ok so you dont want to glue 300 leds
on a piece of glass and then wire
it all up.
so here is a pcb version that works
but you dont get the glass look
and you need to make a box.
Add a Teacher Note to share how you incorporated it into your lesson.
Step 1: Parts and Pc
74hc595 smd INVERTED *SEE TEXT
32.768 crystal 6pf load
16 mhz crystal + 2 caps 22pf
mini usb female (optional)
5ea 350-470 ohm
20+ 0 ohm (jumper)
104pf, 2ea 33mf, 200+ mf
any n ch mosfet smd
Step 2: Start Soldering
my first step is to install the 595
because the columns read left to right
the layout is dictated by this fact.
i tried to change the code but the
display is sharper this direction.
so...invert the 595 to fit the pcb.
turn the 595 upside down with the
legs in the air. I find it helpfull
to mark the edge where #1 pin is on.
take a small screwdriver and push
each leg downward one leg at a time.
now the ic is inverted and lines up
with the pcb pin#1 up and left.
solder a cornner leg first and line
up the other legs. then solder the
opposite cornner leg. then solder
all legs. FLUX makes this easy as
well as a shinny copper pc
Step 3: ROW Ic Is Modified
NOTE THE ROW 595 BOTTOM RIGHT
LEG IS CUT OFF
IF YOU FORGET THIS THERE WILL
BE NO DISPLAY
Step 4: Lost of Leds
install the leds
(any size will fit 603,805,1206,3528)
with the negitave side up.
Usually a green dot or notch.
i have some leds marked wrong so
test them first. with a 9v batt
and a 1k resistor. when the led
lights up the negitave side is up
when mounted on the pc.
the last step is to run a bare wire
across the top pad of the led
so all the negitaves are connected
Step 5: Solder in Other Parts
note.. I solder the jumpers up side down
so you wont confuse them with
then i install the resistors
then the ics
i cut the 328 legs off at the
if you have room in the box
you can ic socket the micro.
there are 3 jumps to be made
3-3, 4-4, and U-U
even I make mistakes...
look closely and see the unsolder resistor.
I spent hours trying to find out
why this board did not work...
then soldered the loose part!!
Step 6: 10 Switches
you need a keypad made of 10 switches
and 10 1k resistors.
this is part of the case and up to
you how to install them. basically
the switches are in a row and each
switch feeds the next through a 1k r
| | | | | | | | | |
o o o o o o o o o o 5v
the A2 input reads the ladder resistor
Step 7: Final Touches
I have an outdoor pc and I sprayed
the entire pc with black paint.
Wait an hour and then wipe the
led tops with lacquer thinner.
i have a IDE usb connector for a
mini usb jack. you can replace the
usb with any connector you use.
download the sketch 'reader_ver_1.2'
every display i ever made did NOT
work when i finished the assembely.
an led is backward, solder splash,
bad foil run.....
if a row of leds are on and only one
or two leds are out then those leds
have a solder splash or installed
backwards. if half of the display
works then usually the data line to
the next ic is bad.
you will need the instructions
on how to program the display
and the many features it has.