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31  Using Arduino / General Electronics / Re: Power supply connection question on: June 04, 2014, 07:59:31 am
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Good luck trying to find a 3-pin outlet in the USA.

really?   I don't have any non 3 in in my house,
32  Using Arduino / General Electronics / Re: Soldering alternatives on: May 31, 2014, 02:16:27 pm

I'm also up there... 2 years your junior.  I totally understand how the eyesight gets worse.

 I have LOTS of light and would do a horrible job if it were not for my Hakko FX-888 iron. They are not super expensive and  It makes me a pro.  A good iron will let you be a good solderer... a bad iron will make even  a good solderer do a poor job. 

My checklist:
 1) right temperature for the job  2) clean tip (I use sal amoniac to clean my tip if it has any built up deposits) 3) good solder with a decent amount of integrated flux.

Keepitsimplestupid nailed it... apply solder to the heated part of the items to be soldered... not where the tip is (or to the iron)

Crossroads (Mike), I swear we used to be neighbors (off elm street) before I moved.
33  Using Arduino / General Electronics / Re: Short circuit broke my Arduino Mega? on: May 27, 2014, 07:53:16 pm
The USB polyfuse is supposed to be self-resetting...  but... it's possible that the USB-SERIAL bridge IC did not survive.
34  Using Arduino / General Electronics / Re: Short circuit broke my Arduino Mega? on: May 27, 2014, 03:01:36 pm
The Ramps 1.4 board is designed to move the motor load far away from the arduino board itself... but it won't protect you from shorting the 5V rail.
35  Using Arduino / General Electronics / Re: Short circuit broke my Arduino Mega? on: May 27, 2014, 02:55:37 pm
I suffered a similar issue while building my 3d Printer (wired up the Endstop sensor board wrong) and created a short.

The fix was easy.  I un soldered the LDO 5V regulator and replaced it with a new one.  Works fine now.

The way to avoid it is to be super careful.  In my case, I had used a bad reference document.

Note: It was just chance that I caught it fast enough that only the regulator fried.
36  Development / Other Software Development / Re: No drop down menu scrolling in the IDE on: April 21, 2014, 10:59:38 am
A sad truth...  smiley-cry
37  Using Arduino / General Electronics / Re: snubber circuit capacitor and resistor? on: April 14, 2014, 05:41:57 am
1/4 watt resistors will be fine

400V Metalized Polyester is probably the best choice/price for the capacitor.

38  Using Arduino / General Electronics / Re: relay circuit won't work? Please help on: March 29, 2014, 12:49:39 pm
For schematic drawings, I use an excellent piece of "Windows" software call SPLAN from German based developer.  I think Eagle schematics are awful.  There is no need to use all that red color when a nice black and white drawing is fine.

It's a fine product.  Custom parts are easy to add.  Most people pass it of as "not for them" because It's not free.  It's aimed at hobbyists.  I've used it for nearly 10 years and am still quite happy.  It is NOT integrated with PCB software... it is a drawing tool and I like it that way.  There is a demo version to see if you like it.

http://www.abacom-online.de/uk/html/splan.html.

39  Using Arduino / General Electronics / Re: relay circuit won't work? Please help on: March 28, 2014, 07:31:54 pm

40  Using Arduino / General Electronics / Re: Drive a led with NAND gate on: March 27, 2014, 08:56:53 am
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I wish you luck in your quest to convince the Internet that the 74HC595 *isn't* the key to driving multiple LEDs with Arduinos.

One read of the data sheet will explain why we are constantly abusing this poor IC.  If you draw 20mA per pin off of a HCT device continuously, you will certainly drive it outside the Absolute Maximum rating listed in the Datasheet and assuming harm is not done is just wishful thinking.

And for the curious, I have a retro collection of 74LS family logic chips... some of which I have "tested to destruction" on purpose to see how far outside Max Specs you can go before death.  Most chips are pretty hardy... but I have also seen chips perform ever so slightly differently after being abused if I didn't actually make it release smoke.
41  Using Arduino / General Electronics / Re: Drive a led with NAND gate on: March 27, 2014, 06:18:28 am
<gasp>  Electronics technicians and engineers have been getting it wrong for 50 years.  All those wasted resistors... the horror. <sarcasm off>

Yes, I'm being half serious here and not aiming my comments at you personally, but we constantly see people wanting to skip the current limiting part of a design by employing what I see as misguided rationalizations for why  a simple and inexpensive part can be omitted.

TTL Logic chips deliver logic level *signals* to other TTL logic chips.  Nothing in the design of a standard TTL logic chip is designed to drive non-standard loads (something other than another TTL logic chip) unless the chip has the word "buffer" or "driver" in its name.

Any other implementation constitutes "chip abuse" and while it may not be obvious right away... you are harming the chip (and likely the LED if it is a typical red one) when you ask  the chip output to deliver maximum unrestricted current to an LED.

It's not best practice. A well trained technician or engineer would not do it.   But how you abuse your own chips is your own problem and your own choice... just remember to buy more parts than you need.  And while you are at it, buy a big resistor assortment for say $9.00 and you will be all set for YEARS without having to come up with excuses about why you want to skip using a resistor.  They exist for a reason... Engineers don't design them into circuits to make things cost more or to just annoy people.
42  Using Arduino / General Electronics / Re: [Newb] What salvaged part can be used with arduino? on: March 27, 2014, 05:55:55 am
Learn how the parts work (resistor, capacitor, diode, etc)

Use common sense

Learn how to desolder without destroying ( Solder Sucker, desoldering braid etc)

Build a "junkbox" where you can collect 'sensible' recycled parts

Most of the parts in all of the devices you listed are ASIC  (Application Specific IC's)

Here is a quick guide.  If you can't find a Datasheet on a google search, don't bother.  If your device ran on 3.3V, you will need extra parts to level shift to the 5V of the arduino to make it work.

Best advice I can offer... Find much older electronics to salvage.  Ones that don't have Surface Mount parts... you may still be able to find some.
43  Using Arduino / General Electronics / Re: resistance fail on: March 26, 2014, 12:25:45 pm
A long time ago I did this chart... it might shed some light on what is being discussed.

44  Using Arduino / General Electronics / Re: resistance fail on: March 26, 2014, 09:03:51 am

I want to have a minor objection to a statement you made
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I understand giving something too much power and blowing it up

Power = Current * Voltage and it is a measure of "work".

I wish to clarify that providing too much power will not make something fail...  specifically.

You can provide too much voltage with a power supply and get bad things to happen if the load can't regulate that voltage .   You can provide too small a voltage with a power supply and very little will happen.  You can provide too little current with a power supply and likely burn up the power supply...  but you cannot provide too much current.   That is why I object to your statement about giving too much power to a load.   A load will only *draw* as much current as it needs. 

A short circuit is a form of failure where the power source is asked to supply an unrestricted amount of current between the two supply  connections, namely Power and GND.  As if a wire or component of high conductivity is place between the connections.  The unrestricted request for current will usually exceed the capacity of many parts, causing some rather catastrophic failures of at the very least... a fuse.
45  Using Arduino / General Electronics / Re: potting? silicone? epoxy coating? specifics on weather proofing Arduino circuit on: March 25, 2014, 09:15:43 pm
I think the tool dip/spray is called PlastiDip
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