Studio 33 - Price is Right Discussion > The TALK Is Right
Prototyping an eggcrate control unit.
ComeOnDown98:
Hey there, beautiful people!
I decided I'd develop a modern driver for Display Systems eggcrate displays... which I have some on hand, as I found a good supplier in Omaha that sells them cheap. :biggrin: $75 a 19S-8 eggcrate digit from the surplus shop is better than $100 a 602L vane digit brand new from ScoreTronics! :dsw:
What I did for my controller design was ignore the use of dollar signs, as some digits, if you try to ground Molex pin 12 to light a dollar sign, would short the 28V supply if there is no dollar sign support.
So, I used a CMOS IC pair... a CD4028 to convert BCD to raw decimal, and a CD4510 to handle parallel inputs, carry, and latching. A CD4511 would branch off to a small LED display for diagnostic purposes, and a TIP127 on each decimal output would invert the signal from HIGH to LOW and handle the high power 28V line. The rest of the electronics run off of 12V. I'd simply run a separate 28V line through a buck converter to drop the voltage down.
Here's an image of how a prototype board is going so far. I just have to wait for the tube of LED displays to come in from China to solder one in and test the board.
Hope you guys like the idea as much as I did!
P.S. I designed this for a custom display using eggcrates.
ComeOnDown98:
UPDATE: I just had a thought...
The 12V side of the board could also be powered from 5V. Say you want to control the displays using Arduino or another microcontroller unit that takes a 5V supply... no problem! That side is rated for between 3 and 15V operation.
The 24V side must not exceed 30V.
And do not apply the 28V line directly to the 12V side. You'll destroy everything that way!
Grand_game2004:
Would the board be able to handle a 'pulse" so if a contestant plays a game like "Magic #" and wins, the amount displayed would flash?
ComeOnDown98:
Well... to make the display flash, there are two ways I could do that...
1: Use an oscillator circuit to pulse the common 28V line, or
2: Use an oscillator circuit hooked to an OR gate to pulse binary data "1111" into the binary input.
I'd opt for the first choice, though I'd probably need to use a MOSFET to handle the large current.
Strobing "1111" through an OR gate would be your best bet here.
I'd like to add that binary values higher than 1001 (decimal 9) will result in blank output on the CD4028.
ComeOnDown98:
UPDATE...
I found a damaged solder connection on a transistor, and... when I removed the old solder, part of the pad went with it! :mad:
But I was lucky and got more solder back on where the broken solder point was, and it stuck even though a bit of the pad ripped. The transistor sits nice and still now! :biggrin:
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