Bike power: version 2 – field test

Bike power complete. Bike, bike stand, 3 phase rectifier, capacitor,  6 Amp solar battery charge controller, 12V bulb.

Bike power complete. Bike, bike stand, 3 phase rectifier, capacitor, 6 Amp solar battery charge controller, 12V bulb.

The bike ( on a bike stand ) were attached to the 3 phase rectifier and the 1 Farad capacitor to produce 12V DC.

The wheel is a  200 W 36V wheel so the bike could only be operated at a low ( comfortable) speed to prevent too much voltage and too much current.

A 12V 50W dichroic light bulb was added to show it was really working.

capacitor at 13.6 Volts and 50Watt 12 Volt dichroic light working.

capacitor at 13.6 Volts and 50Watt 12 Volt dichroic light working.

PV charge controller added using the bike as the power input instead of the solar panel and battery charger was used.

Probably best for charging a small device unless you want to pedal the bike for a long time.

Future additions:

36 to 12 volt step down for a higher current lower voltage system.

replace the back tire with a smooth tread tire.

Degrees minutes and seconds: human time and distance scale

It helps to have a tangible reference point when talking about degrees minutes and seconds.

If you plan journey using degrees minutes and seconds these are the real world parameters.

1 degree of an arc is = 60 Nautical miles = 69 Statute miles = 111.12 Kilometers

About 4-5 days walking at a typical speed on roads.


1 minute of an arc = 1 nautical mile = 6076 feet = 1.15 statute miles  = 1.852 kilometers

About 20 minutes of time walking at a typical speed on roads.


1 second of an arc is therefore 101.2666 feet  = 101 + 4/15  feet =  101 feet 3.2 inches = 33.755 yards  = 30.866 meters

20 to 30 seconds of time walking.

The size of a large house.

I did try to compare this distance to a football/soccer field. but even that is not standardized, if the most widely played sport has no standardized  field size, it explains why we are in the mess we are currently in.

Navigation: Magnetic compass – Declination

The compass points north.

Being more specific the compass points to align itself the strongest magnetic field, which may or may not be grid north, usually not.

The north pole where all the lines of the map grid connect, sadly is not the magnet north pole, the same is true for the south pole.

The south pole is not even under Antarctica, it is not even covered in permanent ice, its just off the coast of Antarctica in the southern ocean.

With the right ship you could sail to the magnetic south pole.

So because of this you will need to add a correction factor (magnetic declination) based on exactly where you are on the earth (and years since map printed).

The world magnetic declination chart 2001

World Magnetic Declination map from 4.3Mb

So what does this mean?

This will show you how much you compass be away from grid north when pointing to magnetic north and whether magnet north will be to the east or west of grid north.


in the area of former French Indochina Vietnam Cambodia, Laos and Thailand there is very little magnetic variation, less than 1 degree, so in that area grid north and magnetic north are almost identical.

magnetic declination in Former french Indochina, Laos, Cambodia ,Burma, Vietnam. Almost less than 1 degree, magnetic and grid north almost the same

For the USA and Canada the situation is much more complex

In the east the declination is to the west and in the west the declination is to the east.

Magnetic declination for the USA and Canada

The declination becomes extreme in the  Alaska and western Canada areas.

Magnetic declination Alaska and western Canada

Here the declination becomes quite significant, in Banks island the declination is around 40 degrees, being that the difference between East and North-East is 45 degrees, you would not want to get this wrong.

Australia and New Zealand

Magnetic declination Australia and New Zealand.

The declination problem is as extreme as the case for North America, the real issue especially for Australia is the magnetic anomalies.

You might recall that Australia is (in many places) simply made from iron ore, and iron is magnetic.

Interestingly in Australia declination changes most significantly as you move east and west, in New Zealand declination changes most when you move north and south. further more both countries have a major city close to the line of no  yearly declination variation ( Brisbane and Auckland)

Changes in magnetic declination yearly

Magnetic declination (and the location of the magnetic poles) changes with time.

The measurements of change are in the above charts as light blue lines and are in the units of minutes per year ( 1 minute being 1/60 of a degree).

Here is an animation of the slow changes in declination over a 400 year period from the USGS.

Earth Magnetic Field Declination from 1590 to 1990

Please note the most recent data on the animation is from 1990 as i write this its 22 years out of date so the charts from 2001 are more accurate.

Find your declination based on your IP address

Manual calculation of declination changes

To do calculations on declination fist we must understand that the traditional navigation numerical system is
in base 60. Just like your wrist watch or clock, there are 60 minutes in an hour there are 60 minutes in an
degree. Change to declination due to shifts in the earths magnetic field are measured in minutes per year and just like declination itself, it is dependent on the position you are on the planet.

If you’re wondering where this numerical system came from, it came from Sumer, the first known civilization. While it seems like an awkward system at first, it is worth understanding, as it is completely embedded in geography, cartography navigation, astronomy and the measurement of time. Long after Sumerian was a dead language, scholars were studying Sumerian cuneiform to understand Sumerian knowledge of astronomy and cartography; all described in base 60: degrees, minutes and seconds.

Once a workable standard gets established, it gains considerable momentum.

For simplicity of mathematics we will arbitrarily assign east to positive declination and west to negative declination.  As north is considered to be 0 or 360 degrees on a compass this will make sence, 15 degrees east is +15 degrees 20 degrees west is 340 degrees (360 -20). Just like on a clock at midday it is 12 and the next hour is 1 and the previous hour is 11.

