large 7 segment styal display

Aaron.M.Swope

OK, so I am a high school student at The Academy of Engineering at East Lake high School, and am just starting using parallax chips. I am the Drum Major of the Marching Band, and this year our show's theme is rockets. the beginning of the show starts with a recording of a count down, and I would like to build a large countdown clock. the issue is how. The countdown must be from 10-0

I have a Parallax Professional Development Board, a Propeller DIP 40, SX 28 DIP, and a BS2.

I have no preference of which controller I use, as well as the light source. I also would like to keep this project as cheep as possible.

The requirements are:

1. it must be durable, and able to work every time for 6 shows outside.
2. it must be large enough and bright enough to be seen from the middle of a football field in full sunlight.
3. and it must be able to be set up very quickly.

Thanks for all of your help.

Aaron.M.Swope

I am thinking about either LEDs or standard light bulbs for the light source, but as I said, I am not set on anything

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Aaron.M.Swope

Aaron.M.Swope

My main issue is how to drive the high powered light sources a 100w light bulb for example off of a Microcontroller

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Aaron.M.Swope

HollyMinkowski

"it must be large enough and bright enough to be seen from the middle of a football field in full sunlight."

I think LEDs are out of the question.
Enough LEDs that are bright enough to be seen in blazing sunlight
would cost a small fortune!

I'd make a large clock face sort of thing on a sheet of plywood that was painted white with a single big black pointer that could click
over from position 10 - 0.

I'd put a handle hooked to the pointer on the back of the plywood and mark the positions of the numbers back there just as
they are in front. Then I'd put it at the end of the field where everyone can see it and just stick some freshman back there and
make him move the pointer

But that's just me.....

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep -

HollyMinkowski

Or you could lay out a grid of 100watt bulb sockets on a black piece of plywood
and place at the same location....still not certain if even 100w bulbs could be seen well
at high noon. You could display any number by lighting the correct bulbs, you would save a lot of work if you
just counted down from 9-0 ... other wise you have to have one extra row of bulbs over
on the left to display the number 1 needed for showing the number 10 at the start.

I'd still just wire up the bulbs to one heavy duty rotary switch and have a freshman turn the knob.
Even a freshman is more reliable than a quick project made with a controller.

But if you must use a controller then just use small signal transistors switched on
by output pins to control large relays wired to the bulbs...you could replace the relays with
solid state devices to control the bulbs but you would need several and they would be
expensive I think.

Since it sounds like you are at a fine tech HS there will be at least one teacher there that will have the
heavy duty relays you need in his junkbox...he will also have the heavy duty rotary switch for the
lucky freshman to turn

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep -

Aaron.M.Swope

how would the " heavy duty rotary switch " work?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Aaron.M.Swope

HollyMinkowski

I suppose you would need a switch that can connect both neutral and hot
120vac wires to the bulbs. each position of the switch would then be wired
to the appropriate bulbs to display a number.

You would have one connection from the ac line to the main switch.
The various 2 pole switch position contacts would lead to all the bulbs
needed to light its number.

A veritable rats nest from the switch to the bulbs....better get a 100' roll
of suitably rated stranded wire

Still, any way you go you will end up with some sort of a rats nest of wires.

I say always do things the simplest way, for this project a controller is not
the easiest, cheapest or most reliable way to go. After all this will only
be used the one time, right?

The cost will be the piece of plywood, the bulb sockets, the wire, the switch,
the paint for the plywood and whatever it takes to bribe the freshman.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep -

HollyMinkowski

Better test a bulb against a dark background in the field at high noon before you
start wiring stuff up! It still may not be bright enough. If not, then I strongly
suggest using the big white board with the pointer idea!

The only other way I can think of to make digital numbers visible in sunlight
is to make a white background and make the numbers using small black pieces
of plywood. You would then rig up some sort of contraption to flip the cards you
don't need to make up a number over to a white colored side.

I'll leave how to flip the cards up to you, thinking about it makes my head hurt

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep -

Chris Savage

My suggestion is something I have done in the past when faced with connecting many high powered circuits up to a microcontroller. If you’re using a 120VAC bulb for each segment of your display and you make custom large 7-segment displays you can do the following…

Use an SSR on each bulb/segment (these can be gotten for less <$5.00 ea.) and from the control inputs into the outputs of a shift register. Now you can have a digit pattern look-up table in EEPROM and based on the value of the number find its offset in the table and shift it out to the shift register.

The shift registers can be daisy chained so all data can be output at once and if distance is an issue line drivers can extend the range of the signal wires over twisted pair or Cat-5 cable. This is actually a fairly straight-forward design and is used quite often in such applications. I hope this helps. Take care.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage

Parallax Engineering
50 72 6F 6A 65 63 74 20 53 69 74 65
·

Agent420

I recall seeing a project in an electronics magazine that used those big mechanical 'flip digits' 7 segment displays...· they had partnered up with a surplus supplier and had them available for relatively cheap.· Seems like that kind of display would work well.

I'll browse through my library when I get home, I think it may have been Everyday Practical Electronics or Elektor, but I can't find anything through Google right now...

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

Phil Pilgrim (PhiPi)

I say forget the techy stuff and use an array of humans with hand-carried, day-glo segments which can be flipped up and down manually. You are a marching band after all, right? Think "Beijing Olympics opening ceremony". It will be a very impressive display.

-Phil

HollyMinkowski

I'm leaning way towards a mechanical solution.

I just doubt the bulbs will show up well enough
to make an impressive display.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep -

kwinn

For any light to be clearly visible in sunlight would require high enough power to make battery operation impractical. I would suggest a mechanical 7 segment display using small motors or solenoids to turn the segments. It would require 8 small motors, and a door skin could be used to cut out the segments.

HollyMinkowski

It's pretty low tech but just use some light thin plywood or whatever
and have the numbers painted on. Then have a guy standing behind
and holding the stack, he could simply push each one forward to the
ground thus exposing the next number. I'd affix little handles of some sort
to each board, one after the other, side by side to make it easy
and quick to grab the board and push it.

Make sure the plywood is thin and light or that many sheets might
fall over and squash the guy.... and pray there is not a stiff wind or
the boards might not fall forward too easily. Also don't call out
the numbers too quickly or the guy might fall behind.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep -