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1  Using Arduino / General Electronics / Re: Arduino Due + LED Resistor Requirements on: Today at 06:43:38 pm
The due has the least voltage/current vs say an uno eg 3.3v vs 5v

So you're not going to get very brightly lit LED's are you using 5mm uv leds or more powerful ones?
2  Using Arduino / General Electronics / Re: arduino-18650 charger-help. on: Today at 06:38:54 pm
You wish to charge the connected batteries to arduino?

Except, you require > 8v  to charge 2 batteries in series, and then it becomes tricky, charging 2 individual batteties via 5v is the easier option.
3  Using Arduino / Project Guidance / Re: Using LDR as a alert at anytime during program on: Today at 12:15:09 am
I don't unde and how you mean you can send it once?

Why not call xively before the twitter post? The code I understand but the system ie how to post tweets, what are the steps involved!
4  Using Arduino / Project Guidance / Re: Car power supplying Arduino?? on: Today at 12:04:14 am
The car has a average voltage of 14.4vdc, and will not start below 13vdc. 



Average voltage is 14.4v is it?
Car refuses to start under 13v

And who took these measurements?   Average voltage from the alternator is around 14v the car would have issues if the battery read 11.5v (starting it) but 12.5v to 13v is plenty to turn the starter motor...

 your values seem off.
5  Using Arduino / General Electronics / Re: What areas of electronics are useful to learn about for arduino projects? on: July 23, 2014, 12:29:44 pm
I once had a teacher/supervisor who grumbled on about how students now just use an mc to do the work over the use of good old logicchips...

I guess it boils down to what you want to do, no point learning about low pass filters if all you want to do us blink an led and make it go beep
6  Using Arduino / General Electronics / Re: Wind generator for 12v battery - no controller? on: July 23, 2014, 11:17:15 am
The turbine can supply peaks higher than 14.5v but the current is lacking to do any real damage. Since the motors rated for lead acid it will produce aroind 14-18v with a light load, but the battery will suck up the current and not go over, unless it happens to produce stupid amounts for current/voltage..

People use 240vdc rectified and fed into 12v batteries to "regenerate" them... as long as it does not boil and run out of water/acid it's practically happy

But sticking a 14.5v switching regulator on the output is the best way for a lead acid.

7  Using Arduino / General Electronics / Re: can this led be powered off arduino digital pin? on: July 23, 2014, 11:10:15 am
Awol is correct  but he forgot to add up to 40 ma with current limiting or you will kill your pin.
No, he didn't forget - that's what "up to the pin's absolute maximum current of 40mA" means - the current limit is implicit.

The pin will max out and supply possibly higher current than that for a while.
8  Using Arduino / General Electronics / Re: 110V detection on: July 23, 2014, 11:08:36 am
I'm trying to find an solution that is easy to implement for my problem.

I'm using arduinos to control 5V/10A relays to switch on and off lights, plugs and heaters.
For the lights, the relay has all the 3 wires connected, so you can use it with the wall switch too.

I would like to detect via the arduino if the light is on or off, because the arduino knows the state of the relay, but not the state of the wall switch, and to call a light on or light off command would require to detect if the light is on or off.

I tried at first with a current sensor: ACS714. I don't want to measure the amount of current but just to tell if the current is on or off.
My problem is that since I use LED lights, they seem to have a too much low current consumption: 5W, 45mA, so between power on and power off, I see no difference in my readings. I calculate the average current in a 50ms delay.

My code is the following:
boolean isLightOn(int analogPin) {
  int count = 0;
  float currentSum = 0.0;
  int counter = 50;
  while (count < counter) {
    currentSum += abs(analogRead(analogPin)-510);
  return (abs((currentSum/counter)) > 3);

Does anyone have an idea on my problem ?
Is my assumption correct ?
Is there another option to detect if the power is on or off ?

My first thought is an opamp, as a comparitor so you get back a high/low signal using a pot to fine tune.
9  Using Arduino / General Electronics / Re: can this led be powered off arduino digital pin? on: July 23, 2014, 10:55:37 am
Awol is correct  but he forgot to add up to 40 ma with current limiting or you will kill your pin.
10  Using Arduino / Networking, Protocols, and Devices / Re: Trouble with both DS1307 and DS3231 RTCs and time slowing down on: July 22, 2014, 02:35:00 am
wb Nick  smiley  seems you're stiring up some fuss  in another thread lol
11  Using Arduino / General Electronics / Re: bad design? on: July 21, 2014, 10:33:54 am
Similar?  It's not supposed to be...

If I created a 10mv peak to peak, the first circuit fails!  (Back to working out how much voltage /can/ be produced from say a remote control .

Speed is not an issue, amplifying it without an opamp was hence my circuit (2nd circuit)
12  Using Arduino / General Electronics / Re: Yet another LP2985 voltage regulator problem on: July 21, 2014, 10:18:04 am
Replace or use a different regulator?
13  Using Arduino / General Electronics / Re: bad design? on: July 21, 2014, 09:07:13 am
The first circuit is just an IR detector. It just lights an LED in the presence of sufficient IR, no matter what it is.

The circuit you simulated is nothing like it. So I'm not sure it proves anything.

But does it really? (Waiting on the ir receiver diodes) how much voltage is produced from an IR strike?
14  Using Arduino / General Electronics / Re: bad design? on: July 21, 2014, 08:57:59 am
I will..... just curious .
15  Using Arduino / General Electronics / Re: Temperature coefficient diodes. on: July 21, 2014, 07:39:15 am
I'm basically using the zener's reverse foward voltage drop to counter out diodes foward voltage drop.... so the voltage stays relatively stable.. pointless I know more curious in the way diodes are exploited like this even being used as a temp sensor (normal diode with a tiny current measuring the foward voltage drop)

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