[exceeds the maximum rating of the chip]

Witch in reality puts out 6.24vdc and makes my scanner blink crazy.

If your arduino runs off an r/c oscillator, its frequency is more dependent on the voltage, but not that dependent.

AVRs can work comfortably at 6.24v. If you are really concerned about it, you can put a diode or an led in serial + a resistor to pull down the voltage.


Moderator edit: dhenry was banned for making this post. The quoted figure of 6.24V exceeds the maximum rating of the chip. This is not the first time that dhenry has made completely false assertions. Strikeout added by me. (Nick Gammon)

This thread seems to suggest that is not true, but I could be completely wrong?

You are not wrong. People saying "no" in that thread are wrong.

Not only it can be used as input, in some cases, the same pin can be used as input and output at the same time.

And it is a pretty old idea for embedded programmers.

Does anybody know the code that would help me do this.

Programming is simple: all you need to do is to pretend to be a computer trying to replicate activities that a human would otherwise perform to achieve the goal. So in your case, ask yourself how YOU as a human would have done here to achieve your goal.

Once you have that cleared, it is a breeze to tell the computer to do it for you.

The power busses at the top left corner of the picture ( red, orange, yellow and white wires ) are not connected to where you bring in the power at the top right of the picture (blue and white wires).

due to optical illusion. You can count the pins, from right to left, as the leds for sure  work so pin 15/16 are right.

One has to separate the vagrancies of the workman from his tools before casting judgement from on high.

Right on. As they say, only incompetent carpenters blame their tools.

The 74HC595 can only output.

You can make it read too.

i found this just now online:

That's the basic structure.

is this true or just for legal purposes?

It is true.

I was hoping this can be done with Arduino

Yes - in principle. No - in practicality.

The programming is reasonably involved, especially if you want to code to a logic graphics interface, for portability reasons.

However, if you are willing to use a faster / cheaper chip, NXP offers emWin, completely free of charge and without any limitations, for its line of mcus. My experience with emWin (both on lpc and other chips) has been nothing but outstanding.

im not completely clued up with electrical components

In that case, don't work on mains.

Try something simpler / safer.

For me I guess a normal pot would be ok since I only need to.

Just so you know, there are digital pots that can be incremented / decremented via up/down buttons, making them far more usable here.

2W led down-lights

They are fairly (read: very) difficult to dim.

If I would you, I would start with regular incandescent light bulbs: you can dim those things easily with a bridge rectifier + mosfet, if you are OK with floating the whole dimmer.

good riddance.

No language (or any tool, for that matter) can do everything effectively and efficiently to everyone's satisfaction - that's why we have so many different langues / tools.

Judging a language's "inferiority" on its inability to perform a task is futile.

it too is ridiculously long.

That particular piece of code is actually well written. It's well structured and well commented. In particular, the use of all the defines helps make the code more portable and more readable / maintainable. That's how one is supposed to have written code pieces in C - I would have put it in a .c/.h file for that's for another discussion.

The actual code being executed are towards the bottom, if you wish to live with magic numbers - a very bad way of programming.

The device is i2c, so it can be easily coded as such. A 15 minute job,  max, if you want to roll your own.

Giving all three separate latch controls IS an attractive idea.

It doesn't solve your problem: you still need to send the data 3 times to update any bit.

A 16 MHZ MCU compatible crystal is about $0.50 and add a few more cents for the 2 capacitors needed.

Those are 5ppm crystals?