Author Topic: Prototyping an eggcrate control unit.  (Read 1288 times)

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Offline ComeOnDown98

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Prototyping an eggcrate control unit.
« on: August 18, 2020, 06:37:40 AM »
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.
« Last Edit: August 18, 2020, 06:47:22 AM by ComeOnDown98 »

Offline ComeOnDown98

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Re: Prototyping an eggcrate control unit.
« Reply #1 on: August 18, 2020, 06:58:29 AM »
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!
« Last Edit: August 18, 2020, 07:03:08 AM by ComeOnDown98 »

Offline Grand_game2004

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Re: Prototyping an eggcrate control unit.
« Reply #2 on: August 18, 2020, 11:12:07 PM »
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?

Offline ComeOnDown98

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Re: Prototyping an eggcrate control unit.
« Reply #3 on: August 19, 2020, 07:57:32 AM »
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.
« Last Edit: August 19, 2020, 08:02:04 AM by ComeOnDown98 »

Offline ComeOnDown98

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Re: Prototyping an eggcrate control unit.
« Reply #4 on: August 19, 2020, 08:21:47 AM »
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:

Offline ComeOnDown98

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Re: Prototyping an eggcrate control unit.
« Reply #5 on: August 27, 2020, 08:19:38 PM »
Aaaand I finished it Monday, tested it, and...

*buzzer, losing horns*

The damn thing started glitching as soon as I powered it up! :mad:


I tried replacing a few chips, but it still acted glitchy.


Back to the drawing board with me, I guess...

Offline gamesurf

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Re: Prototyping an eggcrate control unit.
« Reply #6 on: August 28, 2020, 12:04:36 AM »
If you do get it up and running, Id be interested in seeing a video.
Quote from: Bill Todman
"The sign of a good game, is when you don't have to explain it every day. The key is not simplicity, but apparent simplicity. Password looks like any idiot could have made it up, but we have 14 of our people working on that show. There is a great complexity behind the screen. It requires great work to keep it simple."

Offline ComeOnDown98

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Re: Prototyping an eggcrate control unit.
« Reply #7 on: September 14, 2020, 01:20:18 PM »
Unfortunately, the board was very glitchy when I tested it...

So, I might have to redesign it with TTL chips...