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961  Using Arduino / Motors, Mechanics, and Power / Re: Stepper motors turning X degrees wth a push button. How to do it? on: May 04, 2013, 07:24:13 am
Only an open cholecystectomy can be had for free on a forum (I think everyone knows that.)

Back to the subject at hand --
http://www.tigoe.com/pcomp/code/circuits/motors/stepper-motors/
962  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 04, 2013, 06:56:32 am
Glory!
963  Topics / Interactive Art / Re: RGB LED issues HELP on: May 03, 2013, 09:44:54 pm
There are Common Anode RGBs and Common Cathode RGBs.
964  Using Arduino / Motors, Mechanics, and Power / Re: Constant Voltage and Amperage to Motor Controller on: May 03, 2013, 09:40:08 pm
Tonight, the "secret word" is: encoder.
965  Using Arduino / General Electronics / Re: AC Dimmer circuit ideas on: May 03, 2013, 09:17:03 pm
(1) Arduino PWM could be RC'ed into a "stable" DC
(2) Zero_Cross could be RC'ed into a sawtooth

(1) Is the adjustable threshold voltage of a comparator (inverting input)
(2) Is the trigger voltage of a comparator (non-inverting input)
The comparator output is low till (2) > (1)
The output will go HI quicker, with respect to ZC, when threshold is closest to Gnd.

The comparator output is the trigger (low-to-hi transition) of a non-retriggerable multivibrator (74HC221).  The '221 output would go to the input of an opto-triac the output of which is connected to the TRIAC gate.
Just keep the pulse width narrow enough that it won't extend past the next ZC at max delay.
966  Using Arduino / Programming Questions / Re: analogRead with or without delay? on: May 03, 2013, 06:51:20 pm
OK, I guess, so why not drop the other shoe, mate?
967  Using Arduino / Motors, Mechanics, and Power / Re: Stepper motors turning X degrees wth a push button. How to do it? on: May 03, 2013, 06:48:33 pm
Step Angle is "usually" (ordinarily, typically) 1.8 deg.

If you go wave or 2 phase
8 state changes = 14.4 deg
9 state changes = 16.2 deg

If you half step then it's 0.9 deg / state change
17 state changes = 15.3 deg
968  Using Arduino / Programming Questions / Re: analogRead with or without delay? on: May 03, 2013, 06:37:45 pm
What does help a great deal is to insert a delay inside the analogRead code, between setting the multiplexer to the desired input channel and starting the conversion. A delay of 10us here allows use of inputs with up to 100kohms source resistance without loss of precision, and a delay of 100us works for up to 1Mohm (but expect some loss of accuracy in this case, since the ADC has a typical input resistance of 100Mohms). Adding a delay here is much more effective than the usual remedy of repeating the analogRead() call and discarding the first reading.

dc42,
Do you mean then to modify the analogRead( ) function itself?
[ If so - How? ]
969  Using Arduino / General Electronics / Re: I burned out my Nano with a 12V power supply... why? on: May 03, 2013, 10:46:21 am
The max in depends on the current demand from the on-board regulator.
If all that's going on is the Pin13 LED and some inputs, then 20V is "OK" (pushing the envelope).
But with any considerable outputting, tapping off the on-board 5V and so on, then stuff starts getting hot.

970  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 03, 2013, 07:42:58 am
Hopefully this solves the issues I was having initially w/ the analog input voltage being skewed once plugged into my bike.

The analog trouble's solution will be changing the source/"Vin" to 9V.
971  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 02, 2013, 08:23:23 pm
Get 100Ω (brown-black-brown) resistors - or my head will explode.

"How can I test that the resistors are working?"
The only way to KNOW is with a voltmeter.
+5 to CA, one lead of one resistor to any segment (cathode) with the other lead to Gnd.
There will be approx 1.5V across that resistor.

If the "spare" LED is a blue LED, you can use that.
If the "spare" LED is another colour then it will have a different forward voltage and skew the results.
972  Using Arduino / General Electronics / Re: Can my Arduino burn up if my voltage regulator overheats? on: May 02, 2013, 07:59:34 pm
I am using something like the LM317.  Its a three pin 9V regulator.  I think its a LM7809CT.  I'm not 100% sure though.  I have it hooked up through the input jack.  My arduino originally came with a 9V battery pack to power the arduino so could someone explain to me why that would work but the voltage regulator could possibly burn up the arduino???

In theory, it ought to be OK.
But statements like "I am using something like the LM317.  Its a three pin 9V regulator.  I think its a LM7809CT.  I'm not 100% sure though" don't make me want to leap up and shout, "Yes, Do It!" 
973  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 02, 2013, 07:36:14 pm
You have to connect the CA to +5, and NO, doing so will NOT "overvolt and damage them" - unless you don't use a resistor!
When the LED is ON it's its forward voltage is "3.5V"
So, the balance of the 5V will be across the resistor - 1.5V
That 1.5V across the resistor will determine the LED current
1.5V / 100Ω = 15mA

> > > I spelled all of that out in Reply#37.  You're not reading.


974  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 02, 2013, 06:29:34 pm
Grumpy_Mike,
pcguru has an Uno (it's there in his big darned PNG), there's 5V available on it - which I noted in my Reply_#37: "Anyway, you should have the CA wired to +5."
He was putting the 7-segment's CA to 3V in the belief, howbeit mistaken, that that would obviate any need for resistors.

975  Using Arduino / Project Guidance / Re: analog input alters voltage... doesn't read properly on: May 02, 2013, 07:58:18 am
So you project needs to be even more complex than just adding a resistor, you need a boost constant current LED driver.

Absurd.
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