Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

I need to get/make a circiut board for my led project

Status
Not open for further replies.

miamimac

New Member
Your Question:
I need to know how to hook up a set of 4 sets of 7 - 3v 20ma leds so that each led in the set lights in sequence. They will be powered by 8-aa batteries providing 12 volts (more batteries can be added if needed)
---led1----------------led1----------------etc
--------led2----------------led2-----------etc
-------------led3----------------led3------etc
------------------led4----------------led4-etc
I would also like to add an additional 4 sets of 4 led's and 7 constant on led's, If I have to add a seperate power source for these it ok.
I know led come in different v,mA and lcm so if what i am asking cannot be done with 3v led please let me know an alternative, I need the led's to be as powerful as possible. diagrams in laymans terms please
 

audioguru

Well-Known Member
Most Helpful Member
If your LEDs are 3V each and your battery is 12V that drops to 8V as it is used, then two LEDs can be connected in series and in series with a 270 ohms resistor to make one string. Two strings use 6 LEDs and the 7th LED can have a series 430 ohms resistor. The total current for all 7 LEDs is 65mA when the battery is new.

A CD4017 is a sequencer IC that needs a clock made from a 555 IC oscillator. The CD4017 has low output current so each of the 4 groups of LEDs need a transistor to drive them. The transistors are driven from the outputs of the CD4017. The 5th output of the 555 is connected to its reset pin.
 

miamimac

New Member
I appriciate your reply, but since I am new to all this, it is very confusing. Is there anyway you can draw a diagram that I may be able to understand and dupliciate. This project is very important to me, but since this is all greek to me, I need the simple way. I don't understand if you are saying that it can or cannot be done. If voltage is the problem, I could add an extra 8pack of AA batteries so that the voltage would be enough to power what I am trying to do
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
One problem is you need to define "sequence"

Start out with
1: a b c d e f g
2: a b c d e f g

Is seq 1a 1b 1c 1d ... ... 2a 2b 2c ....
 

miamimac

New Member
OK. sequence is as follows:1a,1b,1c,1d... 2a,2b,2c,2d... for each string so that the (a) led in each string will light up, then the (b) led in each string and so on.. ie:
1a---1b---1c---1d---2a---2b---2c---2d---3a---3b---3c---3d---
4a---4b---4c---4d---5a---5b---5c---5d---
6a---6b---6c---6d---7a---7b---7c---7d---
all (a) lights wired in series, all (b)lights wired in series and so on so that at any one time there are 7 led's on in a chasing pattern (according to the programed sequence)
4 sets of 7 - 3v 20ma leds so that each led in the set lights in sequence. They will be powered by 8-aa batteries providing 12 volts (more batteries can be added if needed)
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Top