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871  Using Arduino / General Electronics / Re: fet vs bipolar transistors... on: December 08, 2013, 07:43:53 am
Is that the purpose of the diode in series with the red led? To prevent red from taking the green led's juice?

872  Using Arduino / Project Guidance / Re: Which language should I learn? on: December 08, 2013, 07:33:40 am
To stop duplicates simply store the last read id code and  make sure they're not the same...

Eg

If (oldid!=newID)
  ......;

873  Using Arduino / Project Guidance / Re: Which language should I learn? on: December 08, 2013, 07:30:11 am
Apps are widely written in Java, so try the program Eclipse. More direct, look at Android App Developers + Eclipse.
Keep in mind, Java is not that easy.

If I was religious. ...

Java was developed by satan lol...

But yes get the adt bundle, you can use bluetooth or wifi (ethernet shield on an uno) bluetooth uses 2 pins for uart while spi requires a few more pins, the nrfl whatever uses spi then you have to individually address each slave....

Swings and roundabouts.
874  Using Arduino / LEDs and Multiplexing / Re: I can't power a laser properly:( help me? on: December 08, 2013, 07:24:34 am
Question... when it begins to dim, cool the regulator down does the laser come back to life?

To cool it down, place an ice cube into a clear leakproof bag and rest it against the regulator or if you have freeze spray use that.. where does the problem lay?
875  Using Arduino / General Electronics / Re: MOSFET questions on: December 08, 2013, 07:15:19 am
A thermistor can't be connected to the MOSFET, now can it.. smiley


On top of it... sure.
Using the thermistor with a voltage divider to the gate of the fet... it could be

I was thinking of it to measure the radiator. ..
876  Using Arduino / General Electronics / Re: fet vs bipolar transistors... on: December 08, 2013, 07:12:38 am
http://www.talkingelectronics.com/projects/200TrCcts/images/BlownFuse.gif


But.. it's constantly powering 2 leds (until the fuse blows), am I really considering This with a bjt?..... well yes I am lol... I'll submit my entry soon smiley
877  Using Arduino / Project Guidance / Re: Completely new- please steer me in the right direction. on: December 08, 2013, 07:06:21 am
Regarding the 2 lined lcd units..

Pick i2c versions and spend the extra 5 bucks....  5 bucks more equates to 5 hours less time spent making it work smiley
878  Using Arduino / Project Guidance / Re: Another smoking Leonardo on: December 08, 2013, 07:03:23 am
Nick!

That alarm clock is exactly why apps for mobile devices are used... even though this is 1000x easier than using ic counters and logic chips smiley

(P.s love the alarm clock)
879  Using Arduino / General Electronics / Re: attiny in car delay then send a 12v pulse on: December 08, 2013, 05:17:55 am
An attiny makes it too easy smiley

Use a resistor divider to split the 12v signal to say 4v for a logic high, when you see it, delay (4000);  then digitalwrite to a transistor to send the 12v signal back...
880  Using Arduino / General Electronics / Re: MOSFET questions on: December 08, 2013, 05:12:39 am
Yeah a simple ntc thermistor would do the job smiley
881  Using Arduino / LEDs and Multiplexing / Re: I can't power a laser properly:( help me? on: December 08, 2013, 05:02:52 am
Use a higher voltage then, then feel the driver board see if its getting warm, hot if it is ... it wont last
882  Using Arduino / General Electronics / Re: MOSFET questions on: December 08, 2013, 04:59:49 am
If it fails you simply need to be lucky lol

How much power is being disapaited ? I was thinking maybe a sense resistor to determine if the fet is still behaving, by enabling, disabling you can measure the voltage drop via a sense resistor and if nothing changes signal a warning.
883  Using Arduino / LEDs and Multiplexing / Re: I can't power a laser properly:( help me? on: December 08, 2013, 04:50:13 am
Oops after all that!

The driver for the laser is connected! How easy do you want it, connect 3v up and away you go!  Lm317 or a 3v reg of your choice..

884  Using Arduino / LEDs and Multiplexing / Re: I can't power a laser properly:( help me? on: December 08, 2013, 04:44:21 am
Take a voltage reading...

Eg 5v
Lets say you want 10ma of power. (5v @ 0.01 amps or 0.05watts)

5 - 2 (foward laser diode drop)
3 / 0.01

You'd require a 300ohm resistor...

885  Using Arduino / LEDs and Multiplexing / Re: I can't power a laser properly:( help me? on: December 08, 2013, 04:30:26 am
So I'm trying to make a laser trip switch, everything works besides my laser:( its a 50mW green laser that uses 2 1.5V AAA batteries. I took the batteries out and I'm trying to power it with a 12v battery working trough a 5v regulator with a few diodes in series to bring the volts down to 3v. I connected a 20ohm resister after the diodes to limit current but it doesn't even turn on. I then connected a 10ohm resister (10 parallel 100ohm registers) and then the laser comes on but goes dimmer and dimmer after about 30seconds or so. Why does it do this and how can I properly power it without using batteries. I did not remove the laser driver

Dimmer and dimmer...

RIP laser diode.

(You put too much current through it, best you'll get is a dim glow now)

With a working diode you need to calculate how much current to supply using ohms law.
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