of the generator directly through a regulator to charge supercaps whether you might have a viable path to improved no battery run time? Maybe power 5W Luxeons that way? No doubt there's a good reason why Freeplay didn't do this. Anyone have a guess?

Improving on the xenon bulb setup with a Micropuck (or Bad Boy from the sound of it on the Manf Ann-Micropuck discussion -interesting) and a side emitter sounds very good.
Where do you find Luxeon side emitters and
Li-ions? Li-ions at model airplane shops? Why bragging rights on Li-ions? Just more sophisticated or lighter than Ni-MHs? I take it they don't store as much enegry ("energy-density"?) as Ni-MHs right?

 

[LoneRebel]

Cloud, Supercaps are expensive and are nowhere near the capacity of regular rechargable batteries. The reason why the capacitors work in powering an LED is that regular LED's(non luxeons) need very little power. A single LED will work at around 3.6v @ 20 milliamps. And of course LED's get more efficient as the voltage drops. A luxeon 5W LED is 7.2v@700 milliamps. You'd have one huge and extremely expensive flashlight if you used supercaps to power a 5W for any length of time.

 

[Clouddancer]

Ah-ha, I see. Thanks Lonerebel. Oh well, I guess I'm still ahead with a Freeplay instead of a shakelight because it also carries batteries that it can charge itself. I wonder which puts out more light?

 

[Clouddancer]

Got my Freeplay 2020 today. Well, hmm. It has three white LEDs running directly from the spring powered generator, as best I can tell without a capacitor. The light output from them is pretty wimpy and they are soldered in so they can't easily be changed. The light is actually pale blue not white. But they would be better than nothing as a last resort in a long power outage. Through the clear case it's kind of cool watching how the mechanics work. The reflector surface is nibbed rather than smooth evidently meant to scatter the light for some reason. The light output from the single xenon bulb running off the NiMH pack is pretty good but 45 minutes run time sounds like a lot less than I recall most modders are getting with evidently equivalent light output. The xenon is replaceable so I'm wondering if there's an LED that would put out equal light with slower power consumption. Any suggestions?The NiMHs charge on 6 volts so it can't be rigged to charge from an automobile. All things considered though I guess it's not a bad little rechargeable for the price. I also got to try a shakelight today in Brookstone's. Quite impressive actually, for a single LED. It actually appeared to have better output than the three in the Freeplay by using a good reflector and a magnifying focusing lens that works very well. Hmm.

 

[LoneRebel]

Clouddancer, in the case of you wanting to charge your freeplay 2020 with a car adapter it is usually not much of a problem. Voltage regulators can drop the voltage and dissipate the excess power as heat or you can use resistors. Anyways what you need is something like this www.cetsolar.com/caradapter.htm . I did a search for '6v car adapter' on google and that is the first site that came up.

Sorry to hear that the LED's arent that bright. I'd be interested to know how much voltage and current are going to those guys. Anyways, a thread was started about the coleman sentinel flashlight which is a freeplay crank driven flashlight. It has a bulb in it that operates in one of two modes 140ma or something like 1.2 amps. 30 seconds of cranking supposedly makes the light shine for around 8 mins. 140 ma is enough to run 7 super bright LED's. It doesnt use a spring and stores its energy in 3 AA 1000mah NiMh's. Anyways, I broke down and ordered one. Its not clear like your freeplay 2020 but it sounds like it'll be a modders dream🙂