Hand-cranked dynamo alternative to Shutter Precision SV-9 for LED lighting system

 Julian Edgar's excellent article "Dynamo bicycle LED lighting system" got me very interested in the November issue of EPE magazine just out:

I want to try my hand at this.  BUT MINUS THE BIKE.

So can anyone suggest a small dynamo with the same specifications to substitute for the Shutter Precision SV-9 hub dynamo or the smaller, cheaper "bike bottle dynamo" in the set-up described by Julian in the article

What I'm looking for is most probably though not certainly a hand-cranked affair.

Michelle O'Brien
SE London

Hi Michelle-If you're doing this without the bike, you probably don't need a dynamo specially made to go in a bike wheel hub. FYI- any permanent-magnet brush-type DC motor will make a fine dynamo. Also, small stepping motors will generate a lot of power, but if you're looking for a DC output you will need to add rectifier diodes to each of the coil windings.What will you be using to turn the dynamo? How much voltage and current do you need? -Rick

Hello Rick
Thanks for your interest.Rectified  from AC to DC and smoothed, the dynamo's output will be fed into a small DC/DC buck-boost module that can output from 1.25 - 35V.

Julian says in his article that this requires a supply voltage anywhere from about 3 - 32V. And he adds: "A realistic input current maximum is 1A" for the intended LED lighting system.

All the details are given in his stuff in the  November issue of Everyday Practical Electronics magazine.

Hand cranking will most likely be my means to turn the dynamo but steam power might also be a possibility.Michelle

If I were you I think I'd start with a stepper motor.  Either cannibalize one out of an old printer or buy an inexpensive NEMA 17 motor on eBay. Look for a bipolar motor with 4 wires. These will have two windings with two wires each. Use an ohmmeter to determine which wires go to each winding.  Then connect the AC side of two  bridge rectifiers to the wires coming from each winding. For the highest efficiency, use Schottky rectifiers, like SP260TA in the bridges (most any silicon rectifiers will do, though).  Connect the positive sides of both bridges together.  That will be your positive output. Connect the negative side of both bridges together for the negative output. Spin the motor with your fingers and you should see some voltage come out.If you're going to hand-crank it, you'll need to add a couple of gears to increase the speed of the motor. Alternatively, you could use belts and pulleys, or even sprocket gears and a sprocket chain. I would think you'll need maybe  a 4X to 10X speed increase.-Rick  

Hi Michelle.  I love the idea of a steam-driven electricity generator...   Suggestion - you get hand-cranked torches that you could maybe take apart, though I don't think you'd get an amp out of them.  Also, you'll probably have to use some gearing, most motors are designed for fairly high speeds and you'd have to get them up to near those speeds to generate a reasonable amount of power.  One of my suppliers coincidentally just offered a geared motor here, but it's very highly geared (around 300:1) and that would probably be too much.

Hi Michelle,
First, thanks for the nice compliments about the original article. As others have said, any DC motor run backwards as a generator will work, as will a stepper motor with appropriate rectification. But it depends what you want to run - and you haven't said that!It's actually fumy that you say that you want to run it 'without the bike' because today I was buying some parts to try to achieve that, such has been the success of the bike system. (I am looking at using a geared-up stepper motor.)I did a story for EPE on a hand-cranked LED torch some years ago - and that also might be worth a look. Finally, the Shutter Precision generator is pretty impressive, so you might not so easily achieve the same output from something else. On the bike the drag feels like zero (it's not, but...).
Julian Edgar

You might be able to get a small sterling engine from Ebay and hook it to a small d.c. motor?  This could become very steam-punky!