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421  Using Arduino / Project Guidance / Re: trust a power supply? on: December 22, 2013, 02:56:04 am
There's an onboard regulator which converts the 12v to 5v

So less voltage (7v ideally) is better, what's the current rating? 12v how many milliamps?

422  Using Arduino / Project Guidance / Re: Faster better avrs on: December 18, 2013, 11:44:07 pm
You including the due?
423  Using Arduino / Audio / Re: A Microcontroller Amplifer (theory) on: December 18, 2013, 11:25:29 pm
Attiny85 amplifier...

The plan to read the voltage level and then amplify the waveform via a transistor (so only 1 input, and probably a pwm pin to bias the transistor)

No sampling, all basic stuff...
424  Using Arduino / Audio / A Microcontroller Amplifer (theory) on: December 18, 2013, 09:08:33 pm
Is it as simple as feed in  a signal and amplify the analog signal based on your analog value?... a bjt should be fine?  A fet?
425  Using Arduino / Programming Questions / Re: What does the "?" and ":" do in this Code on: December 18, 2013, 05:50:44 am
If you wrote a simple if statement like:

if (val == 10) {
   x = 20;
} else {
   x = 15;
You could write the same code using the ternary operator as:

x = (val == 10) ? 20 : 15;

If the conditional expression (val == 10) is True, the expression following the question mark is evaluated. If the conditional expression is False, the expression following the colon is evaluated.

This is where I'd have gone ...

"No, Mr Engineer Sir.... NO NO NO NO NO NOOOOOO"

if (x ==10) {?=20 else 15};

would make more sense...
426  Using Arduino / General Electronics / Re: I can't do hardware debouncing (i.e. for a button push) using a capacitor on: December 17, 2013, 11:43:09 pm
Both Americans and English And Australians and the Canadians speak English...

So why do so many translations between these countries go wrong?   we all speak English yet there's words that don't even exist in other countries..

I think this is all boils down to really,  it's all still the same language when it boils down...
427  Using Arduino / Project Guidance / Re: Paranormal Investigation Equipment on: December 17, 2013, 02:56:14 am
An emf meter.... a couple of transistors and an led lol
428  Using Arduino / General Electronics / Re: Trouble with a 7805 regulator. on: December 16, 2013, 06:34:26 pm
4.6V from a 5V regulator?
Either that is a very poor quality regulator or you don't have enough voltage on the input.
You can always "bump" up the voltage a bit by placing a diode on the ground pin of the regulator as long as the heatsink is not connected to ground.

See below.


Are you sure your servo is not drawing too much current (in excess of 1A) and overloading the regulator?
Did you measure the 4.6V with or without the servo connected?

I've only ever got 4.6~4.7v from all my 0805 regulators....

You could use a voltage divider (resistor & potentiometer) to tweak it if you need an accurate voltage.
429  Community / Bar Sport / 123D circuit emulator (Autodesk) on: December 16, 2013, 09:53:26 am

I have no clue at all wherd this thread should belong!

After googling for "new circuits 2013" outof boredom I come across that! Anyone tried it?
430  Community / Bar Sport / off planet robot wars! on: December 16, 2013, 09:16:10 am
 After seeing china's rabbit robot on the lunar surface...

I could not help but think about robots fighting up there, the next robot NASA sends up they better equip it with an axe or chainsaw incase a russian or chinese robot starts attacking it!  I'd pay to see off world robot fights smiley-grin
431  Using Arduino / General Electronics / Re: make use of wasted voltage? on: December 16, 2013, 08:37:07 am

Your best option is to reduce the voltage to the regulator..

Maybe pwm could be used to reduce wasted current (a 555 or Arduino etc).

Or simply use a switch mode power supply.
432  Using Arduino / General Electronics / Re: Basic circuit with temp sensor on: December 16, 2013, 08:30:04 am
As he said... the transistor will not snap on/off.

You have a couple of options, use an IC with a schmitt trigger (eg a not gate, nand, and etc)

But I'd not bother, grab another transistor tie the emitters together to gnd via a 1k or so resistor and create a schmitt transistor circuit, this will ensure a clean transition.
433  Using Arduino / General Electronics / Re: I can't do hardware debouncing (i.e. for a button push) using a capacitor on: December 16, 2013, 08:17:03 am
Hah... I'm lazyer than all of you, with exception I use a pulldown/up resistor ..

DigitalRead.. if it's high, I use a 300ms delay (to make sure your finger is off)  unless it's time critical to hell with how it works  smiley-lol
434  Using Arduino / General Electronics / Re: my display lights some LED's very lightly and it should'nt do that on: December 16, 2013, 07:11:58 am
360 leds? 5mm? / 1watt?

Mosfets for 360 5mm leds.... how many fets? (What a waste)
435  Using Arduino / Project Guidance / Re: Power by batteries, charge when plugged in. on: December 16, 2013, 04:34:22 am
Yeah it is....

But how depends on what you have in mind, a step up dv dc converter msy be in order to charge batteries > 4.8v
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