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121  Community / Bar Sport / Re: Students caught out.... on: July 02, 2014, 11:36:22 pm
I was thinking flux, not paste. They have flux.

These guys ship free and I always get my stuff in 20 to 30 days.
Yes. I can vouch for DX. Never had any problems with them and my orders arrive, sometimes, in 12-14 days. But I do wish that they'd give more detailed specs for their products on their website.
122  Community / Bar Sport / Re: Question about FAQ and Open Hardware. on: July 02, 2014, 11:24:13 pm
Correct, Ugggly englishman.
Last time I looked, Anchorage was not in any of Her Majesty's Overseas Dominions, Possessions and Territories.
If anything, last time it was owned by anyone, it was by a Tzar.
Technically, since the Tzar sold it, it belongs to the buyer. And I agree that it is not, nor has it ever been, British.
123  Using Arduino / General Electronics / Re: infrared optical sensor, AS A SPEED SENSOR? on: July 02, 2014, 10:53:33 pm
Hi, You can use an infrared optical sensor, AS A SPEED SENSOR?
Yes. My infrared mouse does it, no problem.
124  Using Arduino / Project Guidance / Re: Whiskey dispenser on: July 02, 2014, 10:22:33 pm
Just a minor point to watch out for. You can't suck water up more than 32 feet or mercury more than about a Metre, however powerful your pump is. I don't know if anyone has done the necessary experiment to determine the maximum height for whiskey, but it would be an 'interesting' experiment to do.  smiley
125  Community / Bar Sport / Re: Is it just me, or.... on: July 02, 2014, 12:35:16 am
..... are there a lot of Voice Recognition questions today. All in the same class at the same school?
Sorry. What did you say?  smiley-mr-green

WILL       IT      HELP      IF        I        SPEAK       SLOWLY     AND     E        NUN      CI     ATE        MY      WORDS?
126  Community / Bar Sport / Re: Students caught out.... on: July 02, 2014, 12:21:59 am
We did.  Not sure if there are any left.  The two I knew of are gone.

While I would assume you could pick up a roll of solder there, does RS actually carry solder paste?
I don't shop RS all that often, particularly since I moved offices, and it isn't on the way home, I decided to check.  RS has two different solder pastes listed in the web inter-tubes.  There are 3 RS's still operating within 10 miles of my home, and the web claims that the 2 oz. Non-Spill Rosin Soldering Paste Flux is at each of the 3 RS, while the SP-30 Acid Paste Flux 2 oz. is online only.
Flux is not the same as solder paste (used for SMDs). Solder paste has powdered solder in it, flux doesn't.
127  Community / Bar Sport / Re: Students caught out.... on: July 02, 2014, 12:16:36 am
After about 30 minutes of this back and forth, he eventually found some.

Consider yourself lucky - my nearest Maplins doesn't do discrete components. PA systems, fog machines, yes. Resistors in packs, yes. 7805? No way!
Are you certain? There's usually a counter at the back of the shop with the individual components hidden away behind it. I now usually look up their product number on-line before I go there. It doesn't always help though! I wanted 2 Mtrs of 6 core cable. They knew what I wanted, and they knew they had it in stock, but they had to look through several dozen reels of cable before they found it.  smiley-mad smiley-mad
128  Community / Bar Sport / Re: Students caught out.... on: July 02, 2014, 12:01:36 am
In most cases, an online retailer just makes sense.  It's hard enough keeping prices and inventory competitive when you're selling to a whole country (or continent or planet.)  However, I was reminded of the disadvantages to this approach when I was shopping for solder paste.  US Postal Service restricts sending stuff like that (and coin cell batteries...) via air mail.
If you bought it from China, would they know what was in the packet? Shhhh!  Everything I buy from there is marked as 'gift'.   smiley-wink
Shipping to my state via one of the major carriers (FedUps) would start at $40.
Tell me about it! I needed a US$3 item from Adafruit. Local suppliers didn't stock it. I could have bought it from Adafruit, but the shipping to the UK was another $12! In the end I managed to get one from China with free shipping for about $2.50.
Now, given that solder paste has a short shelf life and is sold to a fairly niche market, how likely is it that I'll find that in a local shop?  If we still used brick-n-mortar stores as primary source, maybe non-zero.  But now?  Nuh uh.
Another advantage of independent bricks and mortar shops is that the owner/staff knew what they were talking about and you could get good advice there. That's not as easy over the intertubes.
129  Using Arduino / General Electronics / Re: CONFUSING RELAY TO RELAY CONNECTION on: July 01, 2014, 11:23:22 pm
  "if there are no internal reasons for the connections AND
  nothing bad happens when the two devices have signal wire on the different terminals"

what do u mean by internal reasons for the connections sir ?
He means that the device only has a simple make or break contact with nothing else connected internally to those contacts.
but i think the devices' internal contacts are not carrying both the load of the relay, i think it is only carrying the power supply (12V 1A) intended for the dpdt relay ONLY sir if i'm not mistaken .
You are not mistaken. The receivers are on a completely separate circuit from the contacts of the DPDT relay.
because the internal contacts of the device can only handle 15W contact rating, whereby the 2 output devices are rated at a total of 22W ... i'm triggering the internal contacts of the devices for more than 10 times a day , and nothing bad happens ...i just want to know if it will last long without future troubleshooting .. but there will be of course as time goes by . and i also want to know where are these potential spots that will need troubleshooting in the future . tnx
It looks perfectly OK to me. For consistency, I would swap the wires to 3 and 5 on one of the receivers (so that the common is +ve on both), but it won't make any difference to the working.
130  Using Arduino / Programming Questions / Re: prototype function error on: July 01, 2014, 10:53:41 pm
@AWOL, Henry_Best:

weird, isn't it.
Boy, howdy, neighbor, it is.
Neighbour? Is he only a skein's length away from you?
131  Using Arduino / Programming Questions / Re: Is it possible to re-#define something? on: July 01, 2014, 10:32:52 pm
Why not save the modified file under a different name, such as mywiring.c, so that it doesn't overwrite the original wiring.c and affect other projects?

How would the IDE know to use that instead of wiring.c?  I would imagine if I tried to include it I would get all kinds of duplicate function/variable definition errors.
How will the compiler know about the existence of the original if you just include the modified one and not the original?
132  Using Arduino / Programming Questions / Re: break;... is it broken? on: July 01, 2014, 10:18:38 pm
In my opinion, if what you want to do is stop the execution of the program, one thing that you can do is:
   if (some_condition) {
      while (1)

This will cause the execution of the program to stop, because if the condition is satisfied the execution will "fall" in one "repeat for ever" loop.

I don't know if something like this will work for you.
Another way you could try:
boolean failed = 0; //boolean false
void loop(){
  if(failed== 0){
  ///do the rest of your code and
  //set failed to 1 (boolean true) if condition met
loop() will still run continuously, but will skip over your code if there has been a failure.
Remember, though, that with both these methods you'll have to do a reset or power off to get it doing something useful again.
133  Community / Bar Sport / Re: Is it just me, or.... on: July 01, 2014, 12:05:56 am
..... are there a lot of Voice Recognition questions today. All in the same class at the same school?
Sorry. What did you say?  smiley-mr-green
134  Community / Bar Sport / Re: Students caught out.... on: July 01, 2014, 12:02:19 am
I was at my favourite supplier on the way home and he told me this salutary story:

Seems a few uni students were in the shop a while ago, buying parts for a project.
You mean that you still have independent suppliers with physical shops in S.Africa!?!?
You're lucky.
We have one chain here, Maplins, with physical shops. All the rest are on-line, virtual stores.
The last independent physical electronics parts shop near me closed last year because the owner hung himself in the shop. I was told that this was because he was losing money. As far as I know, there are no longer any independent physical electronics parts shops in the whole of London.

Maplins employ staff that know nothing about electronics. I went into my local branch and asked, at the components counter, for a 12 V regulator. The assistant came back, from elsewhere in the shop, with a box that appeared to be a fitting for a car!
"NO. I want a 7812."
"What's that?"
"A three pin integrated circuit."
"What does it look like?"
I didn't want to confuse him by telling him "It looks like a TIP120".  smiley
After about 30 minutes of this back and forth, he eventually found some.
It doesn't inspire confidence when asking, for instance, about a component's parameters!
135  Community / Bar Sport / Re: Question about FAQ and Open Hardware. on: June 30, 2014, 11:04:50 pm
Ok to improve my CV the next website I will done for the Satan Church  smiley-evil smiley-razz
But you've told us that you've already done work for the Vatican!
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