Chest display project


New Hunter
I'm considering making up a chest display and wanted to run it by the group before going off in the wrong direction. The main thing is that I need a smaller one for my kid's costume so I kind of have to do it myself. I came across these really tiny displays that look just about the right size. So, I'm getting jazzed to do it.


7S-1, Super Tiny 7 Segment LED Display, Red, Common Anode, RH DP 7S-1 - All Spectrum Electronics

I've searched around a bit and only came across the TK409 display. I'm pretty sure I can build the circuit for that pattern but I wanted to check and see if this is the exact pattern the production suit uses. Does anyone have an example of what the actual display does? If I'm going to spend the time on it, I'd like to make sure it's right. If it's exactly what the TK409 one is, that should be a piece of cake.

Once I get this done, I'll post all the information - parts list, video, schematic, PC board printout and some instructions. Who knows, maybe even offer pre-made boards or something. The parts would be peanuts - less than $20 I'd say minus the PC board printing chemicals. This site has been so much help so far, I'm hoping I can throw something into the mix. I did logic design in school and built circuits and printed circuit boards and still have my kit with basic parts and a breadboard. I'm a little rusty but I'm raring to go.

So what do you guys say? Is this something that would be useful? Anyone know the exact pattern the original uses?



The bike light route is the path to the dark side. Quicker, easier, more seductive... and much cheaper, too! :D

But if you can provide a thinner, more compact alternative, I'd be very interested, provided it didn't cost more than, say, $30...
Ha! Yeah, now you have like 2 of them right? I cannibalized a tiny key chain light for the rangefinder which worked out pretty well. Well, I'm going to doing something or another at least for the costume I'm working on and will share whatever comes of it here. The TK409 video will be the basis for it but I'm guessing that's not the exact blink pattern so maybe we'll play with it a little. This is the video:


The pattern is pretty straightforward. The upper lights are a sequence with the lights arranged out of order and the number display is actually just some segments always on and others just going on and off. This could easily be jazzed up to have a more complex sequence with the same circuit wired a little differently.

The foundation of the circuit is this "decade counter" which does a simple sequence of lights - up to 10:



The main modifications to this would be:

  • Change the number of lights to 5. To do this, you only have to take away some LEDs and tie that Rst (reset) pin on the 4017 chip to one of the later outputs in the sequence. The TK409 sequence seems to include 2 counts with nothing lit so that would mean wiring 0 - 4 as lights then 7 (maybe 6) to Rst.
  • Make the display light pattern. For this, you would wire the display up with the appropriate resistors then tie the always on segments to positive and the blinking segments to Out from the 555 chip. To improve on this, you can tie some other segments to outputs from the sequenced lights. This is easy on the breadboard. Or, to get really fancy, you can add other chips that would let you do "ORing" so that segments can light in this stage of the sequence OR that stage. You really can do anything you want if we can get a lead on the correct sequence.
  • Adjust the speed of the circuit by changing the resistor and/or capacitor on the 555 timer circuit. I may set this up with an variable resistor so it can be tweaked.

So, unless someone comes along with a definitive answer on the exact sequence, I'm thinking about doing the one on TK409 with a little variation on the number displays.

I'm not really planning to start selling things or anything - really want to end up with a totally self-service project. "Order this, that and the other from this place, use this little tutorial to solder it up (some parts are directional based on polarity), here's some variations, etc." Maybe just manufacture some of the boards since there is a bit of an outlay for the etching chemicals. I know if I had a parts list and a board to buy, I'd be a happy camper right now. But hey, projects are fun too.

The thickness may be tricky. Can't do much about the size of the displays and LEDs. I am thinking about designing the board in such a way that you can have some options like:

  • Cut this trace and solder in a switch if you want one.
  • Cut the board along this line and you can relocate the chips and run a wire between the controller and light board.
  • Use these extra holes to change the pattern of the displays.
  • And, an alternate board with a layout for those tiny displays above.

Based on the circuit above, here's some sample prices I see in the Jameco catalog:

  • 4017 chip - $.45
  • 555 chip - $.25
  • Rectangle LED - $2.97 for 30 (minimum order)
  • 7 Segment display - $.99 (need 5 so $4.95)
  • Unprinted circuit board - $5.49
There would be a few more little parts like resistors, switch (if you need it) and battery holder. I'm going to run a cord from mine to the jet pack which already has 6V so I won't need either of those. Anyway, that's about $15 right there.

The main thing missing there is circuit board printing chemicals which in the smallest quantities are about $22. Oh, and $2.50 for a couple tiny drill bits. Still not bad at all.

If you're like me and want to learn to do as much as possible, you may want to consider doing the circuit board etching yourself. I did this at school in the early 80's with professional shop size stuff (like a really cool bubbling acid bath!) but these do-it-yourself kits look totally manageable. Take a look at this video on PC board etching:


So, that's pretty much the plan. I think it's totally doable and worthwhile so I'm going to order the parts tonight and try to get the circuit up on the breadboard a few days after they come. I'll try to post a video. Sure hope someone can point out the actual sequence.

