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16  Development / Suggestions for the Arduino Project / Re: Taller headers for Ethernet Shield on: May 17, 2011, 02:19:27 pm


If you get a set of headers from one of the usual suppliers you can use them as extensions between the shields.
It effectively raises the shield one shield height giving plenty of space.

Gordon
17  General Category / General Discussion / Re: Good forum to ask workshop tool questions? on: March 23, 2011, 04:08:18 pm

Im no expert, but I wondered this myself.
My research/searches came up with the conclusion that the bearings and build of the drill will not take the lateral forces for long before failing.
Also the bearings are not accurate enough.
I believe the term is runout its the amount the tip of the tool can move from true.
My bench drill has a visible runout at the drill tip as its a fairly cheap model from machine mart.
Also the chuck is a press fit, not always pressed straight and true.
Also the lateral forces can loosen the chuck on its taper fitting and you can get a large lump of metal with a sharp tool attached to it flying across the room.

Sorry for the bad news.

Gordon
18  Using Arduino / Motors, Mechanics, and Power / Re: Powering 3 servos & what's everyone using on their workbench? on: March 03, 2011, 10:51:09 am

I vote for PC power supplies.
You can do a lot with them.
Heres mine as is stands now.
http://scratchpad.thisandthose.org/scratchpad/article.php?story=20110224160501815

Gordon
19  Using Arduino / Networking, Protocols, and Devices / Re: easy networking - used netbook on: March 01, 2011, 10:12:15 am

But then you defeat the purpose of using a small cheap microcontroller.
You can build your own supporting peripherals for a fraction of the price of the pre built shields.

Introducing another massively more powerful processor just to act as an ethernet shield seems bit of a waste to me. Once you introduce something like a netbook you might as well remove the arduino and run everything from the netbook directly. Then you can use multi threaded processes and real time o/s.


Gordon

20  Community / Exhibition / Gallery / Re: Yet another home built ATX power supply for my Arduino projects on: February 24, 2011, 04:04:04 pm

Yes I scraped it, and in a couple of other places.
You are supposed to be able to put a clear lacquer over the top but this was my first attempt.
Next time or if I redo it Ill lacquer it.

I got it from a seller on ebay. I think this was the guy.
http://cgi.ebay.co.uk/140513491603

Gordon
21  Community / Exhibition / Gallery / Yet another home built ATX power supply for my Arduino projects on: February 24, 2011, 01:00:37 pm

Ive finally finished building a power supply for my Arduino projects and supporting circuitry.
I got fed up of using wall warts so I read up about using ATX computer power supplies and built my own.
Im really pleased with how its turned out as its the best enclosure Ive made so far.
The front panel turned out very tidy.

12v, 9v, 2x5v, 3.5v and a variable supply with meter.
All switched and LED indicators.


http://scratchpad.thisandthose.org/scratchpad/article.php?story=20110224160501815

Gordon
22  General Category / General Discussion / Re: PCB diy on: February 19, 2011, 10:25:23 am


I use the thicker magazine paper from the better quality magazines.
Tear out a page with just text on it. Large blocks of colour or black make it harder to see through.
It wont pass through the printer like this so tape it to an a4 sheet of paper with masking tape ensuring the tape dosnt go outside the a4 sheet.
You will read that some have had good results with some photo papers but I couldnt get it to work the toner would not stick to the paper and just made a mess. Old magazines are free!
You can buy special toner transfer paper, but it is expensive.

The ferric chloride needs to be diluted as per the instructions on the bottle.
and yes it is better to rock the container as it will speed up the process.
You want a fairly strong solution so that the etching works quickly and is less likely to undercut the toner mask and keep your traces nice and crisp.
Just keep checking the board until all of the un masked copper is gone.
Its fairly obvious and quite magical to watch the first time you do it.

You can make yourself a bubble tank with a taller thinner container and an air pump from a fish tank but Ive had good results just by rocking the container. All you are doing is moving the fluid so that less saturated solution moves over the board and keeps the reaction going.

Like I said have a good read through the guides until you understand the process.

Gordon
23  General Category / General Discussion / Re: PCB diy on: February 19, 2011, 06:19:43 am

Google for tutorials on "toner transfer" methods.
You need a laser printer or good quality photo copier, your school will have one Im sure.

Read several tutorials they are all slightly different and you can piece together a method to suit your resources.
Each of the steps are documented repeatedly in different guides.

