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Newbie needs help with two LED circuits

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New Member
Hi there,

I am currently working on a small project and am an electronics newbie... I can read a basic circuit diagram, but beyond that (making my own circuits) I am lost...

I am trying to acomplish the two following ideas

1) 10 or 12 LED row that fades in and out slowly on a continous loop (i.e doesn't stop until the power is removed)

2) 10 or 12 LED row that "scans" back and forth (think Knight Rider or Cyclon)

both of these would be run from +5v

Thank you so much for any help you can give


I'd recommend the 16f57 for this purpose.
this is a small microcontroller.

you just connect the LEDs 1:1 in that case,
no special circuit design.

but no one can know the equipment that is available to you.
or if you have access to materials like $1 prototype boards on the market.

such a flashlight that you describe could be made for about $5, powered by USB, including almost everything.

I reply because eventually i want to make a 16f57 LED matrix PCB, which also could be used to control a flashlight as well.
It seems to be a popular circuit.

when I was younger i've purchased some flashlight kits, based on the CD4017.
but that's not a microcontroller.
they suffered from static problems back then, I remember, because I had more than one of these kits.
might have been stuff manufactured in the early 1980s, and back then, horribly expensive.


Active Member
Do you understand ohms law and the basics of a diode, particularly an LED?
These can only be hooked up in parallel at 5V. What is your power supply? You will need to be able to handle up to 10-12 * 20mA = 200mA


New Member
I am a complete newbie when it comes to electronics. (Well i did electronics at school about 20 years ago :D) So I need to relearn about ohms law etc... Hence the reason I am here :)

AS for equipment at hand... I have an assortment of basic electronic components, but NO way to program things (GAL's Eproms etc)... I do have some project boards and a lot of perfboard...

+5v - LED - LED - LED - LED - LED -LED -LED -LED -LED -LED -LED -LED - Ground

I would like in project one for the lights to chase back and forth (they will be laid out in a line about 20 inches long)

in project two they will fade in and out slowly on a continuous loop...

now reading above it looks like as I am running +5 I will need to run these in parallel making stringing them out harder but not imposible (mmm lots of wires :) )



New Member
That's great... thank you very much :)

Once I have the array from that application how would I go about making them "chase" or "fade"


New Member
Do a Google search for "Knight Rider Circuit". There are numerous examples which are quite easy to understand and reproduce.:)
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