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multifunction/colour LED array on batteries, possible?

fishmanstyles

Mar 22, 2012
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Hiya,

I would like to make an array of LEDs that run on batteries, what components would i need to accomplish the following functions:

multicolour LEDs as bright as possible, minimum 4 colours
run on batteries
selectable functions including single colour, colour cycle, solid colour and strobe
all to fit in a tube of maximum diameter of 25mm

are there bespoke components on the market that would go together to achieve all this?

many thankyou's

Mike :)
 

GreenGiant

Feb 9, 2012
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not including the fitting in a tube with a max diameter of 25mm I was going to say a small microcontroller....

for the criteria you have specified youre probably better off getting something that is already made.

You will need a micrcontroller chip, and a board to put it on (approximate cost: somewhere in the $50 range)

But then you can get something like this and do the same thing for less than 25 bucks

it would be a fun project, but very difficult to achieve with a reasonable budget
 

BobK

Jan 5, 2010
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If you can build your own PCB, then making a microcontroller circuit to fit in a 25mm tuibe would not be a problem.

You don't say how many LEDs your are talking about, that might be a factor.

Bob
 

fishmanstyles

Mar 22, 2012
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wow, that does look fun, but i was thinking a much smaller scale, should have specified better.

arrays of about 5 to 10 LEDs each (but lots of - so buying in bulk, costs should come down ok)

and the micro-controllers - i'm guessing like you get on those cheap horrible plastic toys at fairs etc that you basically keep clicking the power button to cycle through the functions
 
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BobK

Jan 5, 2010
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A microcontroller is a single chip programmable computer. The control box on the link GreenGiant pointed to most likely has a microcontroller in it.

Bob
 

fishmanstyles

Mar 22, 2012
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but can you get these micro controllers as components for the application i'm attempting?

I have found some info on printed circuit boards for the application i'm looking at, is that like a basic non-programmable controller? but I cant find any info on what these printed circuit boards are

"You can flash the LED on/off/on etc at normal current 20mA but you will find that if 50% of the time it is on and 50% off the LED will appear only half as bright as you increase the frequency.

For a higher frequency flash (eg 1000Hz or 1000 cycles per second) you are better to have a circuit with the LED having 5 times the forward current for 1/5 of the time.

So for 1 milli-second the LED will be on at 5 times the normal current (eg 100mA) and hence extra brighter than normal. Then for the next 4 milli-seconds the LED is switched off and able to cool back down before switching back on and repeating this process again. this will mean you will not loose any brightness from flashing."
 
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GreenGiant

Feb 9, 2012
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but can you get these micro controllers as components for the application i'm attempting?

I have found some info on printed circuit boards for the application i'm looking at, is that like a basic non-programmable controller? but I cant find any info on what these printed circuit boards are

"You can flash the LED on/off/on etc at normal current 20mA but you will find that if 50% of the time it is on and 50% off the LED will appear only half as bright as you increase the frequency.

For a higher frequency flash (eg 1000Hz or 1000 cycles per second) you are better to have a circuit with the LED having 5 times the forward current for 1/5 of the time.

So for 1 milli-second the LED will be on at 5 times the normal current (eg 100mA) and hence extra brighter than normal. Then for the next 4 milli-seconds the LED is switched off and able to cool back down before switching back on and repeating this process again. this will mean you will not loose any brightness from flashing."


Printed Circuit Boards (PCBs) are those green/blue/tan boards that all of the components are connected to, for each application you need specific connections, and hole spacings and a whole lot of things

What you are.... amost... describing is whats called Pulse Width Modulation (PWM) which basically says that the longer the pulse is high, the brighter the LED will be, thats typically how the brightness of LED's is controlled, but you always use the same current, not higher current.

Using a higher current can in theory increase the brightness but you risk burning the LED




I think i may have found something suitable,

but it has no information about power of what LEDs it can drive or how many..... any guestimation insights to this 'chip'?


http://www.liquidemotions.com/ProductDetails.asp?ProductCode=dropz-4-ic-chip-onl4

There is absolutely no information about the "chip" if that was me I would do a little more research on it, and see if you can obtain a datasheet for it
Or possibly just get one or two and fool around with them until you are comfortable with it and figure it out.
 

fishmanstyles

Mar 22, 2012
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Ah thanks, sounds good, there are LEDs on the same site too, one colour, colour changing, strobe, among others.... do these do their various thing on their own, or for example the colour changing LED is for use with a controller chip?

i'll order a few and see what they are i guess

and if i was to setup a real basic PWM circuit, what components go into this?
 

GreenGiant

Feb 9, 2012
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color changing LED's usually either need different voltages, or frequencies (PWM is very difficult with these) strobe means that when they have power they will pulse not stay on all the time
There are LEDs with a 3rd pin that controls the strobing

Ive used a 555 timer before for PWM, you can control duty cycle (how long its high vs low) and frequency very easily
Example here
 

fishmanstyles

Mar 22, 2012
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and the 555 circuit would be used with a normal (non-strobe) LED to produce strobe and control the frequency?
 

GreenGiant

Feb 9, 2012
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You would need a couple of them to achieve a strobe effect with brightness control

or if you want them to strobe at full brightness then you can use one but use switches to change the frequency to something really long (like 10 Hz which will make them pulse 10 times a second)

The only problem you will run into here is that you will need a lot of switches/relays and a lot of logic circuitry to choose between more than 2 functions (color, strobe, brightness, etc)
 

fishmanstyles

Mar 22, 2012
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It's the 40 - 100 Hz range that i'd want to be playing around with, but obviously thae brighter the better

i think this would be the over-clocking current, but at say a 10% wave form reference came in, to combat the brightness issue with higher frequecies, but reduce the waveform to prevent frying the bulb?
 

GreenGiant

Feb 9, 2012
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40-100Hz is not going to look like its strobing, its going to look like it is solid on, though depending on duty cycle it will look dimmer

you would want to use a current limiting resistor for a set amount of current the whole time, and then most LED's are rated to operate at 5 volts so you would keep that constant as well

The only thing you would change is the waveform,
lets say for 50Hz @ 50% duty cycle the waveform would look like a perfect square wave, high for 1millisecond, low for 1ms as the full period is 2ms (1s/50Hz = 2ms)

I guess I dont really get what you are asking....
 

fishmanstyles

Mar 22, 2012
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They are going to be moving in darkness, so you'd see the strobe effect from the higher frequency because of the momement

I guess I'm asking how best to get the LEDs the brightest possible during strobe (and how to set up the whole thing in the first place)

the one answer i came across regarding getting them brighter was to up the current - their solution to not burning the LED was to decrease the duty cycle
 

GreenGiant

Feb 9, 2012
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Alright so you will see some strobing if they are moving a lot and quickly

as far as increasing current, yes that will increase the brightness, to control the duty cycle you are going to have to have 2 separate 555 timers, one for the frequency of the strobing, and one for the duty cycle

to be honest though you will achieve about the same brightness as you would with the max recommended current, because decreasing the duty cycle is going to dim it a bit, I would say jsut try to find some really bright LED's they may cost a tiny bit more, but youll be saving yourself a ton of effort and timing issues
 
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