Update: Got all the parts in the mail and the circuit on the breadboard AND the transparency for the circuit board (micro display model) but just need to get some things for the developing and etching. This circuit will be a lot like the TK409 version but In looking through some photos of the real costume, it's clear that there are more numbers displayed. If anyone has footage of the original display, I'd be happy to make the circuit that can do that sequence for the adult size display version. I am going to investigate low profile displays when the time comes.
Well, I got the micro version done. Had some bumps along the way but the final working article sure looks cool in the little guy's costume. At least mocked up as it is now. I still need to get a lens (anyone know where to get one?) and the actual mounting done but the tiny display is fun. It's only 1" wide and ends up fitting almost perfectly in the slots I already had cut. Really lucked out there. I'm going to widen them a little and hide the traces a little better but the display is a lot brighter than it shows in the photos.



I flubbed the PC board etching and had to save it with a little carving of the remaining traces. Not 100% sure what I did wrong but the developing seemed to go pretty well. It was clearly readable. My original mix on the etchant was too thin so I had to redo that so maybe that was the issue or that it wasn't warm enough. Not sure but I'll try it again sometime.

That's one ugly PC board but it works!

The actual circuit worked as expected but I had one missing connection that I had to wire and a short that was caused by the bad etch. Not bad - it's a prototype. I fixed the artwork and actually shrunk it enough to do two boards from one 3" x 4" blank but I don't know if anyone really needs the micro display.

To make up for the height difference in the displays and the LEDs, I used a separate board with some soldered wire as posts. The wires are part of the circuit. Soldering those tiny display traces was a real trick!

So I'm not seeing a whole lot of interest here but I think I may still do the kit. It's really not that expensive and I'd like to see it through. So, I think I'll take this circuit and light pattern and change it for use with a full size display. If anyone wants the details on the micro version, just let me know and I'll post everything here. If anyone knows the real light pattern I'd be really excited to make a fully correct one. May tinker with an actual random number generator anyway though since I see several pictures with different 5 digit numbers on the display.

Here's a movie of the micro display mocked up with the armor piece. Still need to get a red display lens, do some shielding so each light doesn't light up the one next to it, mount the thing and widen the slots a little.

Awesome project you have here! I'm sure there will be some interest on this (for the small and the original size). Work well done!
Well I like it. I have been putting together a similar project and got mine to work very well, but I have a lot more parts in mine, mainly a resistor between each LED and segment, without the resistor I found the LED's would get too hot and simply burn out. I would be interested in one of your units for sure.
Keep up the good work
Thanks guys. Hopefully when it's all packaged up, this stuff will be useful to others.

Yeah Mike, the resistors are needed for sure. I learned my lesson as a kid tearing apart calculators and stuff. That's what got me thinking about the micro displays for the costume. How many resistors and the values needed all depends on the patterns going on with the display. If they're doing the typical number displays then you really need one for each element or things go bright and dim based on how many segments are lit. The nice part about this little circuit is that the display is only showing two patterns. So, I just used two resistors for the displays - one for all the segments that are always lit an another for the ones that flash. These have a command anode (+) so I ran that direct to positive 6V and put one resistor to ground for the always on and the other to the clock output from the timer.

For the LEDs, I got away with one on the common cathode (-) since there would only ever be on light lit.

Been having fun with this stuff. Really wish I knew the exact sequence but after spending some time in the gallery, I have a few examples to work from:


A few observations:

  1. The lights above the displays are multiple segments (4 per display) and I'm guessing they are these LED bars:


    There are 10 to a bar so it would take exactly two of these to make the number needed for 5 displays. The size works out too. The displays are 10mm wide so that's 50mm total plus a little space between. The LED bars are 25.27mm wide so that's a near perfect match.

    The displays:


    So, I'm going with these for the full size displays.
  2. There is a time where the light bar goes blank.
  3. The displays are sometimes regular numbers, sometimes what looks like letters and sometimes cryptic lines.

I'd write-up the micro display but I want to add a few things to it. The one I have for my kid's costume works great but I'd like all of the versions of this to have:
  1. On board switch option that could be reached right under the armor plate.
  2. On board battery option (2 coin cells).
  3. Power cord terminals this would allow for running a cord to a larger battery and I'm thinking that if there are people out there that display their costumes on a mannequin, they could have this be removable. The circuit could run of either battery or power cord.
  4. Speed adjusting resistor (in parallel with one of the existing resistors)

So, I'm working up another parts order and when I get the stuff back, I'll work on a full display setup using the same circuit as the micro display but with full size display and the features above. If the battery and switch work well, I'll update the circuit board for the micro and writeup both of these with the circuit board printouts and parts lists.

Then, I really want to get fancy with the displays and try to get something where there are multiple patterns shown rather than the alternating two. That's going to take more chips for sure so we'll see how that goes. I have a couple ideas on the circuit design but we'll see how it works out. It would be great to just get a memory chip and program in the exact patterns then have a counter run through the elements in memory.

Hopefully that next board etching will go a little better!
Those parts are exactly what I am using.

I have the sequences somewhere, can't remember off the top of my head, for both the LED and display, I'll post them for you.
I did my own research on the chest display and its sequence and I got these results:

The digital characters used are this type (with approximation) and not the squared type used by others:

Chest Display Character.jpg

I used for my sequence the carbon chamber scene and I gathered all the awailable images from the Gallery and the result is this:

Chest Display Sequence.jpg

Then I drawed a separate image for each sequence and after watching the sequence frame by frame I got this time period for each sequence:

Chest Display Sequence Mine.jpg

Note that the first and the last sequence's time is approximated, because the whole scene with the visible chest display is not full and these two sequence parts are cut. I also didn't used other sequences because it's hard to tell where these belongs in the whole process.

And this is a GIF file with the timed sequence:

Chest Display Sequence.gif

I hope this helps.
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Great Stuff! That helps a lot. I can really work with that. So it looks like the sequence goes at about 1/2 second and the off cycle is almost twice that. I'd have to go with twice since it's a lot easier.

Excellent catch on the display style. I've been looking around for the ones with the slanted edges and so far what I've found is pretty expensive - like $3 per display as compared to the $1 squared ones. But that's only $10 more so not really a big deal. I think these may work well:

HDSP-7503 Avago Technologies LED Displays

They advertise "mitered corners" so that should be correct. The pinout is different from the cheap square ones I ordered so I'll work on the sequence with the ones I have then adjust the wiring for the better looking ones.

Getting that sequence may be a little tricky. I can see it being either based on gates or trying to use a memory chip with the patterns programmed in. I haven't worked with memory chips before but I think I can work it out. The nice part about the memory chip method is that the memory chip stores 8 bits (1 byte) for each digit stored which is almost perfect for the 7 segment display. You could literally program at the single segment level and do whatever you want in the programming of the chip.

The hard part is that you can only get one byte out at a time and we need 5 so we'd have to have a circuit that moves those bytes around and stores them before passing them to the displays. More chips. Also, you'd need to have the programmer for the memory chip which is like $40 or so.

The other way based on gates would be easier to workout but once set, it would be wired in that way and it still may end up with a fair number of chips. If the number of chips goes up, we may end up with

This is great though! Thanks for the information. I've got some parts on order which should be here in a couple of days. I'll work on the logic for the gated circuit and see how many chips that would take and think more about the memory chip version.

These are the two sequences I have, not sure where they came from, but thank you to the original poster, no where near as detailed as what RafelFett posted though.
This sequence is easy to replicate.
I use a 4017C that give me 5 outputs for the 5 LEDs plus a 555 timer to control the sequence. I then use the same 4017 IC for the display to flash on/off. This will use 6 of the outputs of this IC. The display is also wired constant on. The speed regulation of the sequence is controlled by resistors and a capacitor at the timer IC.
As mentioned I also use resistors between the circuit and the display. So the trick here is to get it to flash a different sequence, so maybe use one of the remaining pins on the 4017 IC? I will have to check out the actual pin configuration but I think there are 4 surplus pins that could be outputs. And also determine if any of the constant on's must be switched off so they then become part of the flashing circuit.

These are the two sequences I have, not sure where they came from, but thank you to the original poster, no where near as detailed as what RafelFett posted though.

I have the same sequence saved from the TDH Wiki before it was upgraded and lost. I think, but not sure, it was made by Art.
I like that sequence there better than the one I did for mine. Yeah, that's pretty much the easiest way to do it is with the alternating of the displays.

Good news, I drew up the logic chart for the "Rafal Works Sequence" (RWS) and it's not bad with gates. Not bad at all. Works out to an additional 4 chips and an added cost of only $3. There will be more resistors since there are more sequences but I'm going to look into those DIP packaged resistors. Might save some space. Lucked out with that sequence since there is a lot of repeating logic. I think it came to less than 10 gates in the end.

Yeah, it would be just an add-on to the 4017 circuit with the gates all tied one way or another to the first 7 outputs. The nice part is that the number shift will happen as the LEDs change rather than the alternating between the LED changes. I just called the parts place and I'll be able to add the parts to the order tomorrow morning. With that stuff, I can at least get a prototype on the proto board. Also plan to put in an order for those more accurate displays. I'll run everything by you guys before committing to anything. I want to make sure that the final product is as accurate and usable as possible.

Thanks a lot for helping on this!
I'm not nearly smart enough to contribute to the electronics design part of this. But, one thing I've always wanted as a costumer was for the portion of the display in the chest to be very minimal. Just a small board with the LEDs on it. Then have a cable that runs down to, say, the belt pouches, where the main board would be. Then the board could be in a project box, rather than just loose.

I've had chest lights get damaged by sweat, plus I always welcome smaller components in the suit.

I forget who made mine, but it's 2 boards connected by a ribbon cable. Not exactly my dream setup, but close :)
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