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61  Using Arduino / General Electronics / Re: Ethernetcable and Dupont Connectors on: January 27, 2014, 06:46:49 am
As a general rule (but exceptions always exist), you would have MALE pins on a PCB and Female pins on a cable.

I must misunderstand you since I don't quite follow your statement; "I thought the housings were uni, and the pins are male/female."     It is true that they will accept either pin style... but male is far less common. 

Males sticking out of the connector are just... well,   odd.  (unless you need them that way, of course)
62  Using Arduino / General Electronics / Re: help with shift register on: January 15, 2014, 06:38:29 am
It's also common to use the 595(output) in combination with the 166(input) sharing the same control bus (data/clock/latch) thus keeping the directional parts separate.
63  Using Arduino / General Electronics / Re: Relaying/switching 2000w at 240v on: January 10, 2014, 09:12:26 am
This is what you want to use.  And add a heatsink.
64  Using Arduino / General Electronics / Re: negative wire problem on: December 27, 2013, 10:18:07 am
Where are you getting such bad ideas about how transistors really work.

Your drawing is wrong,  For one, you are missing a base current limit resistor.  Are you sure you have a PNP transistor?  Because that is what you have drawn... and that would be the wrong part here.

65  Using Arduino / General Electronics / Re: Choosing BJT or MOSFET on: December 24, 2013, 07:49:37 pm
So let's put this out there.  Using a MOSFET does not make you more "cool"  but it can make your motor driver run cooler.

A good designer uses the right tool or part for the job at hand.
66  Development / Other Hardware Development / Re: Breadboard compatbile ATmega1284P board with V-USB on: December 20, 2013, 06:46:37 pm
And it's even pretty...

67  Using Arduino / General Electronics / Re: XBee RSSI out to Arduino Mega on: December 19, 2013, 07:45:26 am
Unless you are playing with different crystals, PWM won't frequency/period change.  I mean, you can manually change it... but that requires code.  The PWM hardware and the UART hardware are isolated and one does not affect the other.
68  Using Arduino / General Electronics / Re: Lithium cells / batteries. More efficient to step-up or step-down on: December 19, 2013, 07:05:56 am
For what it's worth, here is my opinion.

 A switching regulator in a step down configuration is usually 80-90% efficient in most cases.  You will not get that kind of efficiency from a step up or boost scenario.  In simplest terms, if you boost the voltage, you get lower instantaneous current.
69  Using Arduino / General Electronics / Re: my display lights some LED's very lightly and it should'nt do that on: December 15, 2013, 10:39:45 pm
A "schematic" is still our language... no matter how much time it takes.
70  Using Arduino / General Electronics / Re: Smaller alternative to breadboard? on: December 13, 2013, 08:19:17 am
Note: I think Coding badly pasted badly... :-P

These work too...

AKA  Dolphin Multiwire splice connectors... used in telephone industry.
71  Using Arduino / General Electronics / Re: Transistor as two diodes on: December 13, 2013, 07:43:32 am
More stuff you didn't need to know...  when the team at Bell Labs told their boss they had success in the lab, he was supposedly not pleased... he wanted them to show him a Field Effect Transistor and not the transistor we now know as  Bipolar Junction Transistor.  The BJT was proven to have the characteristics they wanted (signal amplification) so it was a success and announced to the world a month later.
72  Using Arduino / General Electronics / Re: Aquarium Controller Circuit Design Advice on: December 10, 2013, 09:40:48 am
Does any detail in the drawing warrant that it be uploaded as 5619x4044 pixels in size?  Please try to shrink images before posting.
73  Using Arduino / General Electronics / Re: Security for Arduino. on: December 04, 2013, 10:08:50 am
Assuming we are not talking anything more than plain vanilla arduino (not DUE or some other larger variant) then we are talking about something like an ATMEGA328.

A commercial design based on a generic Arduino (bootloader and all) is rather crude since it really is just an enhanced development platform.  From a coding perspective, you have made it easy for someone to replace your firmware.  Maybe that is not a concern... but to others it is a big security issue.  You are also subject to any coding errors made by 3rd party library developers.

Consider that the arduino is mostly a "proof of concept:" solution.  A commercial product really should get re-written from the ground up when creating the final embedded device using your own AVRGCC code.

Using the AVR Atmega328, programmed via ISP (maybe carefully crafted in AVRGCC and not using "sketchy" libraries) , without the bootloader, and with security fuse bits engaged means that you have a good standalone solution, that is reasonably secure and you are using the 328 as an embedded controller... as Atmel intended.
74  Using Arduino / General Electronics / Re: Help with transistor problem. TIP120 switching/control circuit for a motor/ on: November 30, 2013, 10:50:04 am
My belief is that they probably worked before you got the wiring right.
75  Using Arduino / General Electronics / Re: Help with transistor problem. TIP120 switching/control circuit for a motor/ on: November 29, 2013, 02:48:23 pm
The diode doe not go across the Emitter/Collector pins... it goes "across the motor pins" from the Battery Source, the cathode end,  and the Collector pin (middle pin)  which is the anode end.
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