Blog – Page 6 of 24

Proof of Concept Solar Panel Sun Tracker

There are all sorts of commercially available sun trackers for solar panels but they are use sophisticated engineering / electronics.

Until now, there’s been nothing out there for the hobbyist. Have a look at this proof of concept video:

proof of concept Solar Panel Sun Tracker video

Details on driving the motor

Thanks to my good friend Bart, NightHawkInLight and NASA for one part of the solution…

The above video shows how to power the motor during the day for tracking the sun.

However, when the day draws to a close and the main solar panel is receiving no light, there’s still one thing left to do…

Resetting things ready for the following day

We have to drive the motor to rotate the plate another 180° to allow the inner tube to return to the starting position, resetting the solar panel so it points in the direction it was in at the start of the day.

That part is easy with the aid of a diode, reed switch and a magnet.

The Solar Lithium Ion Battery Charger module already has the capability to deliver power (from the battery) when darkness falls, so we use this power to drive the motor some more.

To stop the motor at the right time is where the diode, reed switch and magnet come into play:

sketch showing how the magnet and reed switch work in conjunction with the motor to return the inner tube to the bottom when dusk falls

When dusk falls, dark-activated power from the battery comes on. This drives the motor via the closed reed switch and the diode.

When the inner tube has returned to the bottom, the magnet activates the reed switch, opening it and cutting power to the motor. This leaves the inner tube at the bottom, with the main solar panel pointing in the direction it started at the beginning of the day.

When daylight arrives again, the secondary solar panels will once more start driving the motor as dictated by the sun’s position. The diode is there to protect the battery from any reverse voltage spikes generated by the motor.

I haven’t checked the exact operation of the secondary solar panels and motor yet, so another reed switch may be needed to prevent the dark activated power from leaking through them when the inner tube is being lowered by the motor.

That’s it for now. I’d love to hear your comments – especially if you spot any flaws!

Timer-delay Off Switch prototype

Written by team member, Mark Ridley

I’ve been working on and have now completed the prototype for the Timer-delay Off Switch.

It’s purpose is to conserve battery juice – especially handy as it gets later in the year and there’s not enough sunlight to fully charge the battery each day.

It’s being tested outside right now with my Solar Lithium Ion Battery Charger that’s powering two 5-LED strings.

I’m just waiting for another 1/2 hour-ish for it to switch the LED strings off.

Here’s a photo of an earlier incarnation while I was adjusting the timing. Either I can’t do sums or I’ve misunderstood how to work them out. Either way, check out my resistor Christmas tree!

resistor Christmas tree while adjusting the delay-to-off timings

It was made more difficult because I need to allow a switch to change the timing between a 5 hour interval and an 8 hour one.

I’ve got my prototype switched to 5 hours and the LED strings switched on at 18:35. It’s just coming up to 23:30, so I keep peering round the curtains to see if they’ve switched off yet.

23:31 Not yet…

23:35 Not yet…

While I’m waiting… reed switches are fragile! I used one in the housing I’m using, hot glued it on top of a steel washer so that the magnet to actuate it placed on the outside of the housing would have something to cling to.

A washer, as I found, is no good. The hole means you get poles on the inside of the hole and around the circumference. That means the reed switch wouldn’t work properly when the magnet was brought close.

(23:41 Not yet…)

So I tried to remove the hot glue and hardly touched the reed switch – alas, the glass casing of the reed switch broke. Boo hoo!

So when the replacement arrives, I’ll be using a small steel plate this time and not a washer.

23:45 Not yet… I guess this calls for a cup of tea 😉

As a side note, I notice that as the colours on the LED strings change, when it comes to blue, they’re very dim. From past experience I know this means that the battery voltage must be getting quite low – so the timer-delay off switch is really needed at this time of year when using a 1.5 Watt solar panel.

23:55 Not yet…

00:22 Yaay! They’ve switched off.

So that’s around 5 3/4 hours. How consistent is this? I’ll time it again tomorrow and update this post with the result.

Update: It’s now tomorrow and it took 5 1/2 hours to switch off this time.

