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CE Geek - 2022-03-05 11:51 PM
Could be a good tutorial for a CESD if you're willing to write one up, joval.

Yes, I'm in... just need to optimize the power side of things. I ordered the LED strip well over a year ago, it was about $10 but price is a bit high now so I don't recommend getting it from Amazon... there are cheaper units now for much less, however this one the power drivers fits inside the case with slight mod
) so now finally putting things together:
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C:Amie
I would be interested to know what the immediate difference is on the battery life moving from CCFL to Led. One would assume that the saving would be significant.
It does seem counter intuitive that 12v would be min brightness and 0v max brightness.
The LED is just plain brighter so is using slightly more power. Rough comparison CCFL is at best medium bright uses 110ma @12volts, approx 140ma@9volts. The brighter LED strip is 210ma@12volts, 232@9volts using the included LED driver. I measured the milliamps running the Jornada without batteries, powered off my metered bench power supply/soldering station and with screen turned on and turned off
(by toggling the "alt + Calender key"

and subtracting the cpu power useage when screen was off
)
The LED strip has 42 LEDs in series of 3 at a time
(3x3volt=>9volts input
), 5 LEDs per inch
(or 3 Leds per 1.5 cm
). Cut the Strip at the 6 1/4 Inch mark
(has 1.5 cm increments marked on backside
) which gives 30 LEDs to fit Jornada screen including 1/4 for wire connectors. See below photos.
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Thanks Stefan. Yes, I was aware of that LED mod... he made his own strip @ 40 volts and designed his own boost converter as LED driver.
These strips are already assembled with 5 LEDs per inch, in series of 3 so 9 volts... which is a bit high for J720 battery power about 8 volts. Super bright when J720 plugger into AC 12volt supply!
So, yes, I think I need to build a simple custom boost converter to get the best brightness options and it will also allow dimmable. Studying up on LED boost circuits such as this:
https://youtu.be/bJjN_5xed64?t=109
Rich: What happened to all the lonely widows chasing after you... you weren't charged with "assault with a dead weapon... were you??... not again??!!
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dl1av
My biggest concern would be opening the display. I wouldn´t like to get my Jornadas damaged. Are there any screws or is it all self contained with glue?
Small torx screws under the HP and Jornada720 "stickers" at base of screen near hinges, not very difficult, no glue, like cell phone has snap-in plastic catches so technique matters as they break... use fingernail or credit card. Details later or google Jornada teardown.
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fantablium
Nice work, the CCFL's in my Jornada's are not as bright as they used to be so I was thinking of replacing them but LED seems like a better option if a control board can be rigged up especially as it might have the added bonus of improving battery life!
Really doubt much improvement there because once you see a brighter screen during daylight you want the brightness. Most CCFL vs LED use close to same power, IMO, maybe a 20% gain with hi-efficiency LED driver perhaps. Included LED driver is good size to fit into Jornada case but may not be optimized power efficiency. Will explore.
Here are some pictures below.
Joval
Edited by joval 2022-03-07 11:48 PM
(Cut LED at 6.25inch line(red paperclip).JPG)
(LED Driver fits case.jpg)
(30 LEDS fit in 6 inches for J720(680).JPG)Attachments
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Cut LED at 6.25inch line(red paperclip).JPG (203KB - 1 downloads)
LED Driver fits case.jpg (124KB - 0 downloads)
30 LEDS fit in 6 inches for J720(680).JPG (163KB - 0 downloads)