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496  Using Arduino / LEDs and Multiplexing / Re: fading a light on: March 26, 2011, 01:05:58 pm
I was on pin 12
Too bad all problems aren't that simple!
497  Using Arduino / LEDs and Multiplexing / fading a light on: March 26, 2011, 11:37:56 am
Can someone please tell me what IC to use to fade this:

...I've tried using the mosfet:
...but it doesn't fade, it just is either ON or OFF

I've searched for fading, but find thousands of topics.  If someone could just tell me what chip I need, I can search it out.
498  Using Arduino / Displays / Using Pin 13 for LCD on: March 26, 2011, 01:51:17 am
Will there be any unforeseen problems using pin 13 (that has the built in LED) to operate my 2x16 LCD display's pin 6 (H/L Enable signal)?
499  Using Arduino / Displays / Quick urgent PWM question on: March 25, 2011, 10:59:15 am
I'm wanting to fade Spakfun's 16x2 LCD display.  the specs are:
LED forward voltage  4.2   (4.6 V max)
forward current 120    (160 mA  max)

I had it prototyped on my board through a 100 ohm resistor off a PWM pin from the Uno and it seemed to fade in and out okay, but for 120 mA, shouldn't I have a transistor drive it or something, since the I/O pins are limited at 40ma?
I have the backlight negative connected to ground, the positive goes through the 100 ohm resisitor to a jumper that I can switch from either 5+, or to the D0 pin. With this config. what transisitor & bais resistor would I need coming off the D0 pin?
If someone could recommend what transistor to use, I don't understand them all together yet.  Not sure if I need a PNP or a NPN for this type of config.  I have a lot of common transistors, just don't know which one I need to use here.
500  Using Arduino / Motors, Mechanics, and Power / Re: Using the SN754410 on the adafruit motor sheild on: March 24, 2011, 09:05:09 pm
Okay, I will incorporate them in then.  Some 1N4005's are laying around here.
501  Using Arduino / Motors, Mechanics, and Power / Re: Using the SN754410 on the adafruit motor sheild on: March 24, 2011, 09:00:48 pm
Thanks.  I think I'll 'risk' it then without them.
502  Using Arduino / Motors, Mechanics, and Power / Using the SN754410 on the adafruit motor sheild on: March 22, 2011, 10:40:40 pm
On using the SN754410: Some people use the SN754410 motor driver chip because it is pin-compatible, has output diodes and can provide 1A per motor, 2A peak. After careful reading of the datasheet and discussion with TI tech support and power engineers it appears that the output diodes were designed for ESD protection only and that using them as kickback-protection is a hack and not guaranteed for performance. For that reason the kit does not come with the SN754410 and instead uses the L293D with integrated kickback-protection diodes. If you're willing to risk it, and need the extra currrent, feel free to buy SN754410's and replace the provided chips

What if I add my own flyback diodes (1N4007), would it then be perfectly safe to use the SN754410?
But is it possible to add these diodes to the circuit and still maintain a reversible motor?
503  Using Arduino / LEDs and Multiplexing / Re: Controlling 2-4 LED's on: March 16, 2011, 05:05:05 pm
I guess I won't really need the high power LEDs.  Here's what I plan to use:

...I shouldn't need anything but the RFP30N06LE MOSFET to use this since my power supply is 12 volt and it is made to connect to automotive 12 V.
504  Using Arduino / LEDs and Multiplexing / Re: Controlling 2-4 LED's on: March 16, 2011, 08:14:32 am
I wouldn't use resistors on high power LEDs, you need constant current drivers to make it safe and reliable.
???  You can't just use resistors to drop 12 volts or 5 volts down to the proper voltage for high power LED's.  'Constant current drivers?'  Is there some good reading you'd recommend to better understand this?  I'm wanting 1-4 LED's to kind of light up an area under a cabinet.  Not sure how big of LED's I need.  There's 'super bright' LED's, but I don't think they really use that much current.  Does anyone have any good info on this topic?

ps.  would something like this not work with just some resistors...
505  Using Arduino / LEDs and Multiplexing / Controlling 2-4 LED's on: March 14, 2011, 09:41:37 am
Would this RFP30N06LE MOSFET work for turning 2-4 LED's in series or parallel  on/off with 1 pin?
506  Using Arduino / Audio / Re: Using the Tone() function on: March 13, 2011, 05:40:37 pm
Thanks, I shouldn't have a problem, then.
507  Using Arduino / Audio / Using the Tone() function on: March 12, 2011, 08:01:33 pm
I am planning to use the Tone() function to give a short 5 note melody when an event is finished.  At the time I play the melody, there won't be anything else happening in my code.  But at other times my code DOES use millis() and PWM.  Are millis() and PWM only affected at the actual time I'm using the Tone() fucntion, or all the time? 

ATmega8: 2 (timers 2, and 1)
ATmega168/328: 3 (timers 2, 1, and 0)
ATmega1280: 6 (timers 2, 3, 4, 5, 1, 0)
The timer order given above is the order in which the timers are allocated. Timer 0 is a sensitive timer on the Arduino since it provides millis() and PWM functionality
508  Using Arduino / Displays / Re: shiftreg alternate IC on: March 12, 2011, 05:04:39 pm
I ended up using this to get my LCD working with the  SRLCD library and that SparkFun IC, 74HC595.,15364.msg112755.html#msg112755
509  Using Arduino / General Electronics / Re: vias on homemade pcb on: March 10, 2011, 11:03:41 am
Ah yeah, the best idea may be not to do the plated through hole at all, but just put a via right next to the IC when needed.
510  Using Arduino / General Electronics / vias on homemade pcb on: March 10, 2011, 09:04:44 am
Using an IC socket is a nightmare when traces are on the top side of the board, under the IC and you try to use a socket. I read this:
or buy the little pins made for the purpose (called 'vias')
...but have searched and searched to buy something called vias and can't find anything.  Is there such a thing?
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