You can find all the details at http://www.theharrogateshow.com/

Some time ago I presented my wife with a shop-bought wind chime and a promise that I could solarize it to make it ring whenever the sun came out. I’ve made these “sun chimes” before and in the depths of a British winter a cheery ringing to announce the sun is lovely. Its a nice project and (give or take a few months spent at the back of the workbench) – eventually turned out as planned.

Inside the sun cime

The motor mounted in the chime

There aren’t any certified celebratory plans as of yet but word has been mentioned that hangovers will be slept off during the bus trip down to EMFCamp the following day, by those who’re going!

There (may) be cake, ale, pizza, ale, possibly cider, if someone’s done a costco run, you can bring your own and just hang out with everyone on Saturday the 4th (this weekend!) The site should say when someone’s about as per usual if you’re a member and don’t have your own keys.

[ And stick the 21st in your calendar for our AGM :) -ed, Fligg]

ShrimpBot Parts

The picture on the right is a kit of parts for a ShrimpBot, a small low cost robot that could be your ideal introduction to the world of robotics – your very own robot! We’re considering running a workshop later in the year where we’ll be building ShrimpBots, but in order to ensure we have the right number of kits available we need some idea of how many kits to produce.

Assembled ShrimpBot frame

So, if you’d like to join the Leeds Hackspace Robot Army and be commander of all the desk you survey then leave us a comment here and we’ll make sure we produce enough kits!

We’re hoping a basic kit will be around £20, but it’s a flexible little beast so you can expand it with all manner of inputs and outputs as there are plenty of spare pins available, so you could outfit yours with a selection of sensors for detecting obstacles, following lines, or reacting to noises.

So, sign up now!

YOUR HACKSPACE NEEDS YOU!

ShrimpBot1 from Jon Stockill on Vimeo.

So I have a dial connected to an Arduino, a potentiometer (pot), it’s the typical item you might use for volume or brightness control, turning it all the way up to 11. Here’s the problem though, you’re reading in the analogue values of the potentiometer and you think it goes from 0 to 1023, possibly higher if it glitches a bit (though this is dependent on how it is handled in your code).

However, what you’re controlling, only goes from 0 to 10, maybe. What do you do?

Well one idea, is that you convert it to a percentage before making the comparison, I think this is effectively ‘normalising‘ the values – statistically speaking. This is really useful. So in this code I’m doing two things, one is that I am normalising the values but the other is that I am calibrating the values that I am reading.

Why should I be calibrating? Well, this code is then portable (the mathematics could apply to anything similar, as I see it), not only that but if the ‘pot’ needs replacing, then if it is placed in the ‘maximum’ value position for a while, then it’ll be accurate (well enough so).

#include "math.h"

int sensorPin = A0;
int maxVal = 0;
float sensorValue = 0.0f;
float percentile = 0.0f;
float temp = 0.0f;

void setup() {
 Serial.begin(9600);
}

void loop() {
 sensorValue = analogRead(sensorPin);
 percentile = (sensorValue / maxVal) * 100;
 temp = fmod(percentile,10.0);
 if (temp > 0.5)
 {
     percentile += 0.5;
 }
 if (percentile > 100.4)
 {
     maxVal++;
 }
 else
 {
     Serial.println((int)percentile);
 }
}

The code utilises the C++ Math library, and rounds the value from the pot up (I think, I should probably double check it) using the function ‘fmod‘. If the pot is set at the maximum it is capable of being at, it will increase the ‘maxVal’ variable to work out the correct 100% value to calculate with.

If anyone has feedback or corrections on this, please comment!

The first issue you run into when starting with PCB stuff is the layout of the board.  As an opensource fan, I wanted to use opensource applications, and this is an area that I found was problematic – KiCad is overly complex and expects a lot of prior knowledge, Eagle isn’t opensource (there’s a free version, with restrictions) and others are less established, crashy or require a lot of hoop-jumping to install.

I decided to go with Fritzing, which still has various issues, such as random crashing and a very “interesting” autorouter, and the fact that to get the latest, less-crashy version, you have to download the binary version from the website or compile your own (no ppa or packaged versions).

