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106  Using Arduino / General Electronics / Re: 4 diode rectifier bridge on: August 20, 2014, 02:36:43 pm
It is correct.

You're supposed to assume the current that enters the bridge also is leaving the brigde.
There will be 2 diodes active at any given time the AC is present.
Current rating is per diode.
107  Using Arduino / Displays / Re: Backlight and I2C on LCD Display on: August 20, 2014, 02:25:37 pm
i missed your answer to my first reply.
The Fritzing doodle shows PCF pin 7 to be in use for brightness control.
As stated before, you need the resistor in the base of the transistor, don't forget that.

If you do want to use that PCF for such functions, it should be able to do something alike, but the PWM would need to be a software solution for this, and be probably at a relatively quite low frequency.
Not a thing to use when starting with this matter i'd say.

You need to know exactly what pin the library you are using expects for brightness and contrast control.
Sometimes you can set this, also something that should be explained in the libraries documentation.
108  Using Arduino / Displays / Re: Backlight and I2C on LCD Display on: August 20, 2014, 02:13:22 pm
My datasheet seems to be incomplete.
Which pin is the PWM compatible PCF8574 pin ?
109  Using Arduino / Displays / Re: Backlight and I2C on LCD Display on: August 20, 2014, 02:04:02 pm
You are connecting power lines direct to the back light, following that "do it this way and it will magically work" site.
(They are actually trying to invoke magic by mentioning it on this particular page).
Well, no magic there.
You are powering the back light LEDs, so it will light to the intensity set by the resistor you are using for this goal.
There is nothing controlling the LEDs from the PCF8574.
And there is nothing controlling the contrast either.
So your findings are correct.

Most likely controlling the contrast and back light will only work with noticeable difference between the values 0 or any other value.
That means any other value will turn it on (100 %), while value 0 will turn it off.

By the way, did you know a potentiometer consists of 2 resistors in the way it is applied here to control the contrast ?
It doesn't do what you seem to think it does the way you hacked it.

I take it that the display works but you are looking for away to control back light and contrast ?
110  International / Nederlands / Re: Program Arduino Pro Mini with an Arduino mega 2560? on: August 19, 2014, 03:10:12 pm
Hoi, beide personen welkom op het board.

Wees duidelijk wanneer je een vraag stelt.
Zoals poeg al zei, laat weten wat je al gedaan hebt, wat je verwacht(te) en wat je kreeg.
Anders moeten de mensen die je willen helpen gaan gokken en dingen aannemen, en dat niet echt handig als je hulp wil.

Verder moet je ook proberen misverstanden te voorkomen door duidelijk te zijn.
Een mini is iets anders als een pro mini, en daarom moet je die termen niet door elkaar gebruiken.

poeg lijkt aan te nemen dat je je pro mini wil programmeren via de ICSP methode, en das helemaal niet vreemd.
Maar is dat wel wat je wil ?
Wil je niet de mega 2560 als USB - serieel adapter gebruiken ?

Het nadeel van het programmeren via de ICSP methode,is dat je daarmee de bootloader kwijt raakt, tenzij je die juist wil maken.
Daarmee verlies je dan dus de mogelijkheid om het ding via de seriƫle poort te programmeren.

We weten dus niet wat je wil, dus zitten we nu te gokken en dingen aan te nemen.
Dus: begin eens opnieuw en vertel wat je precies wil doen, en mogelijk waarom je dat wil.
Dan is de kans veel groter dat iemand je een antwoord op maat kan geven.
111  Using Arduino / Displays / Re: Odd Display Issues with 1602 HD44780 on: August 18, 2014, 03:27:26 pm
What did you figure out ?
Help others that run in the same trouble by telling what was your problem and the solution.
112  Using Arduino / General Electronics / Re: Where should I connect fuse? on: August 18, 2014, 11:10:50 am
What will happen when GND gets disconnected from the board (by a blown fuse) , but 12 volts and 5 volts are still connected to that circuit ?
113  Community / Website and Forum / Re: User profile page blank on: August 18, 2014, 11:01:51 am
You could have it point to [snip] [/snip]  which is the link i used to show that picture.
I guess that will be as good as a reset.
114  Community / Website and Forum / Re: User profile page blank on: August 17, 2014, 05:53:45 pm
I'm using Firefox under win 7 and XP, including adblock plus and ghostery.
Haven't seen these problems.
I have no avatar set, so i'm seeing some shadow profile picture in grey.

That pic is above this line, but i guess you guys can't see that one either.

Just to let you all know this doesn't occur on all Firefox with ABP installations.
115  Using Arduino / General Electronics / Re: LED behavior changes when moving hand near or touching on: August 17, 2014, 05:05:39 pm

You shouldn't ever use a bare 595.
Be sure to have some capacitors handy (100 nF is widely used for this).
Put them across all power lines of each chip you're using.
Read datasheets of chips before using them.
Your body interferes with the interference, so you'll see some interaction/
116  Using Arduino / Motors, Mechanics, and Power / Re: Controlling vents with temperature and rain sensor on: August 17, 2014, 04:39:34 pm
Ok, that's step 1
I would make the next step to process that data coming in.
I guess displaying that data doesn't do it for you, and am imagining you want to do something with it.
So, see if you can have the LED on pin 13 of your Uno turn on when some temperature you are aiming for is met.

Following steps would be to have an upper and a lower threshold (and so create a hysteresis you will without doubt need ).
You can use a single LED to display multiple statuses, for instance by having it blink.

But first of all you need to make a simple plan, indicating your goals for this project.
Try to set it up so that you can work on different goals in case one of them gets stuck (like perhaps while waiting for parts).
Work out each of them (as Terry King already pointed out), after which you can combine them into you final goal.

The parts:
Those relay boards might be able to control a single motor.
Do you have a single one for the 5 motors, or do you have or plan to use a relay per motor ?
Switching on 5 motors at the same time isn't a very good idea, not even if that relay tells you it can handle 30 Amperes.
That same source also has a similar board that has 4 of these relays on board.

Personally, i found a display with 2 lines of 16 characters very helpful for debugging.
If you plan to have a display in your setup too (there are lots of possibilities here), you might want to get that working with some priority.
117  Using Arduino / Displays / Re: QC1602A (v2.0) Contrast not working? on: August 17, 2014, 05:29:01 am
There is no way to do that.
You might think you'd be able to press the LCD board to the header pins, but that would in no way be stable.
Bending the header pins might also seem to be a good idea, but these pins typically don't bend that well, and you'd have to have some header with pins that are longer than standard.

Soldering is the way to go.
And practice a bit before you do the soldering to you LCD board.
There have been some pictures on this board, showing really horrible soldering jobs, asking what might be wrong with that setup.
118  Community / Website and Forum / Re: Nick Gammon on: August 17, 2014, 05:02:51 am
Welcome back, Nick !
119  Using Arduino / General Electronics / Re: Arduino undo controlling prebuilt modules on: August 16, 2014, 01:17:30 pm
Hi and welcome.

Yes, it's possible.

There would 20 LEDs (doesn't matter what type would be used in the dark) and one of these:

Well, it does matter.
You're asking about what battery to use.
The type of LED you'll be using will have something to do with that.

The gadget you're showing has a controller like the one in an Arduino built in, just from an other brand.
Do you want to use that gadget or do you want to build something like it ?
120  Using Arduino / General Electronics / Re: Does a LM7809 help me boost arduino uno's 5V to 9V? on: August 16, 2014, 01:07:24 pm
Tell more about what you want.
And ask questions politely instead of telling people about your demands.
And stop cross posting.
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