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991  Using Arduino / General Electronics / Re: first pcb try on: January 23, 2013, 08:09:47 pm
RE Post # 26 Pin 8 is connected to the crystal loading capacitors.. Only there is no visible net label or a ground symbol. While the cad program (Fritzing) might connect the pin labeled ground on the IC to ground, the pin isn't labeled so you got exactly what you put down. If you label that net as ground and do a copper pour it will fix the issue.

Bob
992  Using Arduino / General Electronics / Re: Capacitor side on: January 23, 2013, 05:29:32 am
Actually Historically speaking they are polarized... a polyester film capacitor is two long parallel plates (ribbons but the idea is the same) and the polarity came from old tube days and to a point even today for capacitors of similar construction. The major exception being metalized layered monolythic caps.
The standard american symbol looks like this:  This end was considered the inside foil and therefore more susceptible to noise pickup  > -----|(-----   < and this end was commonly accepted as the 'ground' end or outside foil. "From the 1949 Radio Amateur Radio Handbook" Published by the ARRL.
{Edit RKJ}
Bob
993  Using Arduino / General Electronics / Re: Diode doubt on: January 23, 2013, 05:07:58 am
A relay operates by turning electrical power into a magnetic field that attracts an "Armature" that has or moves an electrical contact from one position to another.
When the power is released the magnetic field caused by the passage of the current through the relay coil is concerted back to a voltage of nearly equal energy but reversed polarity and it is this 'Back EMF" or "Inductive Kickback" that must be eliminated as it is not only unnecessary electrical noise but is very damaging to other semiconductors in circuit. The conductive properties of a silicon diode are used to "'Short Out" the reverse or back emf pulse.
The diode parallel diode (across the coil or 1.JPG) is connected such that it doesn't conduct normally, just when thew voltage across it is reversed.
The series diode (2.jpg) has the diode reversed in the drawing but if reversed conducts normally when the circuit is energized and an open circuit when the power is removed, workable but very poor engineering. Either method will work but 1.jpg is preferred as there is no loss across the diode and the back EMF pulse is dealt with by being damped or shorted by the diode. 
As Chagrin pointed out there are current restrictions on the individual Arduino pins and connecting any kind of inductive load to an Arduino is NOT ADVISED, even a speaker has a series resistor.   
{Edit RKJ}


Bob
994  Using Arduino / General Electronics / Re: Two 7805s on one source on: January 22, 2013, 11:29:18 am
The easiest solution is a .1 ohm resistor in each regulator output lead (called a ballast resistor). the second best has been mentioned but a diode cathode to ground and anode to the regulator ground will raise the output voltage by one diode drop. This will compensate for the series diode. There are also voltage regulators that are capable of more than 1 A. It is also possible to amplify the available current with a PNP 'wrapped' around the regulator. The benefit of this is that the regulator can both control the voltage and share in the load current. This can be done with a 78L05... Too.
 {Edit RKJ} But Lefty's idea is the best way to go.

Bob
995  Using Arduino / General Electronics / Re: Which water sensor to buy ? on: January 22, 2013, 11:08:52 am
The 'Usual" Float sensor is just that, a magnet embedded in styrofoam. It triggers a reed switch when high or low fluid level is detected. I  used them for liquid fertilizers, reservoir sensing and dual tanks of many different types..
Jack Christensen Was Spot on in his analysis of the sensing requirements including the lower tank warning sensor. The upper tank sensor could be one assembly with 2 reed switches, One for the upper shut off sensor and the other lower one for pump start
The lower 'supply' tank needs a fill sensor to warn of low water level.

Bob
996  Using Arduino / General Electronics / Re: Datasheet site on: January 22, 2013, 10:47:34 am
When it's an unknown part this is the First place I look... Then Google "It" If "it" isn't there.

