Hello All, I need to design and build a light box for a cerebral palsy child. The building side of it I am quite happy with but the design side I'm not. It needs to consit of 9 sets of 3 leds, when the power is switched on ( Ihave a 4.5V dc output that I would like to use) I would like all 9 of one colur to fade in for a couple of secs then fade out, as ithey fade out I would lke the second set of the next colour to fade in for a couple of seconds and then fade out followed by the third set to fade in and out as the other have. It needs to repeat this until the power is switched off.

I don't have access to a PIC programmer so would like it to consist of off the shelf components if possible.

Thanks for your help in advance.

Regards

Darren

 

Hi Dazza and welcome to the forum.

Are you another ex-Electronics-Lab member?

What about adapting a fading red-eyes project?

http://blog.makezine.com/archive/200...d_project.html

You can build sereral of them so the different LEDs fade at different rates.

For a more ordered procedure a PIC is probably the cheapest way to go, you can buy a programmer or make one fairly cheaply and PICs aren't expensive.

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Hi Dazza

If you are in Australia then I can help with both hardware and software.

If your elsewhere then I will happily help with software and advise on hardware.

I think you will need a pic.

Mike.

 

So, there are three sets of LEDs. When power first comes on, the first set slowly increases intensity up to full brightness over, say, 4 seconds, then immediately begins to dim again at the same rate. The second set comes up while the first set is dimming so when the second set gets to full brightness, the first set is down to nothing. And then this repeats for the third set, but now when the third set dims, the first set comes back up again. Have I got that right?

This is a job for a uP alright. But if that is definitely out of the question, then the next best approach might be a
- a set of three monostables, each triggering the next and all with a 4 second output pulse. On power up, they are reset and the first one is triggered, then they daisy chain around in a circle. The output of each feeds a square to triangle converter (eg. a FET charging a capacitor at constant current). The output of these are buffered and drive the LEDs.
- or, a digital circuit with three sets of up/down counters. ON power up they are all reset. A clock runs, feeding the first counter. It counts up and when it reaches max count, it counts down. At end of count it enables the next counter to do the same. Each counter feeds a resistor ladder D/A which drives the LED buffer. Boy, this is going to be a bit complicated. I think you should use an AVR or PIC.

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RadioRon

 

DAZZA76,

Out of pure curiosity, since you said this for a "cerebral palsy child", does this have a clinical purpose?

Ken

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hello all, thanks for your replies.

I touched on Electronics about 11 years ago during my apprenticeship but not done too much with it since.

It is looking more like a job for a PIC. I must admit I don't have any experience with their programming or the hardware to do it so any suggestions would be grateful. Unfortunatly I am not in Australia but in the UK.

I have a friend who has a Cerebal Palsy child and they had a light box that had the wrong voltage adapter plugged into it, only the components are not accessable to replace the knackered ones so was going to start from scratch on the design.

Once again thanks for the replies so far.

Regards

Darren

 

Which components got blown? It's possible that more easily accessible replacements exist.


Torben

 

Hi, guys,
I'm in need of some "catch-up" re electronics terms. Do you mind if I ask what a uP, an AVR, and a PIC are?

Thanks

 

Sure, but first I'm gonna have to hit you with the obligatory "please start your own thread for your questions" comment.

OK, that's out of the way, so:

• uP: microprocessor. Spelled that way because on this board software a u looks like a µ. which means "micro", but µP looks kinda funny.
• AVR: A fairly advanced but still approachable uC (microcontroller) from Atmel. More information: http://en.wikipedia.org/wiki/Atmel_AVR
• PIC: Like an AVR, but slightly different, from Microchip. More information: http://en.wikipedia.org/wiki/PIC_microcontroller

PICs and AVRs can often be used for the same tasks (with different pinouts and coding, of course), and while there are plenty of AVR pros on this board, there are more PIC experts.

Also, check out Nigel's excellent PIC tutorials at http://www.winpicprog.co.uk/


Good luck!

Torben

 

Hello Torben, I can't tell which ones got blown as they are enclosed in an epoxy resin of some sort so can't get to them let alone see them.

Regards

Darren

 

It is MOOD Lamp using PIC16f628
As any way you are will to involve into PIC and their programming, Perhaps you can first build PIC programmer, like Junebug (a PICKIT2 compatible and with a built in tutor across 16F88 or 16F1320) being sold as a kit, from www.blueroomelectronics.com

It will help you from now on hope.

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Regards,
Sarma.

 

Well, dang. So much for that then. In that case, I'd agree that learning enough to do this with a uC would be the way to go--or if you can't do that for some reason or this has to be done fast, then perhaps you could get someone to adapt an existing PWM LED-control project to this.

If PWM is new to you, it means "Pulse Width Modulation", and just means that you'd be controlling the amount of current delivered by switching the LEDs on and off too fast to see, and varying the brightness by altering the "on" durations vs. the "off" durations.

However, I warn you: once you've learned to use a microcontroller, it might be hard to stop seeing uses for them everywhere.


Torben

 

DAZZA76,

Since you look like you're headed for a µC PWM solution I have a question. With 3 sets of LED's fading in and out...does one set fade all the way out before the next set starts to fade in? Or, do they overlap with two sets partially on some of the time?

Ken

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"To invent, you need a good imagination and a pile of junk."
Thomas A. Edison (1847 - 1931)

 

Was thinking of learning Pic have done some programing before what do you think would be best way to learn it.

went into this www.blueroomelectronics.com[/url] and the projects were in US $

 

Check out Nigel's tutorials at http://www.winpicprog.co.uk/ and do some reading/googling on PICs. Get a PIC--maybe a PIC16, and build or buy a programmer for it, and work your way through the tutorials.

As for the prices being in USD, that's pretty normal for a site expecting to do international business. At any rate, click on the "Where to buy" link on the left sidebar menu, and scroll down to the eBay Creatron Electronics link and click it. Once the page has loaded, go to the location bar in your browser and edit the URL so that instead of "http://stores.ebay.ca/Creatron-Electronics" it says "http://stores.ebay.co.uk/Creatron-Electronics", and hit Enter. You will be taken to the UK eBay page, with prices in pounds.

One last bit of advice: when using forums, it's not good form to hijack someone else's thread to ask your own questions. It's better to start your own thread for any questions you might have.


Good luck!

Torben