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4291  Using Arduino / Project Guidance / Re: Small animated display with LCD and SD card? on: September 12, 2012, 09:28:00 pm
"Every few seconds" should be no problem.

This $40 2.8" device from adafruit includes a touch screen:
4292  Using Arduino / Motors, Mechanics, and Power / Re: Jst to jst connector on: September 12, 2012, 09:10:57 pm
The two devices are a LiPo charger and a boost regulator.

What I would do is:
    On the charger, put a JST connector.
    On the boost regulator, solder a JST jumper to Ground (-/black) and Charge In (+/Red).
    Plug that JST jumper into the charger.
    Plug the LiPo battery JST connector into the JST connector on the boost regulator.

Or maybe get both on one board:
4293  Using Arduino / Programming Questions / Re: Rotary Encoder Problem on: September 12, 2012, 08:50:38 pm
Note all the comments that says
//these pins can not be changed 2/3 are special pins

And note how you have the pins defined:
int encoderPin1 = 4;
int encoderPin2 = 3;

A and B should be connected to 2 and 3, not 3 and 4.
4294  Using Arduino / Motors, Mechanics, and Power / Re: Petty Coin Bank Design - Coin Dispenser. What should i use? on: September 12, 2012, 08:44:40 pm
If you HAVE to use a slider you can make it FAST with a solenoid or slow with a servo.

Another option is to put the hole in a disk and have a motor rotate the disk.  A notch on the side of the disk and a microswitch can be used to sense the stop position.
4295  Using Arduino / Project Guidance / Re: Cost Effective Proximity sensing on: September 12, 2012, 08:39:13 pm
I would like to place object 1 on the board. The grid/sensors would then send a message to the arduino that "an object" is on the board.
I would then place object 2, in a different location. The grid/sensor would send a message saying "another object" is on the board.

Ideally i'd like for it to sense if it is object 1 or 2. I know that would be more difficult though. I thought using an RFID reader below the board, then attaching an RFID tag to each object.

I think your best bet for that is a force sensor to weigh the board and the things on the board.  If "Thing 1" and "Thing 2" have different weights they could be detected if your weight measurement is accurate enough.  I doubt you'll get a lot of accuracy for $20.
4296  Using Arduino / Project Guidance / Re: Cost Effective Proximity sensing on: September 12, 2012, 06:23:47 pm
Are you looking to sense contact or sense contact from a particular object?  Sensing contact would probably best be done with a resistive touch-sensor or a weight sensor (force sensitive resistor).  RFID certainly won't give you contact information.

If you need to be able to identify a particular object that will be much harder.
4297  Using Arduino / Motors, Mechanics, and Power / Re: cordless drill pwm transistor pins on: September 12, 2012, 06:19:01 pm
GDS is Gate Drain Source, indicating a MOSFET.

Many MOSFETs that are not specifically for use with microcontrollers will need 10V on the Gate to turn on fully.

4298  Community / Gigs and Collaborations / Re: Work For Hire $$$ - 1 Proximity Sensor, 4 Stepper Motors, & 1 LCD on: September 12, 2012, 06:14:18 pm
Note that the stepper controller you specify can control "Up to 2 stepper motors (unipolar or bipolar) with single coil, double coil or interleaved stepping."  Perhaps you will want a shield that can control four. Or you could get external stepper drivers (not a shield) and run wires to them.

If your LCD does not have an I2C or other serial interface you will likely run out of pins.

You have not said anything about what data appears on the LCD.
4299  Using Arduino / LEDs and Multiplexing / Re: RGB LED STRIP programming question on: September 12, 2012, 05:48:00 pm
My mistake.  I was going off the end of the array.  Fixed above.
4300  Using Arduino / Displays / Re: LiquidCrystal library on: September 12, 2012, 05:42:19 pm
  lcd.print("    ");  //  Blank out the previous value with four spaces
4301  Using Arduino / General Electronics / Re: What's the purpose of these pull-up resistors? on: September 12, 2012, 07:50:40 am
Thanks for your response, it makes sense to me. Same applies for the pull-down probably resistors upon the IRF7314s drains, do you agree?

4302  Using Arduino / Motors, Mechanics, and Power / Re: RC car + Arduino help on: September 12, 2012, 07:44:56 am
Sounds like your motor isn't getting much current.  The 1K resistor in the base of the transistor is limiting the base current to 5 mA.  Try something around 200 Ohms to bring the current up to 25 mA.  That's still safe for the Arduino and should help make sure the transistor is fully ON.

See this article about using transistors as switches:
4303  Using Arduino / General Electronics / Re: What's the purpose of these pull-up resistors? on: September 12, 2012, 07:34:40 am
Perhaps they are more for the IRF7314 gate inputs than the 74HC138 outputs.  Maybe they keep the FETs turned off during power-up.
4304  Using Arduino / Networking, Protocols, and Devices / Re: Trouble with SPI DAC... on: September 12, 2012, 07:23:26 am
Could your bit order be backward?  That will mess with your bit patterns.
4305  Using Arduino / Networking, Protocols, and Devices / Re: outside of void loop on: September 12, 2012, 07:16:32 am
I suspect the problem is that the server has not responded before you reach this line:

Since the data has not arrived your read loop immediately exits.  Perhaps you should put in a delay before assuming that all of the characters have arrived.
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