Bob
997  Using Arduino / General Electronics / Re: first pcb try on: January 22, 2013, 03:40:40 am
@ OP A good "First Attempt" And I did that work from design to turnkey work for nearly 35 years.
@pwillard.. GREAT looking work, home made but not obviously so. There were no location marks on the individual boards for cutting and that was the only real giveaway.
Spot on constructive criticism too.
Bob
998  Products / Arduino Due / New UTFT Libray with Arduino ARM spport on: January 22, 2013, 03:24:00 am
I found this this morning: NEW UTFT 2.0 Library.
Released about 10:00 AM PST 1/21/2013, Has support for Arduino, Arduino ARM and ChipKit Uno and Max32.
Partial release notes:
2.0   21 Jan 2013  -   added support for Arduino Due and Arduino Leonardo
            added support for the "AquaLEDSource All in One Super Screw Shield" on chipKit Max32
            added support for more display modules
            fixed a bug in printNumF()
            optimized drawLine()
            optimized 16bit data transfer
            optimized some 8bit data transfer
            added option to use pre-defined RGB565 values with setColor(), setBackColor() and fillScr()
            added functions getColor(), getBackColor(), getFont(), getFontXsize() and getFontYsize()
            added 16 VGA standard colors as pre-defined color literal
            rearranged the manual to keep related functions grouped together

Bob
   
999  Using Arduino / Displays / Re: UTFT Ver 2.0 on: January 22, 2013, 03:15:52 am
http://www.henningkarlsen.com/electronics/library.php?id=51

Center of the Page. File size is 1,279.4KB, UTFT 1.0X is 649 KB

Bob
1000  Using Arduino / Displays / UTFT Ver 2.0 on: January 22, 2013, 02:18:37 am
I found this this morning: NEW UTFT 2.0 Library.
Released about 10:00 AM PST 1/21/2013, Has support for Arduino, Arduino ARM and ChipKit Uno and Max32.
Partial release notes:
2.0   21 Jan 2013  -   added support for Arduino Due and Arduino Leonardo
            added support for the "AquaLEDSource All in One Super Screw Shield" on chipKit Max32
            added support for more display modules
            fixed a bug in printNumF()
            optimized drawLine()
            optimized 16bit data transfer
            optimized some 8bit data transfer
            added option to use pre-defined RGB565 values with setColor(), setBackColor() and fillScr()
            added functions getColor(), getBackColor(), getFont(), getFontXsize() and getFontYsize()
            added 16 VGA standard colors as pre-defined color literal
            rearranged the manual to keep related functions grouped together

Bob
   
1001  Using Arduino / Displays / Re: Is there a fast TFT Display for the Arduino Due? on: January 21, 2013, 10:12:03 pm
You Might get an answer... In the Due forum section. Here:    http://arduino.cc/forum/index.php/board,87.0.html

Bob
1002  Using Arduino / General Electronics / Re: Mystery magnetic sounder problem on: January 21, 2013, 01:17:19 pm
All of the 3  and 5V sounders I'v used in production have always had a seal tab covering the sound hole so that it doesn't become a solvent hole. 2 things come to mind, 1. The sounder internals may be soluble in IPA (the glue used in assembly and thus damaged ).  And 2. The IPA has a great deal of water in it and the water hasn't dried yet. Don't remove the 'stickers' until all fab is completed on the PCB that uses the sounder.

Bob
1003  Using Arduino / Project Guidance / Re: Solenoid matrix control circuit on: January 20, 2013, 09:34:28 pm
Very likely the 'Throw' is going to complicate things, I read 'somewhere' that a solenoid shuttle (the moving piece) has to be 50 percent longer than it's 'throw' or one half of the shuttle must be in the "Magnetic" circuit to work. I think that 'Latching Solenoids' are going to be a must, that or gravity and to get the displacement to raise or drop the 'pixel' you specify, Have you considered a simple lever @ 1/4 amp/solenoid is 50A total and although you may never (hopefuly) have that condition occur the capacity must be there. (it is an effective and important part of back EMF control.) The lever concept and semaphores (as hinged flags) might simplify what appears to be a mechanically challenging task. IMO the control is trivial.

Bob
1004  Using Arduino / General Electronics / Re: use ds1813-10 as temperature sensor ? on: January 20, 2013, 06:25:41 pm
That is the link I use for ALL my first searches try adding /key/Part# (whichever part you're looking for) to the end of the URL posted. That's a great source for ALL data sheets.
Now... Does anyone have a link to the National Semiconductor Linear Application Books (Vol 1 - 3)?
Those were my 'bibles' when learning things... Linear.

Bob
1005  Using Arduino / General Electronics / Re: Problems with Transistor TIP122 on: January 20, 2013, 06:16:08 pm
Try to remember that measuring transistor current gain in that manner is not recommended.
If you had a current source of sufficient capacity... With NO CURRENT LIMITING.
All you would have succeeded in doing would have been to destroy the transistor...
To see the effects of current gain you must use a transducer of some sort, a resistor is a good beginning and a higher voltage power supply would be required as well.

Bob
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