Control 12 LEDS from Arduino

I agree. That's very cool 🙂

Now, first of all, remember that when yer talking to me, yer talking to an idiot, so, forgive me if I say something stupid...

So, here's my (completely uninformed and stupid) idea. Couldn't you use 6 output pins on the arduino, with 2 led's per pin, with one going one way, and the other going the other? This way you could light up 2 led's with one pin depending on which way you send the electricity. The led only works one way, but the pins work both ways

Or is that idea completely stupid ?

Not stupid, but you will not be able to turn both off or on at the same time

hj

@spyder

Or is that idea completely stupid?

I won't be honest! ? Let's just say it wouldn't work!

If you connected two LEDs in parallel to an AC source, the LEDs would blink alternately at 50/60 Hz, depending on where you live.

The digital pins on the Arduino are purely for output therefore current only flows in one direction, namely out or no current flows at all or just measuring whether they are in high or low states. This is because all the digital pins are connected using high-value resistors to the positive rail because one thing that electronic experts do not like is so-called "floating pins". These are pins that are neither absolutely positive or negative, but float between the values of Vcc(5V) and Gnd(0V).

Pullup and Pulldown!

The pullup is where your first connection is through a 10K resistor to the positive rail. And pulldown through a 10K resistor to the ground rail.

This is really important if you start playing about with Integrated Circuits.

There are RST (reset) pins that should not be left floating. Some output pins are also pulled down allowing the flow of current in both directions albeit a very small amount of current to ground, such as in the 555 timer chip.

I hope that this has given you a small insight into this slightly more complicated subject.

Thank you for the idea, but I need them to each be controlled on their own. The idea was to make a simple pair of dice for my kids board game. Most of the games have 2 dice in them which would equal 12 LEDS. I might just make 2 cubes and use the options offered so far, each as a separate project.

@garnold

How about this for an idea!

Using two digital output pins to control two 74HC595's, just using 6 LEDs on the IC output pins 0 to 5.

In the loop(), you supply a random number to each 74HC595.

Breadboarding 1980s technology and controlling 10 LEDs with discrete components.  I clock them with the ubiquitous 555 timer.  This is a good reason to use an Arduino because this took a week to get working properly.  My goal when I put this together a few months ago was to get back into basic electronics.  Now I appreciate micro-controllers!

I am new to the forums and poking around to get familiar with the content and layout here when I found this topic. Out of curiosity, wouldn't this be easily achieved using addressable LED's? I have been playing around with neopixels, they are so much fun! I see they come in a lot of shapes and sizes.

I recently built an 8x8x8 RGB cube, and uses a bunch of those shift register chips. I admit I haven't taken the time yet to fully understand just what they do, but its on my list. I also need to spend some time understanding the code. Anyway, as I was doing the build I was thinking how much different this would be if it was built using addressable RGB's.... perhaps that could be another topic!

Posted by: @ve1dx

Breadboarding 1980s technology and controlling 10 LEDs with discrete components.  I clock them with the ubiquitous 555 timer.  This is a good reason to use an Arduino because this took a week to get working properly.  My goal when I put this together a few months ago was to get back into basic electronics.  Now I appreciate micro-controllers!

You did a really nice job on the breadboard layout.   I too prefer to use hook-up wire for nice short flat connections versus using DuPont type wires that end up looking like a bird's nest.   So nice job on that!

Agree that microcontrollers have us spoiled.   But sometimes using something like a 555 timer is actually more practical and even easier in some situations.   I have an FPGA board that has a 50Mhz clock on it.  The problem is that if you want to reduce it down to just a few hertz so you can see things happening you need to write a lot of VHLD code and use a lot of gates to do that.  Sometimes it's far easier to just use a 555 timer as an external clock.  The beauty of using a 555 timer is that you can then also adjust the frequency externally as well by just using a pot.

So, yeah, I always keep my 555 timer IC drawer full.  It's one of my favorite goto chips. ? 

Posted by: @robo-pi

Sometimes it's far easier to just use a 555 timer as an external clock.  The beauty of using a 555 timer is that you can then also adjust the frequency externally as well by just using a pot.

So, yeah, I always keep my 555 timer IC drawer full.  It's one of my favorite goto chips.  

Indeed, James. Amazon had (and probably still has) a deal where you can order forty 555 chips for $5-6. They come from China, and it says "most" of them work.  Thinking "most" = "a few," I ordered two lots.  I made up a test circuit with a ZIF socket to try them out.  It turns out "most" = "all!"  I have 80 now.  A couple had the pins slightly bent, and I fixed that with tiny needle-nosed pliers.  If anyone is looking for a cheap supply, I'd recommend that route.  It takes about 4-6 weeks to get them, but you can't get them any cheaper.

With what type of project(s) do you use them?  I seem to recall having a 555 "bible" of projects circa 1976 that I can't find any more.  No need, I suppose, as the Internet is full of everything one would need.  The fact they are still in production after ~50 years speaks volumes — kind of like the 741 — the two "must-have" little ICs for any electronics hobbyist.

Posted by: @ve1dx

With what type of project(s) do you use them?

Most commonly I use them as a simple oscillator/generator.  The second most common application I  use them for are simple timers.  You press a button to charge a capacitor and the 555 timer will activate when the capacitor drains down over a given time.

But I have also used them for PWM drivers in the past.  No so much for that anymore now that microcontrollers have PWM pins.

I've also used them as waveform generators because you can get them to generate just about any shape of waveform you need.  I've used them for switch denouncing.  Audio ton generators, etc.   They're pretty versatile little chips.

Posted by: @ve1dx

kind of like the 741 — the two "must-have" little ICs for any electronics hobbyist.

Yep another favorite of mine as well.

I'm currently toying with the idea of designing a "Field Programmable Op-amp Array".   I'll be using SMD components to keep the boards as small as possible.  I'll also be using quad op-amp chips.  They don't need to be 741 op-amps.   In fact, I haven't really done a search yet but I'll probably find whatever SMD chips I can find that have the most op-amps per chip.   My goal is to build an analog neural network.   It's going to be an extremely simple one at first of course.  But if I can get that to work the way I want it to work then I'll have the confidence to shoot for a larger one.