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# Need help with a project =)

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#### leopoldo

##### New Member
Hey guys, I need help with a lighting circuit project i'm doing.

Basically the circuit has 4 LEDs of different colour, with no manual inputs other than a 3V battery(electric cells) power source.

the aim is to get the 4 LEDs lighting up 1 after another in a continous pattern. And the LEDs are not supposed to just go off and on but rather from off state it slowly gets brighter and brighter till the max, then slowly become dimmer. once its completely off again, the next LED does the same thing.

but I'm having problem with every part of the circuit, like getting the clock signal and making the LEDs go brighter and dimmer.

Does anybody have any idea on anything apart of this circuit? Anything will help! Thanks!

#### Shax

##### Member
Hey guys, I need help with a lighting circuit project i'm doing.

Basically the circuit has 4 LEDs of different colour, with no manual inputs other than a 3V battery(electric cells) power source.

the aim is to get the 4 LEDs lighting up 1 after another in a continous pattern. And the LEDs are not supposed to just go off and on but rather from off state it slowly gets brighter and brighter till the max, then slowly become dimmer. once its completely off again, the next LED does the same thing.

but I'm having problem with every part of the circuit, like getting the clock signal and making the LEDs go brighter and dimmer.

Does anybody have any idea on anything apart of this circuit? Anything will help! Thanks!

Here's a hint....

Use a microcontroller and PWM....

#### leopoldo

##### New Member
i forgot something! the size requirement is a real problem! the height of the entire hardware shud be roughly 5cm X 5cm X 1cm

its because this is used as a base lighting for a crystal statue in a car.. so i cant have a circuit with wires running around. but i know it can be somehow cuz i saw a shop selling the same exact circuit as what i need

#### blueroomelectronics

##### Well-Known Member
If you saw exactly what you need in a shop why not just buy it?

#### agis68

##### New Member
Always is good to make and use your own circuit!!!

#### kpatz

##### New Member
The one in the shop was made (cheaply in China most likely) with a custom PCB and surface-mount components. Making the same thing yourself with veroboard and through-hole parts is going to result in a bigger hunk o'stuff to cram into your statue.

But, that Chinese circuit is using a microcontroller, so you can too. A 6-pin PIC can do it with charlieplexing of the LEDs. 5x5cm square should be easy enough, keeping the total height under 1cm might be a bit harder... does that include the batteries?

P.S. What color LEDs are you going to use? If you want to use blue, you're going to need more than 3 volts.

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#### michael moon

##### New Member
if you don't want to use a microprocessor , then you can get the fade in effect if you use two signals as slightly out of phase with each other so both 50 hz or what ever frequency but slightly out of phase, then as the phase shifts the difference between them graduly increases , as for the four led's turning on in sequence perhaps you could get away with using a 555 timmer and changing the mark to space ration to increase teh brightness and a serial latch register or 4 of them to turn on your leds in sequence the real question is what has it got to do ? 5cm by 5cm should not be a problem you could fit 20 plus leds on that size . i think your best bet is something in the line of a 55 timer with a mark to space ration alteration as your supply for the led's then some switching logic to turn them on , perhaps something like a series of flip flops using the sr latch to push the next led on while the previous turns off

#### mneary

##### New Member
Search almost any supplier for "rainbow LEDs" like this one at Electronic Goldmine stock #13897. US$1.99, runs on 3.5V 40mA which you can get from 3-AAAs and maybe 47 ohms which should fit in your space. If you're in L.A. then All Electronics has what apparently is the same part CAT no. LED-95 for US$2.00.

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#### Hero999

##### Banned
The supply voltage is 3V so a Joule thief style circuit is required for a rainbow LED.

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