Gameboy Color DIY frontlight

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Gameboy Color DIY frontlight

Postby thor17 » April 12th, 2013, 7:06 am

Hi,

recently I watched a few videos on youtube about frontlighting a Gameboy Color and thought, that it's sooo nooby to destroy another console just for modding another one :evil:
So I searched for a good mod, that doesn't need to destroy a Gameboy Advance SP. There was nothing available, anyway I didn't found something. Then I decided to make my own mod.
I bought acrylic sheet (1mm thick) and cut it to a size of 50x50mm. I've ordered diffused protection film to spread the light properly. Of course LEDs are needed, I've ordered 50 white 0402 SMD LEDs from China, they were very cheap.
As you can see when you take a look on my layout, I'll use 9 LEDs per line. There is no need to use so many LEDs, but I wanted to make a mod that overshadow every other, even the commercial backlight mods for the old DMG Gameboy :mrgreen:
I hope the light spread will be very good. I'll use two lines, 18 LEDs for one frontlight. Of course, the pcb that drives the LEDs can more, than just put out a certain voltage(about 32V) and a certain current (8mA). It's possible to control the brightness with a potentiometer that will be connected to the PIC MCU. That's not everything, the PIC also does measure the battery voltage. A bi-color LED (green/red) that is used instead of the red LED of the Gameboy, is controlled by two PWM outputs of the PIC, so it's possible to show the battery voltage by mixing green and red until the voltage is critical and the LED is flashing red :)
Tomorrow or in a few days, I'll etch the PCBs and test everything.

LED driver PCB

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LED mounting PCB (only two lines needed for one frontlight)

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Some of the main components...
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the finished driver PCB:
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test with the 18 SMD LEDs and normal acrylic sheet(1.5mm thick)
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P.S.: Replicas allowed, but NOT for any commercial use.
Last edited by thor17 on January 29th, 2014, 5:11 am, edited 3 times in total.
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Re: Gameboy Color DIY frontlight

Postby st2000 » April 13th, 2013, 8:04 am

Interesting, I've been thinking of something alone these line. I have a bunch of alpha numeric LCDs w/no back lighting and wanted to add some. But not nearly a bright :)! Here's what I have been thinking about:
1. Heat problems. Bright white LEDs generate heat which may shift their color and eventually destroy them. So add ways to mitigate heat problems.
2. Use parts from old LCD panels. Some light distribution materials are really expensive. So making parts from discarded LCD panels may help reduce the cost of a mod.
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Re: Gameboy Color DIY frontlight

Postby thor17 » April 13th, 2013, 10:00 am

Well, if you don't use high power LEDs(1W or more), and there is no need to use them for small LCDs, you don't have to think about heat problems, because SMD LEDs give off heat that can be ignored. Keep in mind, that a standard SMD LEDs with one chip are driven with max. 20mA (3,7V x 0.02A= 74mW).
It's important, to drive LEDs without a resistor, to avoid needless heat. It's better to use a constant current source like I do. Also, if you drive LEDs not with their max. possible current, their efficiency is better and they produce less heat related to their current drain. Less heat, longer LED life! :)
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Re: Gameboy Color DIY frontlight

Postby st2000 » April 13th, 2013, 10:17 am

Well, if you don't use high power LEDs(1W or more), and there is no need to use them for small LCDs, you don't have to think about heat problems


Agreed.

SMD LEDs give off heat that can be ignored. Keep in mind, that a standard SMD LEDs with one chip are driven with max. 20mA (3,7V x 0.02A= 74mW).


Well, just about all our high powered LEDs come to us as SMD parts. And we go to great lengths to mitigate head problems.

It's important, to drive LEDs without a resistor, to avoid needless heat. It's better to use a constant current source like I do.


Yes. Constant current sources. You summed that up well.

I'd be interested in hearing how well the PIC 16F works as a LED power supply. Do post a follow up.
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Re: Gameboy Color DIY frontlight

Postby thor17 » April 13th, 2013, 10:50 am

The big 5050 SMD LEDs have three chips, they produce some heat, and when you use them for LED stripes and use resistors to limit the current, well I guess you got problems, due to the heat of the LED + the heat of the resistors.
But with the 0402 LEDs I use, driven with max. 8mA, I have no problems with heat ;)
BTW, the PIC itself doesn't supply LEDs, not the frontlight LEDs, it just control the brightness by output a PWM signal to the TS19371.
The PIC is just driving directly(with resistors) the bi-color LED that indicates the battery state.
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Re: Gameboy Color DIY frontlight

Postby Osgeld » April 13th, 2013, 5:56 pm

constant current sources give off heat as well (I got a pair of 317's in constant current configuration dropping a few hundred milliamps though a couple of rebels in series, without heatsinks they roll right along at 90c!)

at low powers I doubt either would give off any measurable heat so whatever is best for the design.
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Re: Gameboy Color DIY frontlight

Postby UAirLtd » April 13th, 2013, 6:10 pm

The TS19371 that Thor17 is using is a MHz -frequency switch-mode source with quoted efficiency of 84% (good choice by the way). LM317s are linear, not surprised you're getting a lot of heat.

I like this design.
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Re: Gameboy Color DIY frontlight

Postby thor17 » April 14th, 2013, 3:10 am

Osgeld wrote:constant current sources give off heat as well (I got a pair of 317's in constant current configuration dropping a few hundred milliamps though a couple of rebels in series, without heatsinks they roll right along at 90c!)

at low powers I doubt either would give off any measurable heat so whatever is best for the design.


In your application that's normal, because you're using an analog regulator. If it's running @ 90°C you should use a heatsink.
Generally, for portable applications, I don't like it to use LDO regulators...with the exception of very tiny applications where just a µC has to be supplied that's draining just a few mA.
Also, keep in mind, that I use a step-up converter, like UAirLtd mentioned before, the effiency is a lot better, because it's a switched-mode source.
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Re: Gameboy Color DIY frontlight

Postby Osgeld » April 14th, 2013, 12:32 pm

I know what I should be doing its just an example, I just remember my GB pocket 10 years ago that I got a little stick light for. It was a single white 5mm and a resistor and THAT could wash the transflective screen out
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Re: Gameboy Color DIY frontlight

Postby thor17 » April 14th, 2013, 1:01 pm

The LEDs these days are very bright compared to the LEDs back then...and I use 18 LEDs, I'm pretty sure, that everything will work fine.

Small update, I etched the pcbs and soldered the LEDs, tomorrow I complete the driver pcb.

Image
Last edited by thor17 on April 15th, 2013, 10:11 am, edited 1 time in total.
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