Math with degrees minutes and seconds
1 degree = 60 minutes = 3600 seconds
with notation
1°  = 60′ = 3600″

Example 1

Melbourne, Australia

In 2001 declination was 11.5 E; which is 11 degrees 30 minutes E.
Change in declination was 0.75 minutes per year E; which is 0 minutes 45 seconds.
Time passed since map drawn was 11 years

Total declination change 11 x 0’45″E

This is the same as saying how many minutes have passes in 11 45 second time periods.

11 x 45 seconds = 495 seconds

In minutes and seconds?

495 / 60  = 8.25   = 8 minutes 15 seconds ( 0.25 of a minute is a quarter of a minute, which is 15 seconds)

8′ 15″ E

Convert all E to + and all W to –

+11° 30′ + 0° 8′ 15″

+11° 38′ 15″

Convert + to E and – to W
11° 38′ 15″ E

Example 2

Banks Island, Canada

I selected a location where the declination line 39°E crossed the declination change 45′ W as a more extreme example
Time passed since map drawn was 11 years.

Total declination change 11 x 45′ W = 495′
How many degrees and minutes is this?
495/60 = degrees of change = 8.25 which is 8 15′ W
Interestingly the math was identical as before but the magnitude is 60 times larger.

Converting E to + and W to –

39° 0′ 8° 15′ = 30° 45′

Declination calculation in Degrees Minutes Seconds example

A hand written calculation of the example. please note the carry of the 6, which is really carry the 60 minutes

39° 00′ = 38° 60′

Because 1 degree = 60 minutes

+30° 45′
Convert + to E and – to W
30° 45′ E

So now that I have explained all of this and not even shown a picture of a compass you may be wondering about my logic.

Navigation by compass is not a simple affair, well not as simple as it appears once declination and declination change is taken into account.

The real importance of understanding declination becomes apparent once you are doing one or more of the following:

Traveling long distance.

Traveling on featureless terrain, desert, tundra, steeps, prairie, ocean.

Attempting to triangulate your position from landmarks.

Making decisions based on precise measurement of where north or south is, such as a sundial orientation or solar panel placement.

Using a very old map.

In a location with large annual declination change ( Canada, eh ).

Using a sextant.

Learn the parameters of your tools.

There is nothing worse than having too much faith in a tool you really don’t understand the subtleties of.

I will add that in trying to explain all of this, which was 24 hours of research and writing, I learned a lot.

I hope you have learned a lot too. You’ll never think about North the same way again.

Even so unless I’m on the ocean, I say the map is far more important than the compass.

Navigation: Astronomical Southern Hemisphere South

I was reading a gear list someone posted today and I thought it looked quite good, it even included a map and compass.

Then I realized while I have a compass, I don’t consider it essential.

I consider the map (especially if it is topographical ) essential but not the compass.
I can find my direction at night using the stars and during the day with the sun.

South at night with the stars:

For everyone in the northern hemisphere this is possibly redundant but explains an important point.

In the northern hemisphere finding the north pole star Polaris is quite simple, find the little dipper and follow the handle to Polaris that is always grid north.

This works because the pole star is quite bright and the little dipper is quite distinctive.

In the southern hemisphere not only is Polaris not visible, neither is the little dipper.

We don’t have a pole star but we have a bright distinctive crucifix pattern (Crux) called the southern cross which also has a pair of very bright star close to it Alpha and beta Centuri called ‘the pointers’.

Alpha Centuri is the brightest star in the southern hemisphere is its quite distinctive and is almost always visible.

A line imagined between the pointers if extended will intersect with the top star of the cross.

The long arm of the cross always point to the pole star , may be in any orientation in the sky as it rotates around the pole.

Once the cross is found you simple measure the major axis the longest line in the cross and extend this line out in the direction of the major axis 3.1 times and it will be intersecting with the pole star.

The from that point a line that is perpendicular to the horizon will be south.

The pole star may be visible or not depending on how good star viewing is on the night.

The point is this method help you find something you can’t see ( a non existent southern pole star) to find another thing you cant see ( grid south ) in the dark when you can’t see much anyway.

Quality knowledge allows you to do near impossible things.

One again proof of the idiom One picture, One thousand words.

How to find south using the stars in the southern hemisphere.

There is some debate as to whether  you should use 3 axes or 4 or 4.5, the reality is you will most likely be measuring with fingers spans and the width of your arm so its not that precise.  regardless if you are traveling at night you should be more worried about whats on the ground rather than the exact direction or south to the nearest degree.  If you used a compass you would have to convert magnetic south north to grid north and  you would be hoping for no nearby magnetic anomalies.

Update: having further examined this issue the correct number of axes to use is 3.53, but being that you will most likely be measuring with fingers between 3 and 4 is good enough. I will try to get an estimate of how large the cross axis will appear compared to an out stretched finger. From memory it’s about the width of two fingers.

Bicycle Power

200W 3 phase powered bike hub, 2x BR 354 rectifiers, 12 V 1 Farad capacitor, 12V lamp.

the picture is a gif animation click on it to see.

So me and a mate managed to get hold of some powered bicycle hubs. They are basically a 3 phase alternator built into an over size axle hub. Of course you can reverse the process and instead of adding electricity to get wheel rotation, you can spin the wheel and get electricity. The 3 phase AC needs to be rectified and smoothed a little with a capacitor (3 phase is smoother than single phase however).

The light pulses because the wheel is not constantly spinning. we later figured out we had wired up the capacitor backwards.

The work continues.

The original bulb pictured was an incandescent  indicator lamp from a car, essentially a tiny 12V light bulb. After some slightly energetic riding it actually burnt out, after glowing quite bright.  I estimated we were able to put 21W through the setup safely thought it (by pedaling slowly in top gear) though the bike is capable of a lot more.

The electrical diagram of the bike powered the light bulb.