This should be simple! All I want is to be able to randomly switch on and off a small group (2-6) of white 3v leds that independently fade in and out - and drive it all from 3v or 6v lithium coin batteries.

I don't know whether to explore specialist programmable chips (e.g. Maxim 6946) or can this be done with a combination of timer (low voltage 555 variants) and op amp fader circuits? I've explored these separately but have no idea how to combine random on-off periods lasting 5 -20 secs WITH fading in and out of the different leds over 2-4 secs.

Or simpler, randomly switch on - off groups of flashing leds over 5-20 sec periods.

The aim is to randomly illuminate the leds so that the overall lighting effect is intriguing and not predictable. And I don't have space for complex, big component circuits. Give it up girl! It aint never gonna happen.

I know Ohm's Law and can solder but that's about it!

 

I'm working on an article for something similar. It might be finished in a couple of weeks.

There forum edition, where I do my work and rewrites.

LEDs, 555s, Flashers, and Light Chasers

Chapter 12, special LED effects.

You may be biting off more than you can chew for 1st time project. I have a set of tutorials for beginners, the AAC book above is also a good resource.

Bill's Index

The 555 Projects (good place to start)


Welcome to AAC!

 

I'll look forward very much to your article and browse the links you gave.

Do you think 'Circuit Wizard Simulation' software would help me? I have difficulty conceiving schematic layouts as printed circuits. And I've been laboriously designing pcbs in Adobe Illustrator. The New Wave software seems to brainstorm two sided pcb layouts well and shows the effect of component values on timing too?

My inner voice agrees I AM biting off more than I can chew. But at least I'll get an overview if I then hand it over to a professional.

 

Thats why our lips stretch.


So we can bite off more than we can chew... Just chew longer, or get someone else that already chewed it to regurgitate it back to you.

yum. Education tastes great!

 

I would highly recommend a protoboard. It is good practice, and you can buy breadboard designed around protoboard.

I also use regular breadboards, something like this I helped a gentleman design a while back...

You will this group in particular willing to teach at any level, if you're willing to learn. There is also links to a text book at the top of this page, the centerpiece of AAC.

A good first project would be something like this...

555 Hysteretic Oscillator

Don't let the name scare you, it is a very simple LED flasher. It needs more voltage than you are aiming for, but if you go through the 555 projects you will see several low power LED flashers.

Like I said, I'm in process of writing even more schematics.

 

Wow! Now I've got'n my feet wet! Will follow it all up Bill thank you, and thanks for the encouragement Retched! Hey I just brazed both halves of my silver locket together when it was supposed to be just the hinges!? But life is a journey and .. tomorrow's another day : )

 

Hello,

Here I have a disciption of a flame simulator.
http://www.schakelingenonline.nl/schakelingen/lichteffecten/9.htm

You can replace the lightbulb (lamp) with the leds and the correct resistors.

The text is in dutch, but the drawings will tell a lot.
Here are some words translated:
Spanningsverloop : change in voltage
Blokspanning : squarewave voltage
Driehoekspanning : triangle voltage
Driehoekgenerator : triangle voltage generator
Versterker : amplifier
Condensator : capacitor
Lamp : light bulb
Bovenste grens : upper limit
Onderste grens : lower limit

Greetings,
Bertus

PS If you have questions on the dutch text, just ask
don't be afraid to make some mistakes, it can happen to everybody (even me).
You will learn a lot by experimenting.

 

Here is the Google Translate link to the flame simulator page Bertus linked to.

This link will translate Dutch to English: (For the most part)

http://translate.google.com/transla.../schakelingen/lichteffecten/9.htm&sl=nl&tl=en

After that, the page is mostly understandable. The schematics are easy to follow. They give breadboard and PCB layouts.

 

Hello retched,

That looks good.
Nice to know google has the tool for it.

Bertus

 

Im sure you have a stash of sites I would love to see. Now you know that it is possibile for google to do the translating.

So keep 'em coming.

http://translate.google.com

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Thanks for all the ideas! I'm coming to the conclusion that proprietary solutions like Maxim's are the way the mainstream miniature illumination market (eg the car and telecoms industry) is progressing - until the Chinese put it all on a pin head around 2012! But soldering Maxim's MAX6946 16 lead chip only 3mm square is out of the question for a cottage industry like mine

So now I'm thinking PIC programming OR op amps. I'll be very interested to see Bill's new circuits when published. Meanwhile I'm mulling over learning more about programables via Circuit Wizard (www.new-wave-concepts.com/ed/circuit.html) and Genie (www.genieonline.com/)

PICAXE seems to be more full featured but scary

It's the random fading control that's the key I think to keeping viewers intrigued for longer than predictable flashing. Suspect Bill's next thoughts may prove to be an altogether more elegant solution without the mind-numbing pages of programming! Here's hoping.