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721  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...
722  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
723  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
724  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.
725  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..

726  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...

727  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.
728  Using Arduino / LEDs and Multiplexing / Re: Help me select 5mm LED's for SSD used in sunlight please on: December 08, 2013, 04:27:59 am
What power source you using?

(Not just usb power? :o)
729  Using Arduino / Project Guidance / Re: Completely new- please steer me in the right direction. on: December 08, 2013, 04:25:13 am
An uno for sure....

You could go to your electronics store buy several of the most common resistors, breadboard, leds..

Resistors sizes ... 1k, 300ohm, 10k, 100k resistors.
 
Get several pnp, npn transistors, a couple of capacitors.. 1uf 0.1uf either ceramic or electrolytic.

And you're good to go for the basics,  but... that really is the essentials kinda like salt, pepper, your basic condiments to make the meal complete, from this point on you really have to buy components for what you need rather than want because you'll end up stock piling components which is fine but storage space quickly vanishes lol.

Then you can think about potentiometers, regulators, diodes etc... there's a lot to get your head around but take it slow and try all the examples with Arduino blink, no delay, tone ..
 

A piezo speaker not essential but handy.

Bottom line... source your parts first, get spares if you can.


730  Using Arduino / Project Guidance / Re: Another smoking Leonardo on: December 08, 2013, 04:06:49 am
I'd never use 12v on an Arduino unless the load is very light, otherwise the linear regulator will turn into a stove.

To keep heat down, supply 7v to the dc barrel, and stick to low current, anything over 30ma use a transistor to power your loads (unless you need more power, fets, relays/triac etc...

My concern is that the atmega fried..

I'll be honest I always use a 7805 (from a 12v supply) and feed it directly in, I'm yet to see that setup fail... but this is the catch the real arduino board should have been fine, the cheap clones use some el cheapo chinese regulator which is useless for any decent amount of current.

731  Using Arduino / Project Guidance / Re: Pir to to turn simple motor on and off. . on: December 07, 2013, 08:11:56 pm
as simple as using a transistor on a digital out pin,  (digitalWrite, delay(1000); digitalWrite)
732  Using Arduino / Project Guidance / Re: Another smoking Leonardo on: December 07, 2013, 07:14:40 pm
it could be the regulator, hopefully it burnt out protecting the rest of the board..

take a picture?
733  Using Arduino / Programming Questions / Re: Android phone always charges when connected by USB on: December 07, 2013, 08:01:54 am
snip the powerlines and leave the data lines free?...

unless there's some kind of check to make sure there's power, it should work.?
734  Using Arduino / General Electronics / Re: GPRS Shield Blew up on: December 07, 2013, 06:40:27 am
You sure it's a cap? looks like a Schottky diode to me...



735  Using Arduino / General Electronics / Re: fet vs bipolar transistors... on: December 07, 2013, 06:33:39 am


someone posted that (about a fuse)

and I was thinking, why a fet?...
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