Author Topic: Prototyping an eggcrate control unit.  (Read 3162 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:
« Last Edit: January 11, 2021, 05:11:26 PM by therealcu2010 »

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...

Offline tomcat

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Re: Prototyping an eggcrate control unit.
« Reply #8 on: January 09, 2021, 12:32:30 PM »
I did something similar to your project, using a 12V LED power supply, boost controllers, inexpensive relay boards and ESP8266 microcontroller off of Amazon.

The great part about using the ESP8266 is the customization. You can shut either digit off, flash the digits, and have them count down and count up. Pretty much whatever you can think up.

Check it out!

Edit: I guess I'm not allowed to post external links yet. Go to Youtube and search for "Actual Display Systems 19S-8 Vintage Eggcrate Display (Light Bulb Matrix) - Countdown Timer"

Offline MSTieScott

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Re: Prototyping an eggcrate control unit.
« Reply #9 on: January 09, 2021, 04:17:33 PM »
Am I allowed to post links or YouTube videos?

<a href="http://www.youtube.com/watch?v=vT07cAo9s-w" target="_blank">http://www.youtube.com/watch?v=vT07cAo9s-w</a>

There it is.
The statements and opinions expressed above are those of the author and do not necessarily reflect the opinions of the author's employer or any company the author has worked with, past or present. Please maintain 6 feet distance.

Offline price_authority

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Re: Prototyping an eggcrate control unit.
« Reply #10 on: January 11, 2021, 10:58:06 PM »
I've built readouts like these before.

One way to do it is to use 5 PROM's to generate your columnar dot patterns. Then use ULN chips to drive the lamps.

You would need a PROM burner.

The 1820 lamps at 28V are way too bright and way too hot. They cause the foam-rubber holes to deform. You're smart to use 12 volts. I would look for LED's to replace the incandescent lamps. You can use TTL chips to drive the PROMs.

If you want to get fancy, you could multiplex the five columns and use only one PROM to generate the columnar dot patterns. That will lower your chip count. I don't recommend this for incandescent lamps but it might work OK with LEDs.
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Offline price_authority

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Re: Prototyping an eggcrate control unit.
« Reply #11 on: January 11, 2021, 11:06:00 PM »
If you want your display to flash, you need to do it at the controller level rather than at the individual digit level.

Say you have three or four digits. You want all of the digits to flash synchronously and this would have to be done at the controller that controls all of the digits. If not driven by a central controller, the digits will flash in a random asynchronous fashion and it will look quite weird.

Your controller can perform arithmetic, flash the digits, act as a countdown clock, etc.

I will look in my notes at home and see what components I can recommend.

One idea for making the actual display: Take a thick slab of white plastic and make holes in it using a 3D printer and paint the face black and use it as the mask, or use a second, thinner layer of black plastic with matching holes. Then you would make a PC board to hold the lamp sockets, diodes and whatever. Use LED's to keep the heat down. The holes are 5/8" in diameter.
« Last Edit: January 11, 2021, 11:14:31 PM by price_authority »
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Offline price_authority

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Re: Prototyping an eggcrate control unit.
« Reply #12 on: January 14, 2021, 02:48:46 AM »
Here is an LED replacement for the 1820 lamp.

NOTE: YOU WILL NEED TO ADD A CURRENT-LIMITING RESISTOR.

https://www.amazon.com/dp/B083ZK1T99/?coliid=I11S3MMG5E5DLL&colid=BUK1DQLOWR4B&psc=1&ref_=lv_ov_lig_dp_it
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Offline Sizeman

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Re: Prototyping an eggcrate control unit.
« Reply #13 on: January 14, 2021, 01:05:08 PM »
Here is an LED replacement for the 1820 lamp.


I'm curious to see how one of these units looks with a full set of LEDs, although it's still pricey to re-lamp/modify.
It's not something I'd be doing with my single unit which needs a controller to operate. I thought about purchasing a few more but mine arrived with some damage, so I'm hesitant to buy additional ones.

Offline tomcat

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Re: Prototyping an eggcrate control unit.
« Reply #14 on: January 14, 2021, 01:09:43 PM »
I plan to keep mine with actual light bulbs as that's part of the fun and nostalgia of the eggcrate display itself.

There's a guy on Reddit that made an eggcrate display with RGB LEDs so it can display multiple things. Really cool project!

Search for "Remember that eggcrate display I built a couple reddit" on Google.