novice led help

[Tresguey]

im a novice. i want to build a led chaser project. i am trying to do a little research on them. so i broke out my old bread board and bought some led's resistors a couple 555's and a 556 along with an assortment of transisters. my first goal was to just light up one led. i used the led series resistor sight to calculate the resitor needed. it said 430 ohm's. so i pluged it in to the bread board and it burned out two led's. i was useing a 9 volt battery to power it. my question is, was that the correct resistor? and if it wasnt how can i figure out the value of the resitor needed? its kind of disappointing if i cant get one to light up how am i going to get a chaser going on. any help will be great.

 

[jrz126]

What's the forward voltage and continous current of the LEDs?
Did you have the resistor connected in series? because it doesnt seem like 430 ohms should have burned them out.
Here's a good resistor calculator:
**broken link removed**

Dont get discouraged though, just takes alittle time. but be careful though, those LEDs are addictive. I started out playing with them a few years ago, and now I have 62 of them in the headliner of my car. (see links in sig for movies)

 

[williB]

i agree jrz , 20 milliAmps should have been the correct amount..
9V/430ohms=0.0209 A

 

[audioguru]

You will find that the little 9V battery won't light 2V LEDs very long in a chaser (7V is wasted), so I designed my 3V chaser project with 2 AA battery cells which runs down to 2V over their life, 74HCxx ICs that work fine down to 2V, and a pulse width reducing circuit that flashes each LED very briefly to save battery power and extend its life.
While I was at it I added a chasing speed control and LEDs brightness control that uses pulse-width-modulation. My circuit is so efficient that it doesn't have an on-off switch, just turn down the brightness control and let it continue to run.
https://www.electronics-lab.com/projects/games/003/index.html

After a while I modified my chaser project to use 3.5V ultra-bright white or blue LEDs and therefore used a 6V battery of 4 AA cells. They work fine when the battery runs down to 4V.
I got bored with my chasers just going around and around, so I modified both circuits to chase around a few times then pause, then chase again.
I have made these chasers with red, orange, yellow, white, blue and green LEDs.
https://www.electronics-lab.com/projects/games/004/index.html

Yes, I mounted my chasing LEDs on CDs (CD Roms from an ISP).

 

[Tresguey]

the voltage of the led's are 2.5 and the continous current is 20 ma. yeah thats the calculator i used. i am thinking that i may have set something up wrong. thanks for the help. i am not the kind of person that gets discouaged easy. i figure it is goig to take some time to figure this stuff out. and i did check out your link on your headliner. pretty cool stuff. thats what i kind of wont to do. in a room i want to make chaser lights to go around and in the ceiling i want to set up a star type of color organ. im sure i can do it but it is just going to take time. do you know of any beginer sites that may help also?

 

[williB]

to hook it up you should go from positive terminal through the resistor to the diode then to the negetive terminal..
also called a series connection

 

[Tresguey]

yeah that was the problem. i kinda forgot how the breadboard worked. so now that i got it lit im on a mission to try to get two to blink. one step at a time. lol. :lol:

 

[williB]

enjoy.. :wink:

 

[nos_slived]

I made a chaser using a 4046 driving a 4017. It ran on 9 volts, and the battery was good till about 4.5 volts, and could be less if you changed the diode. I dont have a schematic, but if you find the datasheets(or understand already) how these 2 ICs work, it is simple. 4046 sends out I/O or hi/lo pulses, which are interpretted by 4017, which moves the light in sequence.

 

[audioguru]

Have you seen what's in a 9V battery? Six very small AAAA cells are in new 9V batteries.
My chasers use 74HC4017 ICs and ones using ordinary red LEDs use only two AA battery cells that are much cheaper than a 9V battery but have 5 times the capacity, for nearly the same size.
My chasers' 74HC14 oscillators start and run with a supply voltage lower than 1.24V which is the lower limit of my LM317 variable power supply. Regular 4xxx Cmos ICs stop working near 3V.

 

[nos_slived]

You just went against yourself. It doesn't matter what batteries you use, it depends on the IC. And just because your's uses 2 AA's(which are close to the price of a 9V D) doesn't make it better. I have seen 2 pack AA's selling for 4 times the price of a D, and they were the worst batteries that I ever used.

 

[audioguru]

I'm talking about high quality Energizer alkaline battery cells, not those Oriental imports that are dead before they get off the boat.
Sorry, I meant their battery cells are dead, but frequently their people are also dead.

 

[Halogrunt1234]

Oh so thats the difference between a "C" and a "D" cell!
much more milliamp hours!
hmm.

oh yeah, you might just want to try to hook up 1K resistors with the LED's
That always seems to work.

 

[audioguru]

Why use 1K resistors with LEDs?
Why not simply calculate a proper resistor value for the LED current that you want based on its supply voltage? It's easy when you use Ohm's Law.

Watch out when you buy expensive Ni-MH rechargeable battery cells. You want a high capacity battery so you buy big C or D cells. Your circuit doesn't run very long with them. You look them up on the battery manufacturer's website and find that there is only a little AA cell inside!

 

[Tresguey]

i was using a 9volt battery because it was the easiest way i could connect power to my breadboard from the stuff i had laying around the house. i myself am just trying things out to see what makes things tic. my biggest problem is that i dont fully understand what makes the transisters or 555's and 4017 work. but ultimately i want my project to be powered on 110 ac. thanks for all the input as i am a novice.