See the now-completed project build tutorial for it here

Electronics projects for Kids 12+ and Adults

We’ve recently been working on a number of practical, related projects you can build giving you useful electronics light emitting diode (LED) gadgets.

Here’s a few photos taken from the projects that have been completed, just to give you an idea of what to expect:

Apart from the Memory Flash Reminder, which is a standalone project, the rest are all mix ‘n match modules. This one in particular is a great gift for grandparents – and there’s plenty of time to make it as a Christmas present 🙂

The mix ‘ match ones are all designed so you can build the ones you like and then hook them up in different ways to suit you.

And when you’ve made them, they make great gifts that people will love receiving (especially the fibre optics!)

There are still more in the works (LED strings and Timer-delay Off Switch coming next, night-time porch light coming later).

Where is Moji? A fun early-learners’ game app for iOS and Macs

I’m on a roll! After developing the More or Less app, it was easy for me to develop this new one.

Who is this game for?

I’ve aimed “Where is Moji?” squarely at early learners / younger pre-schoolers. It teaches them a critical skill: to recognise and then find one pattern hidden amongst a screenful of others.

To make it fun, I’ve chosen the emoji used in the game from

sports
animals and nature
transport
everyday objects

Dad and / or Mum can sit in and help them learn the names of the animals when they come up. Lots of learning opportunities are there to use.

For even more fun, when they find Moji, they’re rewarded with a funny cartoon sound and a visual reward of a fountain of coloured circles, cascading down the screen.

I’ve designed it so that the early runs and levels have fewer emojis, with the number increasing as the game progresses. If you’re feeling adventurous, you can try the setting for a big kids game, which has far more emojis and a faster bonus multiplier countdown,

The easy and hard modes I’ve included for both the Kids game and the Big Kids game means there’s always a challenge. What’s the difference? The hard mode has more emojis and a faster countdown so even if you have a great reaction time, you’ll struggle to hit the top scores.

Get yours…

Download “Where is Moji?” here:

See screenshots of the game and a demo video

When you start each run, the screen shows you the emoji you’re to find.

When you’re ready, tap “Go” and the level begins. Note that the emoji you’re to find is repeated just above the “Go” button in case, in the excitement of it all, you forget what you’re to find!

Kids Game: The emoji they’re to find is also shown in the scores panel

Take a look at this screenshot of the last level of the Kids Game (on the easy setting). It shows how the number of emojis has increased:

If you like, watch this video of a complete game being played on an iPad. It goes all the way up to getting on the high score table – with the cheer you hear when you do! (I’ve included a different high score table for BigKids, to keep them seperate.)

A complete Kids Game (on the easy setting) being played on iPad

Thinking about building an iOS app for Zazzle

We’re not quite sure what we can achieve via an iOS app and Zazzle so we’ve been digging around and having a play.

As part of that we developed a simple and fun app for iPhones and iPads aimed squarely at kids (big kids, too!)

It’s called More or Less Kid’s Game and teaches older preschoolers about the notion of more and less in a fun and exciting way.

Here’s a screenshot showing the core in action. In the previous screen to this one, the player was shown one of two emoji.

In this case (though you can’t tell) they were shown a flamingo. Now they have to decide whether there are more or less flamingoes than rhinos by pressing the More or the Less button. (Yes, we know it really ought to be more or fewer but we’re practicing being less pedantic!)

a screenshot of the main gameplay area of the More Or Less iOS app — A screen from our More or Less iOS app

If they don’t make up their mind quickly enough, after a short while the bonus multiplier starts to count down and the potential score for a right answer reduces.

If they choose correctly, they get a positive, funny cartoon sound and a visual celebration as a reward. The run score they get (the bonus multiplier X number of images) is then added to the total score for the level.

If not, they still get a funny cartoon sound – but no visual celebration and no score.

There are 5 levels and 4 runs per level.

If they play with Dad or Mum at their side, they can get help counting the emoji to find out whether there are more or less.

We’ve made it so that the earlier levels have fewer images with bigger differences between the numbers of each. As the game progresses, each level has more images and smaller differences between the numbers of each emoji shown.

Get More or Less here on the app store.