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1  Using Arduino / General Electronics / Re: Arduino AC Voltage Dimmer (Variable Resistor? PWM?) on: August 21, 2014, 08:09:48 pm
It could run on 65V DC, too.
What's your 65V AC source?

If you need VAC then you need a Triac.

You could use a 120/220v transformer, put 120 into the 220 side and get 60 or so out.
2  Using Arduino / Motors, Mechanics, and Power / Re: Power an e300 Electric Razor Scooter from an AC Source? on: August 20, 2014, 08:00:43 pm
A slip ring (or a heavy-duty slip ring.)
3  Using Arduino / Project Guidance / Re: Want to make a digital clock with Arduino Uno & 7 segment Led Display on: August 19, 2014, 09:34:57 pm
CrossRoads came up with this clock sketch that I modified for 24-hour.
It uses Serial Monitor, but it should be easy enough to knock out the numbers as segments, etc. using shift registers or a 7219 routine instead.

Code:
/* 
    CrossRoads Timeclock 
    Adapted for 24hr time
    by Me!  08SEPT2012
    __h__m__s
    and leading zeros, too
*/

unsigned long previousTime = 0;
byte seconds ;
byte minutes ;
byte hours ;

void setup()
{
  //  Preset HHMMSS for 24hr rollover test
  //  Could jump to a function to set time
  //  and start
  seconds = 45;
  minutes =  59;
  hours =  23;
  Serial.begin (9600);
}

void loop ()
{
// I wonder whether "microseconds"...
  if (millis() >= (previousTime))
  {
     previousTime = previousTime + 1000;  // use 100000 for uS
     seconds = seconds +1;
     if (seconds == 60)
     {
        seconds = 0;
        minutes = minutes +1;
     }
     if (minutes == 60)
     {
        minutes = 0;
        hours = hours +1;
     }
     if (hours == 24)
     {
       hours = 0;
     }
     if (hours < 10)
     {
       Serial.print("0");
     }
     Serial.print (hours, DEC);
     Serial.print ("h");
     if (minutes < 10)
     {
       Serial.print("0");
     }
     Serial.print (minutes,DEC);
     Serial.print ("m");
     if (seconds < 10)
     {
       Serial.print("0");
     }
     Serial.print(seconds,DEC);
     Serial.println("s");
  } // end 1 second
} // end loop

You might even say that it's deceptively accurate.
4  Using Arduino / Motors, Mechanics, and Power / Re: dc motors without arduino motor shield on: August 18, 2014, 07:57:23 pm
Here is a picture of a kit with the (right) idea

5  Using Arduino / Motors, Mechanics, and Power / Re: dc motors without arduino motor shield on: August 17, 2014, 11:45:02 am
...and there's your lone 9V transistor battery.
That just is not going to make it.
You have to fabricate a battery pack.
Like a 6 X AA [for 9V] or two 4 X AA packs for 12V. 
Anyway, something substantial, as others have called out.
6  Using Arduino / General Electronics / Re: Why are there so many more N-Channel Fets available then P-Channel? on: August 17, 2014, 10:45:17 am
It's easy to  get trapped in, locked into, this "HI/1/+V == ON" paradigm.
7  Using Arduino / Motors, Mechanics, and Power / Re: dc motors without arduino motor shield on: August 17, 2014, 08:43:59 am
also is it ok to upload photos via photobucket so tha you can see them easily?
please help....

Yes, I use photobucket.
Get the direct link to the picture and place it in your post between IMG tags, à la
[img]photobucket link[/img]
8  Using Arduino / General Electronics / Re: How to use a DAC0808 with the arduino on: August 16, 2014, 01:28:06 pm
What exactly is the simplest DAC you can come by that's easy to use?
.... my purpose.

simplest --
see R-2R resistor ladder network (digital to analog conversion, or DAC)
http://en.wikipedia.org/wiki/Resistor_ladder
-------
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/dac.html
http://www.tek.com/blog/tutorial-digital-analog-conversion-%E2%80%93-r-2r-dac
http://www.irctt.com/pdf/LADDERNETWORKS.pdf

Anyway, you only get something for nothing on "Instructables".
9  Using Arduino / General Electronics / Re: How to get an output voltage of 9V from arduino uno?name some ic's for it. on: August 16, 2014, 11:33:44 am
http://forum.arduino.cc/index.php?topic=261322.0
10  Using Arduino / General Electronics / Re: How to get an output voltage of 9V from arduino uno?name some ic's for it. on: August 16, 2014, 11:32:52 am
Boost converter (boost regulator), et al.
11  Using Arduino / General Electronics / Re: Does a LM7809 help me boost arduino uno's 5V to 9V? on: August 16, 2014, 11:31:39 am
Not.
12  Using Arduino / General Electronics / Re: How to use a DAC0808 with the arduino on: August 16, 2014, 11:15:29 am
I'm not good with the DAC IC's VEE being at 0V/Gnd (missed that) either.

I vouch for my design shown.
13  Using Arduino / General Electronics / Re: How to use a DAC0808 with the arduino on: August 16, 2014, 11:08:36 am
The op-amp is configured as a transconductance amplifier, a current-to-voltage converter.

since i'm hoping to just use it with an arduino and without an extra power supply, i was glad to find the above diagram that simply uses it with 0 and 5V, but could that be the issue?

Two 9V transistor batteries make a dandy dual-ended supply.
In fact, you could "get by" with one for the negative supply (so you'd have a +5/-9V supply, big whip.)
Then decide what you want to do going forward (excuse the biz-speak.)
14  Using Arduino / General Electronics / Re: How to use a DAC0808 with the arduino on: August 16, 2014, 10:33:05 am
But when i wire it up like that... it does absolutely nothing.

Having to ask, since I don't know your skill-set like, but the dwg doesn't show the op-amp's power pins.
So, in case you did exactly what's shown and nothing more...
Do you have the op-amp's power pins connected (to anything)?

> > > adding dwg of my own
15  Using Arduino / Motors, Mechanics, and Power / Re: Power an e300 Electric Razor Scooter from an AC Source? on: August 16, 2014, 09:03:20 am
Fabricate your own connector to the scooter battery, a "lead out", so you could disconnect it from the scooter and connect it to your charger (which, evidently, you have already.)

molex, quick-ons, etc

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