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31  Community / Bar Sport / Why did fuse blow? (No, not a joke!) on: November 29, 2012, 12:24:21 pm
I live in the UK.

Here, anything powered by "the mains"... i.e. "household voltage"...  "plug it in to a socket" (thank you, Mr Hubbell... they had to be INVENTED... plugs, sockets! Ever think about that?)... things have a fuse IN THE PLUG. There are also fuses on the whole circuit, of course... but the fuse-in-the-plug IS a good idea, really.

Anyway... just now, I unplugged a "fan heater"... a combination of fan + electric heating element, for space heating. I didn't turn off before unplugging. For some reason, this caused the 13 amp fuse in the plug to blow. (Over 13A flowed at 230v AC, running a motor and a piece of hot-at-the-time resistance wire.) WHY? There WAS a "flash" as the pins came out of the socket. But what would have caused a current surge as the circuit was disconnected? I don't THINK that as I unplugged, the resistance wire broke, shorted out to fan's case, etc. Collapsing field in motor? But why no fatal surge when I "disconnect" more elegantly... with the switch?

I'm sure someone out there can tell me?

(I'd check the matter of whether the wire broke and shorted, except that as I opened the plug to replace the fuse, I dropped one of the plug's pins... IN my house... not "out in the garden" or something... and CAN'T FIND IT. (Just not my day in general. Using fan heater because central heating has been out for 10 days, waiting for a part, and the part came this morning... didn't fix problem. Two instances of the part, actually, as I'd got fed up waiting for first supplier.))


(Oh yes... and when the fuse blew, the circuit's breaker went, too... taking down a computer with several open projects on it. THANK HEAVENS: I HAD saved one essay which would have been a heartbreak to lose.) I'll let you know when I start having fun.
32  Topics / Robotics / Be inspired- Hamburg model railway on: November 26, 2012, 03:57:46 am
No "question" here, and I don't know if the twins who created it use Arduinos, but if you visit...

(or, if YouTube isn't your thing...)

... you'll see an amazing model train setup. Actually, I should say "trains"… there are 890 of them (over 11,000 carriages) in this amazing layout in Hamburg Germany.

Trains and cars and boats and airplanes!

The YouTube clip is pretty amazing in itself. Sadly only a glimpse of the electronic control systems... maybe an Arudino person could undertake a "tour for techies"!
33  Using Arduino / General Electronics / Re: Why do electronics "burn"/"get fried"? on: November 20, 2012, 10:36:19 am
You may be at the stage I was at for YEARS... thinking that current WILL somehow "force itself" into a component.

Current is what happens AFTER you have set up the voltage and resistance of a given situation.

(That sounds so simple. Sadly, it isn't. Voltage isn't always what you would think it "should" be, and wen you get to the point of burning things, resistance "goes funny" too... but you might find....

... useful, anyway.
34  Using Arduino / Sensors / Re: Cheap alternative to Thermocouples? on: November 20, 2012, 10:27:49 am
Unless you really need such a wide sensing range, the Dallas 1-Wire chips are MUCH better... at not a great deal more complexity to use.

DS18B20 range: -10C to +85C

Yes... they take a little "getting to grips with"... but once you're there, you have an easy, reliable, high prescision... at the end of long wires... sensor.

And "DS1820" must be code for "Viagra" for the number of auctions you'll find on eBay for the things!
35  Using Arduino / Networking, Protocols, and Devices / 433MHz HomeEasy (ByeBye) receiver offered for sale on: October 18, 2012, 03:31:29 am
I have an unused HE-106X receiver module which is surplus to my needs. You'll find libraries on the forum/ playground for the HomeEasy line, which overlaps several others, e.g. ByeBye. Nicely made. Screw terminal connection to power, outputs.

Complete with "instructions"... patchy, and Chinglish, but not entirely useless. I will send them with the unit. The instructions also specify 12v 800mA for the receiver.

433MHz. The unit seems to output via a relay, and NO and NC poles are available.

I am hoping you are in the UK, so posting isn't a hassle, but will consider others. Not heavy.

To encourage you to pay a bit more, I would accept a cheque payable to some US or UK charity to cover both the unit and the postage of it to you.

Intereseted? Suggest three "big" charities for me to chose between... hopefully in different fields!... and what the unit is worth to you on those terms?
36  Using Arduino / Networking, Protocols, and Devices / Re: Periodic LED and on demand on: October 09, 2012, 05:09:30 pm
Another approach is as follows...

Work things so that your "loop" executes 100 times per second, or so.

And have your "on for a bit" LED go on for 50 passes through the loop, if you want it on for 0.5 second. (You can do this with a variable you might call bCountDownToOff... set it to 50 when you turn the LED on, decrement it (subtract 1) each time you go through "loop", and turn LED off when bCountDownToOff reaches zero.
37  Using Arduino / Networking, Protocols, and Devices / Re: Ethernet Shield connect to internet on: October 09, 2012, 05:06:32 pm
When you said...

When i type the http://192,168,10,103 in my PC browser i get the data from the arduino via a simple html script.

... I'm assuming that you meant some simple html served up from the Arduino?

In which case, you've made a very good start.

