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16  Using Arduino / General Electronics / Re: first pcb try on: January 22, 2013, 05:16:57 am
Hear, hear, pwillard!

I've had a lot of fun over the years, making my own PCBs.

Now... they may not be brilliant, they may not often use SMT, they may not be "professional"... but they clear up my proto-boards for the NEXT project, and are reliable and robust. (How many times has my CCTV enabling circuit gone down because that wire has come out of the proto-board, AGAIN!?... note to self: Get the PCB for that finished, installed.)

Guidance for, to me, reasonable compromise between hopelessly amateur and hopelessly expensive tools and techniques...
17  Community / Bar Sport / Flattr- the next Facebook? on: January 22, 2013, 05:06:30 am
Heard about

When I say I wonder if it will be the next Facebook, I don't mean another evil empire imperiling your personal secuity and information, but I mean another "something big".

They've found a way that seems to be workable for you to give small amounts to people and organizations you come across on the web. Costs Euros 15 to give it a try. Easiest sign up I ever encountered. Seems "safe", seems to have a bit of a track record. (Thank you

For a review from a new-to-Flattr, old-to-computers person... me... go to...

Why posted here? Ever want to send thank$ in a u$eful form to some of the people who regularly answer questions at this forum? Are you minimally tech-capable? Flattr might be for you!

(I am also dying to see what an incoming Flattr looks like... yes, there is a button on my page (smiley-kitty) and all Flattr payouts happen on the last day of the calendar month... Part of the Cunning in their Little Plan, Baldrick, is that they have essentially re-invented the "clearing" mechanism used by the world's banks to make checks workable.... but this time on a micro-scale. Micro-finance... and others... re-invented lending, and earned its "father" a Nobel prize. Flattr may have re-invented the check (cheque) system, to establish a system for micro-gifts.)
18  Community / Bar Sport / Re: Why did fuse blow? (No, not a joke!) on: December 06, 2012, 07:11:50 pm
Imagine the filament as a short length of special high resistance, high melting point wire... which it is, but with fancy coiling.

The bulb fails when finally enough of the wire has sublimed away, or when a mechanical shock breaks it... it is brittle, etc.

If one of the ends of the wire, as it falls from its normal position hits the wrong part of the support structure, you get a path for the voltage through a shorter-than-intended piece of the "special" wire. Short piece. Less resistance. Higher current... high enough to trip breaker.
19  Using Arduino / General Electronics / Re: Relay wiring help/confirmation? on: November 30, 2012, 07:40:31 pm
Diodes ARE needed with relays... but on the other side. There should already be one in the little PCB you have.

Basics of relay diodes...

20  Using Arduino / Interfacing w/ Software on the Computer / Re: Communicating with Arduino via Serial on: November 30, 2012, 07:24:27 am
More on what you want to do at....

The PC-side code isn't written in C++, but the basic ideas are all there, and many specifics which will help you.
21  Using Arduino / Interfacing w/ Software on the Computer / Re: Problem when using Soft Serial and Serial connections at the same time. on: November 30, 2012, 07:22:11 am
I confess: I haven't read your post carefully... but... what may be helpful:

Use the "basic" connection (pins 0 and 1) JUST for uploading programs to your Arduino, and the "built in" serial monitor.

If you have any other serial comms wants, do them across other pins, using NewSoftSerial.

(Lots and lots... some good, some less good... on this from....
22  Using Arduino / Sensors / Re: Looking for remote control Tx/Rx on: November 30, 2012, 07:17:13 am
You need to decide: Do you "need" the remote to operate via radio signals... possible, but more work, hassles, to get working... or will an infra-red beam device do? Much easier to get working.
23  Using Arduino / Sensors / Re: RFID! on: November 30, 2012, 07:15:10 am
No promises... but at that price, I'd certainly give it a try, if I were you.

The following code... library-less... would probably need very little adapation, if any...

For the beginner, libraries are a mixed blessing. They have their place... but should be used in moderation!
24  Using Arduino / Sensors / Re: how to extract data from i button DS1923-F5# using arduino on: November 30, 2012, 07:10:35 am
If no one has already invented this wheel... which you should hope for!... there's LOTS (not for the faint hearted) on 1-Wire stuff, reading the datasheets, etc, at....


Be of good cheer! You can probably, for Arduino work, skip over all of the "addressing"/ "selecting" stuff covered in the pages mentioned above.
25  Using Arduino / General Electronics / Re: Help Finding LED Diffusion Cap on: November 30, 2012, 06:58:05 am
If you want the LED visible across a wider arc... at the inevitable price, however you achieve it, of at a lower brightness... then all you have to do is use a fine file or similar to flatten the end of the LED.
26  Using Arduino / General Electronics / Re: Arduino Pin Limits on: November 30, 2012, 06:55:57 am
You can get LCDs that only need two wires.

