Ambitious LED Christmas Tree Project - Page 1
Forum section: electronics / beginners

author: Longhair
author_rank: Regular Contributor
timestamp: December 31, 2010, 11:55:30 am
content: I put together aLED Christmas treeand right after I finished it, I thought about improving it.The first thing that came to mind was Red/Green LEDs instead of only Red - which is currently on there. Of course there should be a non-flashing Yellow one on the very top to represent the star/angel/etc... After a while I thought that it should have more lights placed in a spiral to give it the realism of how a real tree is normally decorated. That would involve having to move the resistors, capacitors, transistors to the back of the tree and the only way to do that is SMD for everything... Instead of an ON/OFF switch, how about a low profile button on the back? Since there is a button, I could have it pressed to cycle through different lighting arrangements. That would require a chip that needs to be programmed to do what I would like it to do... Finally, since this would be a gift to family and friends, I want to keep the power simple - 9v battery that would double as a stand.Now comes the hard part - where do I begin in learning how to do all of this?I know I have a lot more to learn with just the basics since I do not fully understand how all the parts work together from the LED Christmas tree - posted above - as in how they knew which parts to use and what values and the formulas to find those values. Once I get that down, the next logical step would be programming - even programming at the same time while learning the basics wouldn't be a bad idea because that would give me a break from one another (alternate days or something like that). But what programming should I learn? The only thing that I know is that I should be able to be able to program and have things running on the computer before applying those things to electronics to keep from getting discouraged and giving it all up. Designing circuit boards is also something that I will need to learn. What software would have an easy learning curve and be affordable to someone running Windows?Any advice would be helpful. Thanks in advance

author: FreeThinker
author_rank: Frequent Contributor
timestamp: December 31, 2010, 12:22:23 pm
content: Google!Look for multivibrator, free running oscillator or try herehttp://www.hobbyprojects.com/multivibrators.html.hope it helps

author: FreeThinker
author_rank: Frequent Contributor
timestamp: December 31, 2010, 12:33:46 pm
content: For your second part of the question probably the cheapest and easiest option wound be to get a pic 2 dev kit for microchip.This will allow you to flash an LED on board and allow you to develop your software.Then just program your chip and build your board.You have plenty of time til next Christmas

author: Longhair
author_rank: Regular Contributor
timestamp: December 31, 2010, 01:36:37 pm
content: I refer to google pretty much every time that I need to have a question answered if I cannot find the answer using my own resources (books, bookmarks, etc.). The biggest problem I have when it comes to using google is finding using the correct terminology - something that I am still lacking. With so much information out there and no real formal training, it is hard to know if I am on the right track or not.I googled "pic 2 dev kit for microchip" and thePICDEM Lab Development Kitseems to be the most complete package ideal for my needs.Thank you for both the link to HobbyProjects.com and what I should be looking for in a PICkit2.

author: Psi
author_rank: Super Contributor
timestamp: December 31, 2010, 02:25:07 pm
content: individualy addressable RGB ledsonly way to go

author: FreeThinker
author_rank: Frequent Contributor
timestamp: December 31, 2010, 02:26:56 pm
content: Pleased to Help. I agree Google is great when you know what to search for but is a nightmare when you don't know the keyword.Used to use a search site called Dogpile years ago, very well named would turn up some very unexpected sh*t sometimes.It's still going I believe.Good Luck with your project and let us know how you get on.UPDATEYou may find this usefulhttp://www.tpub.com/neets/book9/36.htm

author: Simon
author_rank: Unknown
timestamp: December 31, 2010, 02:44:40 pm
content: you are looking at two different brances of electronics. The project you bought and put together is simply two multivibrators running alternately 2 sets of leds each, it is fairly simply but not 100% predictable but that was the idea, some built in randomness.What you are looking for is to move into microcontrollers, the most popular and I believe popular (put the bazuca's away atmel people I can read you minds) is the PIC range from microchip. As others said get the pickit2 development kit or if your more up for some do it yourself just get the pickit2/3 and a breadboard with some pics (12F615 and 16F88 are good 8 and 18 pin parts) and some discrete parts. As for software you can use assembler although it's generally a waste of time unless your into time critical projects, the most popular are Basic and C, take a look atwww.mikroe.comthey have compilers for both for pics and most other micro-controllers that are free.

