Introduction: LEDs on Pcb

About: retired from electronics and now enjoy inspiring others.

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.

Step 1: Parts and Pc

74hc595 smd INVERTED *SEE TEXT
atmega 328p
ds1302 smd
32.768 crystal 6pf load
16 mhz crystal + 2 caps 22pf
mini usb female (optional)
resistors smd:
5ea 350-470 ohm
6ea 3-5k
6ea 1k
1ea 10k
1ea 50k
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


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

real resistors.

then i install the resistors
then the ics
i cut the 328 legs off at the
skinny point.
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 A2
| | | | | | | | | |
o o o o o o o o o o 5v
- mm-mm-mm-mm-mm-mm-mm-mm-mm-mm--o
o ground

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.....
some hints
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.
good luck
you will need the instructions
on how to program the display
and the many features it has.