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Needing simple solution to get a toy steam engine dynamo to power a USB port

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kevin Graber

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I will admit from the git-go that i am almost totally electronically illiterate. So please factor that into any responce.

Here is what i am trying to accomplish. I would like to use a toy steam engine dynamo to power a USB port for the purpose of charging phones etc.
Here is a link to a comparable dynamo i would use
http://www.ebay.com/itm/Model-Steam...887752?hash=item3ac091dc48:g:AekAAOSwLpdW~Sm8

i would like a simple device that can purchased as a unit from some electronics supplier like www.linear.com as opposed to building such a thing from scratch. However i realize there may not be any such a component or that slight modification would be needed to existing component, but i am striving for the most simplistic approach.

Standard USB ports output 5 volts and most phones need a minimum of 500 mA so i am looking for some type of regulator that will take fluctuating voltage and cut it off completly if it drop below 5 volts and cap it off if it rises above 5 volts. also it would need some sort of resistor valve (for lack of better term) that would keep the battery from draining back into the dynamo.

I will be happy to provide some financial compensation for a solution as this will be used in commercial application and i will possibly be looking for to pay for some advice in the future as the project develops.

Thanks
 

Diver300

Well-Known Member
Most Helpful Member
A diode is what you want to stop current flowing back. However, USB loads usually do that themselves. Also, USB loads won't be damaged by lower voltages, so there isn't really a need to cut off at low voltages.

Manufacturers like Linear won't supply individuals, but Maplin, RS, Farnell, Mouser and Digikey, to mention a few, have websites to let you buy online.

A simple linear regulator (https://en.wikipedia.org/wiki/Linear_regulator) is probably what you want. I suggest a low-drop out regulator. The drop-out is the minimum voltage difference between the input and the output, so you want that to be small. You don't want to have to generate 7.5 V or so all the time to reach 5 V on the output.
 

awesomelumens

New Member
There is a product ltm4623 on linear.com .. it can be set for this project. But if you really need only 500mA than go for lm7805. Its much simpler :D
And that valve is perhaps a diode. :D
 

awesomelumens

New Member
Explaining a little bit: a linear voltage regulator dissipates the excessive voltage as heat. So here lm7805 if given 12 volts will dissipate 3.5watts as heat and give you fine 5V at 500mA. Usually mobilephones wont stick to it and would go above this value. The motor in link is giving 12 volts. It would obviously fluctuate with steam. You might be getting 8V or 16V. Lm7805 can manage between 7.5 to 40. You can place a zener of 8 volts before ic. So now if voltage goes down it would be stopped. On the other hand place a zener of 15volts to a brake circuit if you cant control steam much. I think mobiles with OTG can provide current to a motor. But with these semiconductors etc lying there it wont be a concern.Actually its quite similar to windmill project of college I suppose
 

Dr_Doggy

Well-Known Member
a good buck converter is a much better choice, it can have wide range input and solid 5v output, more importantly it is more conservative of energy and does not waste it all as heat
 

tcmtech

Banned
Most Helpful Member
I would just use a car charger adapter being the ones rated for 24 volt vehicle systems will take 30+ volt DC input without problems.
 
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