author: Zero999
author_rank: Super Contributor
timestamp: December 31, 2010, 03:13:50 pm
content: The project you've built isn't configured for optimal. performance. The main problem is it will stop working when the battery voltage falls below about 8V because so man LEDs are connected in series. For maximum battery life from a 9Vbattery the device should be able to work down to 6V.What to you want to do? Add more LEDs? That's possible, the best way of doing that would be to add buffer transistors. Rather than a 9V battery, you could use six AA cells which will last eight times longer.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: December 31, 2010, 03:17:53 pm
content: Before spending any money try a Simulator.I've used the Oshon Pic Simulator and it is very good (But simulation CAN be slow)http://www.oshonsoft.com/has a variety of sims I would reccomend the pic ide as it supports the cheaper pic 16 devices which have a lot of support on the net.You can try it for 30 days but it is very cheap to buy 39euros for a single user licence

author: Longhair
author_rank: Regular Contributor
timestamp: December 31, 2010, 05:10:43 pm
content: Quote from: Psi on December 31, 2010, 02:25:07 pmNow that is interesting!!

author: Longhair
author_rank: Regular Contributor
timestamp: December 31, 2010, 05:18:25 pm
content: Quote from: Simon on December 31, 2010, 02:44:40 pmFor the already assembled Christmas tree, I want to be able to follow the circuit and say "this is the reason for ____ and it is connected to ____ because of ..." In other words, I want to be able to do more than just solder parts together. I want to understand the why behind it. Moving into micro-controllers feels like a natural progression, to me at least, when it comes to making something do that off the shelf parts (requires no programming) are unable to do. It opens up more possibilities than saying "I don't know how to do that, I guess I better find a different solution."My whole outlook in life is that I would rather fail trying because I will learn something from the experience than fail by not trying and not learning anything.

author: Longhair
author_rank: Regular Contributor
timestamp: December 31, 2010, 05:25:09 pm
content: Quote from: Hero999 on December 31, 2010, 03:13:50 pmThe whole drive behind the project is to learn something new and have something to show for the hard work.Adding more LEDs is a purely cosmetic thing to improve the looks of it. The reason I want to stick with the 9v battery is because right now I have some double sided tape on the bottom of the battery and the back of the circuit board. When you look at the "tree" straight on, it looks like it is standingOnce I get all the details worked out, a prototype working correctly, I want to put together a small handful of them and hand them out as little gifts - another reason why I am sticking to a standard 9v battery over coin batteries for instance.Thank you for the information about having the device work down to 6v. I just put that in my notes.

author: Simon
author_rank: Unknown
timestamp: December 31, 2010, 06:22:15 pm
content: as mentioned above look up astable multivibrator, that is all the circuit is two of astable multivibrators, you will find that the basic schematic is the same as what you have but with the leds removed and equal collector transistors.Micro controllers are a completely different thing. you may want to learn something of basic electronics before tackling them, writing code is all well and good but you still have to interface the microcontroller to the outside world and provide support circuitry.

author: Longhair
author_rank: Regular Contributor
timestamp: December 31, 2010, 06:44:34 pm
content: I know that I have a lot to learn before being able to accomplish my goal of the improved LED Christmas tree.Right now there is a goal in place with lots of smaller goals along the way. I have learned just by reading the replies already and I want to thank everybody for taking the time for helping out.

author: Zero999
author_rank: Super Contributor
timestamp: December 31, 2010, 07:33:18 pm
content: Quote from: Longhair on December 31, 2010, 05:18:25 pmI agree, you don't learn much from blinding soldiering components together, children working in sweetshops do that all day and know less about electronics than you.Have a look on Wikipedia for a good article on astable multivibrators.http://en.wikipedia.org/wiki/Astable_multivibratorQuoteMoving on to microcontrollers is a good idea but it's a good idea to make sure you understand the fundamentals first.Whilst microcontrollers are the most flexible parts there are lots of very simple problems which are actually better solved with discrete components.I would suggest learning a bit about op-amps, comparators and logic gates as well as microcontrollers.Quote from: Longhair on December 31, 2010, 05:25:09 pmI noticed the circuit contains a couple of drawing errors: the bottom cell is upside down, dots aren't always used to connect wires and standard convention is to have the battery on the left with the switch on the positive.Here's how to add more transistors to increase the power output so you can drive more LEDs. The extra PNP transistors enable it to switch more LEDs connected in parallel. Note also how I've only put three in series rather than four so it will work at a lower voltage.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: January 01, 2011, 05:55:37 pm
content: The Complete NEETS (Navy electricity and electronics training series) is available herehttp://www.phy.davidson.edu/instrumentation/NEETS.htmin PDF which you can download for FREE.Answers to asignments are NOT included if you are not 100% certain your answer is correct reread the lesson ALL answers are in the text.If you get stuck post on the forum.The module you need (for multivibrators ) is #9, but all are worth a read.

author: Simon
author_rank: Unknown
timestamp: January 01, 2011, 06:04:47 pm
content: thanks for that, just downloaded the lot