... and they are simpler to program. They cost a LITTLE more... but this is a wheel you DON'T have to reinvent, chores you can pay someone else (a little) to Deal With...

Your subject... "pin limits" made me think you might be interested in current limits, so, for anyone checking the thread for that, here's a neat little "gotcha"...

Each pin must not be asked to carry more than a certain current.

BUT! Even if you keep the current in every pin below that safe maximum, you can STILL get in trouble if you have too many pins near the per-pin maximum at once. There's a total-current-through pins, too, which is LESS than "number of pins TIMES max per pin"
27  Using Arduino / General Electronics / Re: Relay wiring help/confirmation? on: November 30, 2012, 06:49:29 am
a) I'd be very, very doubtful of proceeding with this... safety grounds. See...

... however, as you are likely to proceed anyway (<smiley-kitty>)... be very, very "pessimistic" about what "could happen". Enclose the relay board PROPERLY. Think hard about how you can reduce the chances of any interconnection between wires to Arduino and mains power lines. And make the whole thing physically robust.

b) Regarding interpretation of the diagram....

The three circlurlar things in squares with three wires out of them are meant to be "cross sections" of the cables for powering your heater. (Three: Live, neutral and earth (also sometimes called ground))

The top square is for the wire coming from the plug from which the electricity is coming.

The relay board is similar to the one you have... but has TWO relays... it is like two of your boards, one above the other. The diagram shows controlling two heaters. For your purposes, just "erase" the lower relay (blue rectangle), and the lower (on right) square-circle-3-wires.

Which leaves the "upper" (of the pair at the lower right) square-circle-3-wires. This is the cable TO your heater.
28  Community / Bar Sport / Re: Where to get a Due or Raspberry Pi for Xmas gift on: November 30, 2012, 05:12:58 am
Unless there's a special reason that it HAS to be a  Due, or (shudder), Pi....

Why not give relative a "mature", stable, does-most-things-Due-does Mega? (Others may know better, but, from Canada, I would go first to (Colorado) for any of this sort of stuff. Not always the VERY cheapest... but big enough to be reliable, to have a reputation to care for, good stock levels, etc. Prices usually good, too.

(I'd be VERY happy with a Mega, if you can't get one of the others in time! <smiley-kitty>)


For the Very Keen, the "latest and greatest" is, of course, "necessary"... but if you just want to support (or maybe inspire) someone's interest in this line of "play", what is wrong with Mega? It was the "must have latest-and-greatest" not so long ago. (I am still on PRE-Mega Arduinos, and have LOTS of fun! And I'm no newbie... see

I admire the Pi team for "having a go"... and a part of me wishes them some luck. But why dump your relative in the land of the "getting started" when the Arduino is so well advanced? The Pi is NOT "this generation's BBC Micro". It is NOT "very simple". Dig around the net for "getting started with your Pi" articles, and for the "these are the things you need to get right" and the "this is how you can fry it" articles....
29  Community / Bar Sport / Re: Why did fuse blow? (No, not a joke!) on: November 30, 2012, 05:03:45 am
But why, then, does fuse NOT blow when the thing is merely switched off? Is the switch more than a fancy and convenient way of "unplugging"?

But I'm encouraged that you, too, seem to be headed towards the "collapsing fields" theory.

Maybe a brief "re-make" of the contact, at just the wrong moment in the "fields collapsing" process creates a "clash" between what the grid is supplying and the voltages inside the very-recently-disconnected motor? (A "re-make" which the switch is properly designed to avoid?) If that makes sense, can anyone express it more accurately?
30  Community / Bar Sport / Re: Why did fuse blow? (No, not a joke!) on: November 29, 2012, 01:37:13 pm
Good idea... thank you... but I am fairly careful about frayed wires, wire wiskers, loose plugs.

(Writing that inspired me to go Try Again to find the wretched pin. Found it. Fan working fine. Wiggled wire, both ends... no problem.)

Something to do with "switch bounce"... circuit between socket and plug breaking, then re-making in a moment, during the unplugging process? How would that cause current surge? Yes, I THINK it "could" be collapsing fields around the motor coils. Does anyone KNOW that could be it? Any other ideas?

Just curious... don't "need" the answers. Sad, but not that sad.

Saw the spectacular results of a short in a vacuum cleaner in the US, no fuse-in-plug... a series of sinusoidal deep scorch marks on carpet. (I was firefighter at time). The (spiralling) wire inside the 50' cable had flashed VERY hot, along the whole length of the cable, giving rise to the scorch marks described.

Any other ideas?
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