• Final assembly

    lion mclionhead • 09/23/2022 at 04:09 • 0 comments

    Wiring all 14 segments reminded lions of why no-one builds large LED panels even in China.  The 2 heroineclocks were the most complicated displays.  When the 14 segment display was wired, the younger lion still had 12 segments to go.  Those older displays took multiple days.  The younger lion was like the other hikers who still had 12 miles to go. The modern wrapping wire is much easier than the ribbon cable of old.  Even though it entails routing every segment separately, it's easier to wrangle & fit in the space.

    Ran the LEDs at 8.4V per segment or 2.8V per LED.  Maximum power is 1.5W.  The AHT20 had to be mounted upside down to keep humidifier deposits out of it.  The sensor seems to be slightly too low, but it will never be viewed from above.

    Without paint & with the whiteout being manely flaked off, there technically must be less even lighting, but it's not very obvious.  The diffuser cuts through tape & is very brittle so we'll see how long it lasts.  A diffuser from a recycled LCD monitor gave maybe a hair more diffusion than wax paper.  Must remember if a neighbor ever throws out a TV again to try to recover the diffuser & fresnel lens.  Another alternative to rustoleum might be white nail polish.

      The blue numeric display looked like cracking a light stick for the 1st time.  The same eerie blue from mid 80's july 4 blazed forth in unparalleled glory.

    LEDs were previously too expensive to use anything but red, but now that blue is 7 cents per LED, it's time for more colors.

    https://www.amazon.com/dp/B01AUI4VYW

    The 1st LED panel was 28 cents per red LED.  

    It's much brighter than the other panels at 8.4V per segment.  Between 8 & 8.4 is where it overpowers the room lighting but doesn't turn night into day.  At under 1W, maybe lions have to get used to sleeping in daylight.

  • Death of an LED panel

    lion mclionhead • 09/20/2022 at 00:05 • 0 comments

    The lion kingdom previously painted its LED panels with a 20 year old 8 oz can of glossy white rustoleum.  When that dried out, spray paint seemed like a good idea until it completely dissolved the foam core.  This warped, dissolved panel was basically a loss, but there was still an attempt to salvage it & the paint by hot gluing all the voids left by the dissolved foam & spray painting on the hot glue.  The smallest can of paint is now $22 & 32oz.  The 8oz cans are no more.  The spray paint was $7.

    The spray paint couldn't achieve a thick reflective coating without going outside, suiting up, & getting paint everywhere many times.  Any exposed edges of foam were completely dissolved.  This board already wasn't very appealing in its warped state.  Now with the foam dissolved, it wasn't worth proceeding with soldering 42 LEDs.

    Thus began a new LED panel with whiteout instead of paint.

    What has become the standard display size has lines in freedom units because those give the roundest numbers.  The vertical lines are drawn 1/4" thick even though the foam board is really 3/16" because it's easier to measure.  The digits are 8 3/4" tall, 6 3/8" wide.  The segments are 1 1/2" wide.

    Vertical 1/2" tall pieces go in 1st, with convex side facing down so it causes the panel to bend concave instead of its natural tendency to bend convex.  All 1/2" pieces are cut with scissors in the short direction & xactos in the long direction.  The longest piece which can be hot glued in 1 go is 8 3/4"

    Then the horizontal pieces are cut to the remaneing size & glued in.

    Sadly, whiteout was a subjective failure, cracking the moment it was applied.  Oil based rustoleum never had any problems.  The total cost so far has eclipsed the cost of a roll of white PLA & it looks worse than PLA.  A roll of PLA would definitely be cheaper than a  32oz can of rustoleum.

  • Death of the LCD panel

    lion mclionhead • 09/19/2022 at 04:54 • 0 comments

    The LCD hygrometer from May was useless because it was too small & it was unexpectedly being used a lot more than expected.  The humidity was expected to be very constant near 25%.  In reality, it varied from 20 - 55% by the hour.  The decision was made to make another large LED panel.  At least it showed 2 small LCD panels could be stacked to make a less small numeric display.

    For this panel, the exact foam strips to be used were colored in different colors.  Colors changed as various 25 year old highlighters died.  Does generation Z even use highlighters?

    Lion tip: swing the monitor out of the way to free up more room.

    Vertical strips were cut 1st with scissors & hot glued with glue applied to the paper side 1st.  Then horizontal bits were cut exactly to the right size & glued in.  Being an ancient posterboard, it was warped into a picture tube.

    Being a used PIC18LF458 from 15 years ago, the bug in this one was the MCLR pin requiring a switch to program it, otherwise it would show read failures.  There is a spot for adding an XBee for transmitting humidity readings to a humidifier.  That meant the PIC ran on 3.3V.  The clock was a recycled 4.1943 Mhz crystal.

    The next task is waiting for the slow boat from China to bring LEDs.