To access that from "the outside world", is not TERRIBLY difficult... perhaps the biggest issue being how to know "where" your router is, i.e. it's (current) IP address in the wider world of "the internet", i.e. NOT its LOCAL IP address, the one that probably starts 192.168...

"The answer" is often to use a DYNDNS service.

Use of DMZ not always necessary... but you probably DO want to set aside some addresses on your LAN as NOT used by the router's DCHP service. Confused yet? Sigh.

Much more on all of these topics at...

... but you have ALREADY CRACKED half of your problems! Alternatively, my FarWatch pages may be more to your taste... cover the same topics..
38  Topics / Home Automation and Networked Objects / Re: Setting things up in Europe on: October 04, 2012, 02:28:50 am
There are X-10 units sold for use here in the UK... but I don't know if there's a difference again between here and Spain, though. Just trying to be encouraging!
39  Using Arduino / Sensors / Re: Get value from RFID tag and store it as a string on: October 04, 2012, 02:17:58 am
40  Using Arduino / Sensors / Re: Help reliably reading switch on long wire on: October 03, 2012, 07:29:42 am
For two metres of shielded twisted pair cable, just go down to your local Radio Shack/ hi-fi store and buy some audio cable.
41  Using Arduino / Sensors / IP Cams with external trigger on: October 02, 2012, 09:00:18 am
Yes! I know this is the Arduino forum... bear with me?....

By chance, I came across an IP Cam with an external trigger... by hooking up a switch, you could make the IP Cam take a snapshot when the switch was pressed.

After many, many hours of trying to make motion detection, etc, built into various web cams, ip cams, CCTV software, etc, etc, I WANT TO DO IT MYSELF!! (Fed up! Forgive the shouting?)

(P.S.: Ooops... Why this is an Arduino post, in case that's not clear yet: I would generate the "take picture" signal to go to the camera with an Arduino... in fact I am already using one that way via the LED trick explained below.)

If I had a decent IP cam which would respond as the one I have is supposed to respond, I would at least be able to start banging my head against a different wall.

Anyone know of a GOOD ip cam, hobbyist price... say under $120, eBay... which such a feature?

Not, please, the Foscam/ Wansview/ Wanscam/ Storage Options/ Shinntto/ Tenvis clones.

Something reliable? Linksys? Panasonic? DLink? Logitech?

And, just to amuse you... I've found a way to "cheat" with some cams: Put an LED close to a camera, in the corner of the field of view. If the camera allows you to specify the area to watch for "movement", you can (try to) use its built in "motion detection", and trip the camera by turning the LED on or off.

"Catch-22": Want to use motion detection for a view of passing wildlife? It will "catch" the animal... mostly (and moving shadows, etc, etc)... but it will also, almost immediately, take another picture: The EMPTY scene which arises just after the animal has left. Sigh.

Not a problem if you are just collecting images... although you have a lot to discard... but it IS a problem if you have something like....

... where, SOMEDAY, the images will be of the most recent INTERESTING views. Sigh.

Remember, please!! The question was: What IP Cams have external "take picture" inputs. Feel free to start new threads, if any of my ramblings strike you as worth discussion?

42  Using Arduino / Sensors / Re: Sound sensor to servo on: October 02, 2012, 08:44:25 am
Always divide any such project... and questions arising (<smiley-kitty>) into it's parts...

In this case...

a) How to get a number inside the Arduino from a sound level
b) How to make a server go to a position, based on a number you have.
43  Using Arduino / Sensors / Re: External tank level sensing via density ? on: October 02, 2012, 08:42:18 am
density of water does not change

True.. within the context of the discussion...

But I bet water on the other side of the tank wall changes the capacitative environment at that point on the sensor... perhaps because(?) of the density of the substance there, water, rather than air. Or some other property of the two, but, bottom line, idea for sensing level MIGHT work...

The OP may have heard of level sensor which work based on the OPTICAL density of fluids, and their effect on beams of light bouncing... or not bouncing... around inside prisms. This is used in ink jet cartridges, Canon for one. But the prism has to be in direct contact with the contents of the tank.
44  Using Arduino / Sensors / Re: Help reliably reading switch on long wire on: October 02, 2012, 08:38:02 am
How much trouble is this worth to you...

Here's a very robust (I think... never tried it... but based on other stuff about long wire monitoring) "answer" for you:

With a different switch at the other end, at the "sense it" end, you could arrange for the voltages on the end of the wire NEAR... not directly connected to!!... the Arduino, call them "A" and "B", to be powered "one way" or "the other", depending on switch position.

Switch "on": A is positive with respect to B
Switch "off": B is positive with respect to A

Once that is in place, near the Arduino, you wire up a comparator circuit with a digital output to the Arduino.

Less involved thing to try:

At Arduino, a small circuit based around an opto-isolator...

... and drive the LED in that with a larger voltage than the voltage you are currently using. (Larger voltage= more room for "must be higher than".)

The same circuit could incorporate a capacitor/ resistor on the LED side to discard transients.
45  Using Arduino / Networking, Protocols, and Devices / Re: How to detect objects presence and distance <10m, simple and low power ? on: September 27, 2012, 07:51:16 am
This would be a job for...

... if that circuit ever gets INTO PRODUCTION!!!

You could consider doing your own version of the same idea.
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