LED Sign Board 30X7 - PIC16F628A

[Mike, K8LH]

I would prefer to "scan" the rows to increase duty cycle and reduce "peak" current requirements for full brightness.

You could easily modify and expand your 7x30 circuit using this method;

(1) remove the current limiting resistors from the row pins.
(2) install row driver transistors. you'll only be driving one row at a time.
(3) use 74HC164 or 74HC595 or similar 8 bit shift registers for the columns.
(4) drive the ULN2803 sinking drivers from the shift register outputs.
(5) install current limiting resistors on the ULN2803 outputs.

Actually, you'll probably want to use row driver transistors for every 10 or so columns unless you install some very "big" transistors (grin).

I would actually use 8 bit serial-to-parallel sinking driver ICs for the columns instead of the dual IC combo' but they're expensive. For the dual IC combo' I guess I would choose the 74HC595 over the 74HC164 because the '595 has a latch which would allow us to take our time loading 100 bits of data into the shift registers without messing up the display. The '595 also has an output enable pin which could be driven by a PWM signal to control display brightness.

Regards, Mike

[Mike, K8LH]

With the very good brightness you're getting on your 7x30 display with only a 1/30th duty cycle, I am thinking that you might actually have several different options for an expanded 7x100 version. Perhaps you don't really need to use 13 74HC595's and 13 ULN2803's for a 1/7th duty cycle 7x100 display.

Let me think about this and get back to you Sir.

Mike

[Gayan Soyza]

Master are you there!

Ah yes that 74HC164 is one of my favorites & I have done some few boards using that.I have attached one of my PCB layout done in past.

I'd like to do a row scan to a large column displays.

Thanks for your information.

A bit off topic what you doing these days sir?

[Magen]

Hi Gayan,
That's a nice display. What Led's did you use? I am trying to build a sign just like it.

[Gayan Soyza]

Hi Gayan,
That's a nice display. What Led's did you use? I am trying to build a sign just like it.

It’s a type of super bright LED designed for signboards.

Forward current 20mA (operating below that with the same brightness)
Forward voltage 1.9V
Viewing angle below 30 d.

Actually there were no many that type of LEDs in my place so I have to shift to a ready made MATRIX.

[Magen]

Hi Gayan,
Where did you purchase those leds from? Do you have a part number or something for it? Or even a link to a website?

[Bolaji]

Master are you there!

Ah yes that 74HC164 is one of my favorites & I have done some few boards using that.I have attached one of my PCB layout done in past.

I'd like to do a row scan to a large column displays.

Thanks for your information.

A bit off topic what you doing these days sir?

Gayan,
I have interest in building LED Sign Board that is scrolling led display(Like the one you posted 9th July 2008), has a project kindly help me with materials to use and how I can go about it. What I want the Sign board to display the Message "WELCOME TO SCHOOL + arrow". Gayan, I will very happy if you can assist. Awaiting your replay, Thanks.
Regards
Bolaji

[Gayan Soyza]

Gayan,
I have interest in building LED Sign Board that is scrolling led display(Like the one you posted 9th July 2008), has a project kindly help me with materials to use and how I can go about it. What I want the Sign board to display the Message "WELCOME TO SCHOOL + arrow". Gayan, I will very happy if you can assist. Awaiting your replay, Thanks.
Regards
Bolaji

If you have experience with PICs I can give a hex file with a message "WELCOME TO SCHOOL + arrow"

[Bolaji]

Gayan,
I do not have experience with PICs.

thanks
Bolaji

[F877]

Can you provide a schematic?

[F877]

thanks
have interest in building LED Sign Board that is scrolling led display

[F877]

That's a nice display
thanks site

[ameryknu]

can you provide us some schematics...i'm interrested about how to made a signboard...thanks

[bernal_john]

is there anyone who can help me with my project? it's actually a 30x7 LED array display. and im using discrete LED's. and im just using a microcontroller which has 16 outputs only... what IC will i use in order to drive or to aid my array display???

[deansmith]

Gayan Soyza, can you post a schematic and hex or asm file for pic16f628 please please pretty please. Or tell me where i can find a scrolling LED tutorial useing a 16f628 and .asm