For example,
I use eagle to produce my design for the board.
I print it out on a samsung laser printer on to magazine paper. You will have to experiment with the paper.
The paper is the key part of a successful board with the toner transfer method.
I tape the transfer to the pcb. Single sided nice and easy, double sided take time to line it up.
Ive had very good results with double sided but it is fiddly and may take more than one attempt to line it up properly. But at this stage you can just clean of the toner and try again.
I use an old cheap laminater to heat and transfer onto the board, you can use a domestic iron, Laminater is easier for me and cost about £10.00. I pass the board and transfer through about 6 times turning it over.
I use ferric chloride solution to etch in a sealed tupperware box. You can seal it up and use it again
If any of the traces are a bit sketchy touch it up with an etch resist marker pen, or marker pen, sharpies are quite good.

Heres one I did earlier:
http://scratchpad.thisandthose.org/scratchpad/article.php?story=20100715160140327
This was only about my 4th attempt at a board.
Double sided and fairly fine traces, just one small mistake on one pad on the wrong side of the board. So theres no reason why you shouldnt be able to do something similar with a little research and practice.

I could give you a list of resources but you would get the same results from googling "Toner transfer method".
http://www.google.co.uk/#q=toner+transfer+method

Good luck,

Gordon
24  Using Arduino / Motors, Mechanics, and Power / Re: Best overall servo? on: February 13, 2011, 08:35:14 am


Have you had a look at the OpenServo project.

You can take a cheaperer servo's and give it some advanced features.
It can give you better control and feadback from the servo.
It uses I2C instead of direct pwm from the controller so you can string them on the same bus and save pins for other uses.
http://www.openservo.org/

Gordon
25  Community / Bar Sport / Re: Visiting London - what to see? on: February 09, 2011, 04:18:56 pm

Science Museum
Natural history museum
Victoria and Albert Museum
All together in Kensington and well worth a look.
http://www.londontoolkit.com/whattodo/southkensingtonmuseums.htm

Tate Modern
One of the best modern art museums in the world.
http://maps.google.com/maps/place?client=ubuntu&channel=fs&oe=utf-8&um=1&ie=UTF-8&q=tate+modern&fb=1&hq=tate+modern&cid=2304839309186538471

Design museum, Close to Tower bridge.
I didnt think Id like this but it turned out to be very good.
http://maps.google.com/maps/place?client=ubuntu&channel=fs&oe=utf-8&um=1&ie=UTF-8&q=design+museum+london&fb=1&hq=design+museum+london&hnear=design+museum+london&cid=12569867610224080166

Gordon
26  General Category / General Discussion / Re: A UK arduino newbie joins the fray (with a question or two) on: February 09, 2011, 12:49:54 pm


Depending on where you are, have you thought of hooking up with one of the Hacklabs springing up?
Maybe they would be able to help with a school club.
They are always looking at ways to expand membership and advertise there existence.
http://hackerspaces.org/wiki/List_of_Hacker_Spaces
They are local community groups.

I know the London east end lab is running Arduino weekends.

Gordon
27  Using Arduino / Project Guidance / Re: Solar Panel & Battery Recharger on: February 08, 2011, 12:49:34 pm

You need a charge regulator.
I use a 12v lead acid leisure battery for camping with a solar panel to keep it charged.
We get all of our lighting and charging of phones and mp3 players of this even in the UK.
The controller cost me about £30.00 it was worth it.
You connect the battery to one set of terminals.
The solar panel to the next and the load to the next set of terminals.
Handles all the charging and load for you.

Something like this:
http://www.maplin.co.uk/charge-controllers-97384?ordercode=L22BR
You will have to pick one to match your battery and panel.

Gordon

28  Using Arduino / Sensors / Re: Matrix Keypad with fewer pins? on: February 05, 2011, 06:10:30 am


I havnt used that keypad but if its got the usual pinouts it should be fine with that I2C controller.
The lcd is fine as well, or you could use a similar 4x20.

There are loads of examples for using the keypad and lcd through I2C.

Gordon
29  Using Arduino / Sensors / Re: Matrix Keypad with fewer pins? on: February 04, 2011, 12:59:28 pm

As you want an LCD as well, How about one of the Serial/I2C controllers with combined support for the keypad.
Then its just 2 pins plus supply and ground.
Includes all the backlighting and contrast adjustment.
http://cgi.ebay.co.uk/I2C-Keypad-controller-LCD-Character-Display-/310275043982?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item483dd5728e

Libraries available as well.
Ive had a play and it works well.

Gordon
30  General Category / General Discussion / Re: PCB diy on: February 03, 2011, 10:31:41 am


Not much so far, but if washed it down quickly.
Now battery acid is another matter, as was the glare I got from the wife.

Gordon
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