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1  Development / Suggestions for the Arduino Project / Re: Arduino PCB on: April 13, 2014, 09:44:31 am
sounds like the sort of project that needs good video output and mouse / tablet input,
     and some way of drawing the pcb, like 3d printing,

might be a little out side the capability of the arduino, more PC power ,
2  Using Arduino / General Electronics / Re: PECL/ECL Logic on: March 19, 2014, 02:36:21 pm
looks to me like you have a digital output that is

High is : Vcc - 1.085  to Vcc -0.88

Low is : Vcc - 1.83  to Vcc - 1.55

Cheep and slow, stuff this into the analog input on the Arduino,
     
else,
   get a converter chip,

3  Using Arduino / General Electronics / Re: PECL/ECL Logic on: March 16, 2014, 07:46:03 am
As you say , PECL, is Positive referenced ECL

ECL is what you might consider up side down,
    a '1' in ECL is about -1v , and a '0' in ECL is about -2 volts.

This was done for noise reasons, as the ground is normally lower noise than the 'other' supply,
   
PECL changed this, so '1' is about 4 volts, '0' is about 3 volts .....

please check the data sheet of the source as to what you have.

PECL is normally used in devices that are expecting to be 'fast' , so surprising to see in an opto sencor.
    if its driving over any distance, its best to use a PECL to TTL translator chip, 
         such as these http://www.onsemi.com/PowerSolutions/product.do?id=MC100ELT21

You can get away with circuits, such as if you are only detecting a change, then a capacitor can be used in series to generate a TTL spike the arduino can see,

What sort of speed you lookign at ?

4  Using Arduino / Motors, Mechanics, and Power / Re: High level switching with PNP darlington on: February 15, 2014, 07:05:54 am
looks good for an input,

I prefer to see switch on the high side of the opto, not the low side,
     so when switch open, no 12 volts on the board,
         ( you open the switches to work on the arduino and short something it goes bang )

you dont need to join the grounds at the opto,
    the right and left sides are isolated,
        provided the led in the opt lights , the opto works,
       
btw : check that 300 ohm value, the opto is only going to need a few mA, check the data sheet the resistor might be a bit low.



as for outputs, I cant remeber what your using ,sorry

   
5  Using Arduino / Motors, Mechanics, and Power / Re: High level switching with PNP darlington on: February 12, 2014, 03:00:08 pm
we'd all love a ruged arduino mega, but thats not going to happen now.

great to see the board, it looks good.

do your leds have built in current limiting resistors ?
   
6  Development / Suggestions for the Arduino Project / Re: ESD Safety on: January 29, 2014, 03:51:36 pm
As an aside,

I once worked for a company when ESD started becoming a concern.

the stores team were told all electrical stuff was ESD sensitive, so they spent a fortune earthing and lining all the draws with a nice metal shield ( tin foil to you and me ).

It took us a while to work out why the new AA batteries from stores always seemed to be flat !!!


7  Using Arduino / Motors, Mechanics, and Power / Re: Controlling a Satellite Motor DisEqC on: January 12, 2014, 02:19:21 pm
DisEqc,
   If I remember , modulates the 12 volts power supply to send serial commands to the dish, motor and the LNB.
        something like 11 volts to 14 volts, to make 1's and zeros'

the trick is the cable also caries the satellite signal as well,
     multi use of the single core cable,

is this of use

http://www.boards.ie/vbulletin/showthread.php?p=83715209


8  Development / Other Hardware Development / Re: How long can my arduino work continuosly? on: December 16, 2013, 03:26:25 am
totaly agree

the actual board is not the limiting factor in how long an arduino can work continuously,



9  Development / Other Hardware Development / Re: How long can my arduino work continuosly? on: December 15, 2013, 11:39:59 am
Agree

A random crash is normally the constraint on how long a processor will run,
 
U just need to decide how you cope with said event happening, no matter what the cause was.
10  Development / Other Hardware Development / Re: How long can my arduino work continuosly? on: December 15, 2013, 05:03:19 am
it does happen
   it is a problem

how oftern has one had to reset a computer, your tv gone 'silly' or the washing machine gone funny,
   I bet every one who has a few micros around the house has had a few funnies over the years.

if it does not matter to your design, then your ok,
    but random none programmed behaviour can not be ignored,

if you decide a random crash is not a problem, then thats a good solution, most arduinos I would suggest are like this. if it goes wrong the user cycles the power,

ways to mitigate include,
  power  reset the processor regularly,
      have an external  watchdog timer that resets the processor if an error is detected,
     
there are many other harder and simpler methods, which might suit your application , but these two are a good starting point.

As an example,  I for one would not have a processor controlling a large motor without their being a limit system in place that kicks in if the arduino system for what ever reason goes wrong.

   
11  Development / Other Hardware Development / Re: How long can my arduino work continuosly? on: December 14, 2013, 08:03:26 am
there are two parts to this

electro / mechanical ,
   yep the thing should keep going for decades,
   
BUT:
   its a small bit of silicon, with a few electrons per bit in the program.
       one strike via a stray neutron , esd spike or what ever, and the program will glitch.
           now that glitch might be to some where that the program can recover,
                    or it might be to some where that causes the mirco to 'crash'.

and over years, the code will glitch at some point,
     

12  Using Arduino / Project Guidance / Re: Watchdog in Arduino Library - or at least support by bootloader on: November 20, 2013, 03:29:21 am
is it just me

or is it sad that the arduino team did not implement the one line fix


13  Using Arduino / Motors, Mechanics, and Power / Re: BIG Motor Control - Recommendations for 250in-lbs torque motors? - Video on: November 12, 2013, 03:12:40 pm
if your happy with that motor / gear box stay with it.

switch it on / off in pulses to control the speed,
   the 90 degree gear box should stop back lash / movement, my guess is it has a worm gear in it.

14  Using Arduino / Motors, Mechanics, and Power / Re: Using MOSFETs versus Darlington Transistors. on: November 12, 2013, 03:06:55 pm
just go for a opto isolated circuit with a mosfet for the current.
15  Using Arduino / Networking, Protocols, and Devices / Re: Ethernet shield server test (last day) on: November 06, 2013, 01:59:37 pm
very nice,

can see the web pages here just fine,
   using chrome.

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