Help: Word Display Circuit

[Marks256]

I thought CMOS ran at 3.3 volts?

 

[Cyborg86]

CMOS ICs run at 3 to 15 volts

 

[Marks256]

That is wild!

 

[Cyborg86]

well, check datasheets of CMOS ICs and you will see by yourself.

 

[k7elp60]

I've done the test for the display with two values of resistors. 680 ohm resistors are suitable for my 7-segment LED display.

I already know how to build the 555 timer to feed the circuit with clock pulses. I only need to know how I can make the binary numbers count randomly so that the message 'Hello' appears in random order.

Thanks,

The attached diagram uses CMOS IC's. The output of the 74AC138 is 8 lines, but you only have to use 5 for your display. You may have to experiment a little on the values of the resistors for the 74AC14 oscillators.
I have shown the connections for the letter O. Use resistors and a PNP transistor for each of the other letters.

 

[Nigel Goodwin]

Just a hint! - don't use JPG for diagrams, it makes them HUGE and low quality, if you use GIF or PNG the files will only be a fraction of the size and perfect quality!.

 

[Marks256]

JPEG sucks... PNG is my favourite... Anways...

 

[Cyborg86]

thanks k7elp60 for your circuit diagram. it is clear enough to read. I will implement it on breadboard and i will tell u later on, if it works or not.

 

[k7elp60]

Just a hint! - don't use JPG for diagrams, it makes them HUGE and low quality, if you use GIF or PNG the files will only be a fraction of the size and perfect quality!.

Nigel,
Thanks for the tip I will try to remember. I have some questions for you in this regard:
How many dpi should I use? I ask this as my drawings are created in a old version of Corel Draw, and I export them to make them internet usuable. I can choose the dpi for the drawings.
Where can I find the software for png drawings? It may already be on my computer, but I don't know. I am using Windows XP home edition.
Thanks,
Ned

 

[Sceadwian]

"The Gimp" is a nice opensource software program for image editing. It's free and there is a windows version which I use all the time. It has a lot of the same features as photoshop, though it's a little buggy for serious work it's great for image conversion and low to mid end editing. And unlike Photoshop's 600+ buck pricetag it's free =)

 

[Sceadwian]

DPI isn't so important, the total resolution of the file is more important. 50-100dpi or so is usually fine, if you want someone to be able to do a high quality prints of it do 300dpi.