I found that the multi-step process of Fritzing (breadboard -> schematic -> pcb) was a great idea but some of the things I wanted were not breadboardy (isp header, 1mil sockets) and also the circuit I was building really benefits from a wide not long breadboard and those don’t exist in Fritzing. The main problem though is that when you finally lay out the PCB and connect what you want to connect, then hit the autoroute button, those it thinks are unroutable it disconnects.  Then you have to re-lay out the board and remember what connected to where. This lead me to a board with wrong routing that I manufactured.

Thankfully, all was not lost, we rescued the circuit, but I’m getting ahead of myself…  The method I used to make the board is a common one – print onto laser transparency, expose to UV (actually used a standard energy saver light), develop for about a minute and then etch in a tray of acid.

I then broke about 4 drill bits trying to use the pillar drill to drill the holes, finally resorting to a dremmel, which actually seems easier and about as accurate.

The "ShrimPCB" v1

Okay, so some of the holes were not perfect but that was to be expected.  I went ahead and soldered the board up and then was quite confused when it didn’t work.  With the help of one of the other hackers we located the causes – three routing errors in total, and some tracks were too close together, causing shorts.

Using a craft knife to cut tracks, using tracks that were aimed to be for the reset button (who needs that?!) and jump wires, we were pretty sure that the circuit was correct. Unfortunately, the board still didn’t work.

We scratched our heads a bit, followed the traces with a multimeter and then it struck what the problem was – the copper was on the wrong side of the board.  Effectively, the transparency was the wrong way round when the board was exposed, leading to a reversed chip layout.

Almost ready to throw the board away, we decided that the time spent on making the board would be well worth the two minutes to “deadbug” the circuit – effectively treat the dip chip as a surface-mount chip and solder it to the copper side.

The finished board looks fine if somewhat blurry here (apart from the fudged pins from inaccurate drilling and how is that arduino clone running blink without a chip?!) from the top :-

Top view, blurry, better pic will be uploaded later

Side on and from underneath though makes people squirm and draw back in horror!

Side View, showing board resting on chipBottom view, showing the mess it actually is

Bottom view, showing the mess it actually is

So version 2 will be so much better!

P.S. The reason for the word “ShrimPCB” is that I’m using the fantastic “Shrimp” project’s circuit as a base for this Arduino clone, once I have made a working version that doesn’t require the fixes as above, the fritzing and svg files will be on github and/or thingiverse.

Angus explains the workings of his Minecraft to PiFace hack.

We’ll be hosting the 3rd Leeds Raspberry Jam on the 16th Feb starting 12pm. Previous events have seen mini arcade systems, Raspberry Pi ports of classic games, and the amazing PiFace to Minecraft hack from Angus (As featured on Hack a Day!)

Edge Lit Acrylic Sign

If you forget where you are you can just check our new sign (yes, blue LEDs are a bit over-used, but it’s the Leeds Hackspace colour, so I couldn’t resist).

The sign is laser cut from 3mm transparent acrylic with a nice deep etch of the name and logo. The top edge of the acrylic has cutouts for a row of high brightness LEDs (U shaped holes that the LEDs fit snugly into in order to capture the maximum amount of their light output). The end result is rather nice. Now it just needs wiring to automatically turn on when the hackspace is occupied.

MendelMax Shaft Couplers

Our MendelMax 3D printer hasn’t even printed anything yet (The first extruder we fitted was unfortunately far from serviceable, and we’re still awaiting some parts for the replacement – a tried and tested design) but we’ve upgrading parts on it already. The printed shaft couplers never seemed particularly robust, and since we’ve got our lathe working it seemed like an excuse to produce something useful. I’m rather pleased with the result, they should be far more rigid than the printed parts they replace, and they’ll fit in rather nicely with the black and aluminium colour scheme.

A long friend of mine is a devout fanatic of the TMNT - collecting nigh everything available and it’s his 30th birthday this year near christmas. So myself and the girlfriend thought, what better than to give him something he cannot buy?

With Jo‘s talents in Fimo and the resources available to me, we decided upon figurines. However, these required weapons. With a bit of resourcefulness, soldering, patience and heavy hitting by myself and pbrook and some laser off-cuts we managed to produce something resembling the TMNT load-out:

They have since been touched up with a bit of paint to cover the initial attempts at soldering the metal pieces together and neaten up the blades from being hammered. The ‘grips’ on the swords may be lightly painted, to retain the look formed by squishing the metal under great pressure by a vice.

I’m quite happy with the result and the ‘chain’ for the nun-chucks, made by braiding wire together.

Update: Here are the finished items: