Building 2 digit up/down counter LED display

Discussion in 'The Projects Forum' started by izon, Mar 17, 2013.

  1. izon

    Thread Starter Active Member

    Mar 17, 2013
    Hi.. newbie here so pardon the ignorance.
    I'm looking to build a 2 digit up/down counter that has a rather large LED display. This is to be used in an office setting so staff can see by the displayed number how many are waiting to be seen. The receptionist would push the up button as more clients arrive and the down button as the number decreases. Also a reset would be handy. There is no need for audio tones to signal changes. The 2 display digits should be 12-15 inches tall and preferrably green in color.
    I have seen a commerciallly available product that is very close but has some additional features that are unnecessary and would add to cost.
    Here is a link to the one I found so you have a better feel for what I am needing.

    Here is link to a site I found that has pretty much everything for circuitry but I would need the large display and the way to integrate them into this circuitry.

    Thanks for any help / advice. As usual, we would like to keep the cost at minimum... and on the display, it would be great to have an enclosure method like the finished product link shows so that it could be hung from the ceiling or mounted to a post.

    Thanks again!
  2. crutschow


    Mar 14, 2008
    A 40110 is an up/down counter with a 7-segment display decoder output so you could use two in cascade to do what you want. You may need to add a transistor driver on each of the segment outputs if your large LED display require more current than the 40110 can provide.

    Edit: As far as the display, a Google search for large LED displays should help you find something appropriate.
  3. elec_mech

    Senior Member

    Nov 12, 2008
    Welcome to AAC.

    This sounds a lot like a circuit request I did for a Nuts & Volts reader a couple of years ago.

    Attached is a schematic which should meet your needs nicely. The biggest expense will be the display due the large size you're looking for, but you can make your own for a lot less. I've attached a picture of something I did on a 12" x 12" piece of PVC with red LEDs. The digits are 9" tall.

    The circuit uses a $10 RC car to act as a wireless controller, otherwise you'll need to run about five wires from the controller to the display.

    Several items could be left off depending on you'd like to do:
    • U4 & U5 act as an auto-repeat - if the up or down button are pushed once, the display will advance by one digit. If either button is held down for a second or more, the display will advance rapidly.
    • U1 and all parts connected to it as well as Q2-Q5 can be left off if you plan to wire the buttons to the display (as opposed to a wireless option).
    • Q1, U6, & U8 flash the display. The reader wanted employees to know when they couldn't afford to spend more time than needed with customers. If not needed, you can leave these off.
    • If you make your own display, I'll suggest a different IC for U9 & U10 (less expensive).
    You can program a microcontroller as shown in the second link you provided. I'd suggest putting a ULN2804 or similar between the PIC and the display to handle the larger voltage and current required by a larger display.

    What is your experience with electronics and microcontrollers?

    I'll help you if you'd like (as much as I can anyways) - let me know how you'd like to proceed.
  4. izon

    Thread Starter Active Member

    Mar 17, 2013
    Thanks crutschow for your help....I appreciate your input!

    To elec_mech : Thanks very much... I believe you have pretty well
    "nailed it" for me! Awesome ! I haven't had much time to look at your entire post so this will mostly be a BIG thanks reply and appreciation for your offer to continue to help me with this as I trudge along.

    I've been an electronics tech all my life, self employed in consumer electronics repair... dealt with a variety of service work on TV, VCR,
    sound systems, CCTV, and a lot of Dish Network Satellite installs.
    I'm not at all familier with details of microprocessors or their progamming.
    Several years ago tried to "bone up" on digital at a local Vo-Tech school but that was just the basics and a long time ago.

    I would certainly consider building the display boards myself and may like some suggestions on how to "house" the two panels to have them look something like the link I sent of the commercial available product. You
    say you built them out of PVC... do you mean something like "Plexiglass"?
    Well I would like something that is not transparent to place the LEDs on.
    So ... not quite sure what material I could use... and where would you locate this.. a building supply place like Lowe's or Home Depot?

    I assume I could chose green LEDs for a display..... which may cost more.

    I'm going to have to review your comments about the circuitry. Also... no I wouldn't be able to actually "program" anything I don't suppose. I guess that circuitry link I sent would require progamming so that may put me out of using that particular circuitry.

    The schematic seems pretty involved... several ICs. Sorry for the ignorant question... why does yours have so much more to it than the single IC version in the diagram I linked to? I know you mentioned the optional items and since I don't know how to include your text as "quotes", I will paste them below and insert italic underlined comments:

    • U4 & U5 act as an auto-repeat - if the up or down button are pushed once, the display will advance by one digit. If either button is held down for a second or more, the display will advance rapidly.
    • I don't think we would need this function.
    • U1 and all parts connected to it as well as Q2-Q5 can be left off if you plan to wire the buttons to the display (as opposed to a wireless option). This would be a great benefit to include for ease of location.
    • Q1, U6, & U8 flash the display. The reader wanted employees to know when they couldn't afford to spend more time than needed with customers. If not needed, you can leave these off.Here again,probably will not be needed.
    • If you make your own display, I'll suggest a different IC for U9 & U10 (less expensive). Yes I would like to make the display so your suggestions would be great to have.
    I don't want to put you through a lot of work at this point but would it be possible to have you modify the schematic to reflect changes (not needed features) I would pointed out above? I would likely get confused on exactly what devices to remove and how the schematic would lay out with those changes.

    You mention controlling this with just a $10 RC car... well I don't know if they are just $10 but can you point out (on the web?) exactly what you mean here.... so on the remote a steering move perhaps would cause either the up or down funtion to move... any chance to make this "reset" to zero on the remote. What in the original circuitry in your link would do the "receiving" of this remote signal? ... and the antenna? Would you expect a 20-25 foot range? Guess I haven't messed with those items so not sure.

    Well that is more than enough to burden you with for now... I'm really excited that this could be built and at a reasonable cost... another hurdle would be (after it is scaled down to only required funtions) how to construct this on a PC board... I do have lying around a "breadboard" from when at the tech school... a plastic unit with many rows of holes to place wires into and I think it has at least a 5 volt supply but will have to "dig" it out to check.

    Many thanks!:)
  5. elec_mech

    Senior Member

    Nov 12, 2008
    Ah, then you've got more hands-on experience than me. This should be a cinch. :)

    Plexiglas would work - I didn't get into details last night as I somehow lost my original post and had to quickly retype before dinner. If you opt for that, just spray paint it to lose the transparency.

    I use PVC. I haven't had luck finding it locally, so I usually get it from McMaster (8747K112) or Enco. You'll need it in a larger size, these are just provided for reference.

    Before you do that though, note you'll probably want a filter. Take a look at the picture from my last post. Notice the digit on the left, while visible, is a little hard to see and that you can clearly see the unlit segment which makes reading the display a little difficult if you just take a quick glance at it - which is what most people will do. Now look at the digit on the right - clear, easy to read, hard to see the unlit segment unless you're really looking for it. This picture was taken in my shop with the fluorescent lights on. Now, if you take a look at the link you sent for the "commercial" product, you can read the 87 on the display, but it's a little tough. They appear to have just put a piece of clear acrylic or glass over the segments, but no filter. Take a look at an alarm clock with a red or green 7-segment display. If you look closely, you'll see that the digits are behind a colored piece of plastic (dark red or green depending on the color of the digits).

    This is what will really make your project stand out. I mention this now, because you can buy a filter (read: cheap piece of colored acrylic) and the PVC from the same place and save on shipping. PVC here, green filter here. You certainly don't have to use PVC for the backing though - acrylic can work if you paint it (easy to crack when drilling though depending on what you get) or even thin plywood. PVC is easy to machine and holds its shape well which is why I like it.

    As for a commercial-looking case, off the top of my head, you could use a shadow-box from a crafts store like Michaels or AC Moore if you can find one big enough. Replace the glass with your filter. I made a simple one for a counter many years ago using something like 1x3's and molding for the front. Picture shown below. This was before I really knew about filters, so it just has a clear piece of acrylic over the digits (sigh).

    Yes, you can easily use green LEDs. No, they will not cost more than red. Red, green, and yellow all run about the same given the same output. Blue LEDs are quite a bit more - but they look so cool. You'll want diffused LEDs with a low mcd (millicandella) output, something around 30-300mcd. We'll broach that at a later time.

    I understand - it looks a bit intimidating, even to me. :eek: I like features and this circuit is choke full of them. The biggest reason for the difference between mine and the single IC solution you posted is the latter uses a microcontroller (uC) which is programmed to do whatever you want - it can take the place of several ICs because it can be programmed to do a variety of tasks. I'm using discrete logic IC's which each serve a specific, individual purpose.

    However, at the heart of it all, mine uses two ICs while the other uses one uC to handle counting and displaying. The uC can be programmed to display on two digits while the IC's I selected can each display on one digit. The uC would still require a transistor array of some sort to interface to a larger display due to the voltage and current requirements.

    No problem. So no to the auto-repeat buttons and flashing. Yes to the remote operation and using a larger display.

    I used this. I couldn't find a product on Wal-mart's site, but I have seen them in Wal-mart, Target, and even Crackle Barrel for $10 ($9.97 or so). My circuit includes a reset function, so if you want up, down, and reset, then you want a cheap RC toy with four functions - forward, reverse, right, and left. Just don't get the ones that only go forward and spin in circle backwards - not enough signals. I don't see a problem with a 25' range, but to be honest, I didn't do much in the way of range testing. To be safe, play with car first to make sure it gets the range you need. If not, return it for a larger car with presumably more range.

    To connect to the circuit, you'll take apart the car and locate the circuit board (receiver). From there, you'll locate the wires going to the drive and steering motors - cut or desolder those from the motors. These will go to Q2-Q4. When the forward button or knob on the remote is engaged, one of the two wires that went to the drive motor will be +, the other - (GND). When the reverse button is pressed, the polarity will be reversed. The inputs to the circuit are active high, so the circuit will only respond to the wire that is +. I'll need to know the battery voltage of the car when you get one; this will impact the circuit used to power the receiver in place of the batteries.

    Oh, that reminds me, if you aren't already aware, note the display will have to be plugged into a wall. You can use a cheap wall wart. The display would otherwise eat batteries regularly. The remote can be battery-powered. You can also make your own enclosure and use your own switches in place of the car remote if you choose to give it a more professional look.

    You can use pre-made boards like this or you can avoid soldering and go with a wire wrapped circuit. The one I linked would require multiple boards, but there are bigger boards available.

    I'll work on modifying the schematic as time allows.
  6. izon

    Thread Starter Active Member

    Mar 17, 2013
    OK !! quickly responding to say thanks again for all the tips... they are so helpful and espcially appreciate the tip about the "filter". Yes that photo attachment of the unit
    built into a box looks exactly like I had in mind. There really doesn't need to be even a descriptive word as only staff will need to know what it is about so I could make it without that. I also do a bit of woodworking (very little and not very professional) so
    I'm sure I could construct an enclosure out of wood.
    Will follow up with more later. Thanks for now.
  7. elec_mech

    Senior Member

    Nov 12, 2008
    Here is a revised schematic and BOM. Consider this a beta schematic - I suspect some things will change as you get more into it. I referenced extremely cheap (both in price and quality) LEDs. If money isn't too tight, you can go with some much better and brighter LEDs from Digikey or Mouser.

    Are you sure about the 12" digit height? My fear is you'll need a lot more LEDs to "buff up" the segments so they can be seen. Instead of having one row of LEDs per segment, you'll likely need 3. This will add to the complexity, cost, and time to make an enclosure, but nothing unreasonable.

    The first picture I posted with the filter is a ~9" digit height on a 12" x 12" PVC board. Would that height work? The schematic is for something like that. If you decide on 12", I'll post a drawing of what I'm thinking of. It's important to know this up front because it will change the schematic some and the total parts count - I just don't want you to start ordering any parts until the design is locked down, otherwise you'll be paying extra for shipping multiple times.
  8. izon

    Thread Starter Active Member

    Mar 17, 2013
    Thanks! I have several things going on here so may not be able to post back as quickly as I would like so appreciate your hanging in and helping out so much.
    On this last post, aren't both those attachments the same circuit? I thought one was going to be a picture but both were schematics.

    Regarding size... that earlier photo you sent of a finished product in a wooden frame... was the overall size of the box 12 x 12" so that the number portion was
    about 9" with the text above taking up about 3" ? Just trying to get a clear idea
    in mind of the number size in proportion to the box. Also, I assume that same photo
    shows the LEDs not lighted (since I don't see a power cord leading from it).

    I wonder if we eliminate the text heading on this 12 x 12" unit, if we might get by making the numbers about 10" x 10" without doubling or tripling the LEDs.
    Then I would definitely use better LEDs (haven't checked price yet) that may be
    brighter and maybe larger? Again haven't checked size and brightness availability and pricing. Could you please suggest from either DigiKey or Mouser, an LED size and
    brightness to consider?

    Again, the numbers will probably be fine with 10" size on a 12" plastic and centering them top to bottom, left to right. Oh, back on that earlier post showing the LEDs on
    a plastic (PVC) panel and the filter to the right.... at first I thought the filter was just an example of LEDs assembled on some transparent material because the reflections of whatever is in the room made me think I was viewing through the material... so makes good sense once you explained it. If we went with green LEDs, do you pick the
    same color for the filter or is that just some uncolored opaque material?

    So.... that's it for the moment... did a minimal look at Radio Shack circuit boards... I think you were referring to the ones that have copper pads around each hole or where pads include about 3 holes allowing for joining connections without always using jumpers. Local store had only a couple of samples. Suppose a guy might need about 4 of those and somehow "connect" them together to build the complete circuitry. Have you built on these yourself at some time?
    Would suppose one should use sockets for the ICs so as not to be as likely to damage or in case of error wiring, not as likely to mess up the IC leads.

    Thanks again... if possible, would you maybe have a "ballpark" figure on what this might add up to in costs with better LEDs of the single row configuration.... not counting the RC car or the "box"... but with the plastic and filter???

    Best regards..
  9. elec_mech

    Senior Member

    Nov 12, 2008
    Sorry, I meant to clarify. Many here like schematics posted in .png for quick review. I attached both a .png and PDF so you could easily print off the circuit. The size of the PDF is 11" x 17".

    Honestly, I can't quite recall. The picture of the gray PVC and red filter is on a 12" x 12" board. The Now Serving was smaller I believe. I'd guess the digit size was closer to 6". Overall maybe 10" by 10"? Sorry, it was ten years ago (wow).

    I'll create a formal BOM with part numbers and prices once we've nailed the size down. Cheap LEDs were like $2 for 100 (you'll need about that), the least expensive good LEDs with more output were like $8 I think in a quantity of 100. This doesn't factor in shipping, so the difference between the two goes down more because you'd pay extra shipping to get the cheap ones since all your other parts will come from Digikey or similar.

    The two digits are both assembled on the same piece of gray PVC. I simply placed a filter in front of the right one so you can get a feel for the difference a filter makes. You always match the filter color to the color you want to show through, otherwise it could get blocked. I placed a red filter over a blue display the other day and the display disappeared. So for your project, you'll want a green filter. The filter and PVC will be about $5 each if you buy two of each. For some reason, Tap Plastics will charge $10 whether you buy one or two, so I just play with the quantities until I get the most bang for my buck. Shipping is extra, but it isn't too bad.

    I've built several. Given the number of IC's, I'd suggest a strip board. This has long copper traces going across the bottom of the board. You just remove the portions of traces you need with a knife or Dremel. I'll look for one when I do the BOM.

    Never a bad idea. I'll include those in the BOM as well.

    Okay, let's try to nail down the display. Take a look at the attachments. Both are 10" high digits - one uses 5 LEDs per segment, the other uses 6. These can be printed on (U.S.) standard 8.5 x 11" paper and are to scale. I suggest printing them and taping them to the wall you plan to put this on. Then stand back from the farthest point you expect someone to see this from and decide if a) 10" is big enough, b) a single row of LEDs is viewable, and c) whether you prefer 5 or 6 LEDs per segment.

    Once that is locked down, we can proceed.
  10. izon

    Thread Starter Active Member

    Mar 17, 2013
    Great suggestions and details appreciated! Yes, the 10" size will work. Maybe this is going a bit extreme but I was wondering about going with 6 LEDs per segment and in a double row... Would the LEDs just be paralleled and would that change the drivers needed with a greater current draw?

    With not having an identical example to see "in person", it is still a bit hard to know how visible this will be from the greater distances. Your two templates were a great idea. Regarding them, did you have to use a drawing program and individually place those dots? So sorry for that tedious job you went through... then in the same breath I'm wondering if you had an easier way, could a similar template be made for a dual row version. Or... if I made this, how is the center row handled... just shift the
    existing up slightly and run the second row slightly down from center?

    Sorry to add all that to the consideration and BOM... I guess the total
    cost difference with the above option will also help determine whether
    or not to try the 6 LED version doubled or not.... to add to the mix, maybe
    a 5 LED doubled would be a bit more practical and a compromise.

    Your thoughts are much valued on all of this... BTW.. did you have any photos of the backside of the panel to see how your wiring was routed..suppose you just made a "buss" wire to join the common lines of rows
    of LEDs for part of the layout.

    Thanks again...
  11. elec_mech

    Senior Member

    Nov 12, 2008
    The six LEDs (vs. five) will require more voltage to drive, but nothing difficult. Two rows will double the current draw, but nothing the driver IC's can't handle. Wouldn't be a bad idea to create some air holes in the box to allow air cooling though.

    Then let's play with what I've already made. What is the maximum realistic distance you need the display to be viewable from straight on? What's the max distance at the maximum angle the display needs to be viewed from (if possible to find out)? I assume this is in an office environment with fluorscent lighting and about an eight-foot or so ceiling? If not, please describe the lighting and ceiling height. I can put my display into a cardboard box, hang it and take video or pictures at the distances you need and you can better "see" for yourself if it will be sufficient.

    I use Microsoft Visio, not real difficult. I'll play with some ideas and post them.

    The only difference is the cost of the additional LEDs. Given the same overall size of the digit and thus box, that is the only real increase. Basic green LEDs were about $8 for a hundred, so for two rows, it'll be $16ish. If that is okay for your budget, then no problems otherwise.

    I looked, but I don't have any photos handy at the moment. I just pushed the LED through the hole, then bent the two leads at 90° opposite one another. In this way, I was able to easily solder one LED lead to another without adding additional material. The LEDs are wired in series, so one end of the strand goes to the driver IC and the other end gets joined to the rest and connected to either power or GND depending on whether the display is common cathode (CC) or common anode (CA).
  12. elec_mech

    Senior Member

    Nov 12, 2008
    Okay, after a lot of staring, contemplating, and playing with different setups, I believe I have a couple of viable dual row candidates. Look at the attached and let me know what you think.

    If you decide on the 12 LED option, we'd put two rows of six LEDs in series. There is a ~1V drop across the driver IC, and going with a rough standard of a 2V forward voltage rating per LED, 2 x 6 + 1 = 13V. This would allow some play and we could select a 15VDC wallwart. The 14 LED option would require a 18VDC wallwart. Probably not a big difference in price though. To be safe, we'll probably add a 12V voltage regulator to the circuit so we don't exceed the IC's maximum voltage input level, typically 15VDC for CMOS.
  13. izon

    Thread Starter Active Member

    Mar 17, 2013
    Excellent ! Still waiting for a response from my daughter's office but wanted to try and send 3 photos she took on her phone of in the office.
    They may be too tiny to view or I maybe haven't done this correctly for you to see them.
    Anyway if you look very carefully to the center area where a corner wall
    appears, there is a small board where the number is now posted. The first two photos show it fairly well but the third is very far away and a sharp angle so that would be the most difficult spot to view from.. this project will help that immensely and they may be able to "slant" the display somewhat to favor those poor folks far away at the sharp angle.

    Well here we go...if you get the photos, great but otherwise I've messed it up here on my end. Had one more close up photo but cant find it right now. Will get back to you in a day or so.... thanks again.
  14. izon

    Thread Starter Active Member

    Mar 17, 2013
    Well the decision is to go with the 12 LED per segment (10" high). Looking at your template, maybe you will be giving me this along the way but I might like to know where the division should come between each segment. Just a pencil line drawn between the segments on the template will be a good way to illustrate this I suppose.

    Sooo if you can suggest the size and source of the LEDs and the "drill" size, I could plan on getting the right drill bit. If the hole size is going to be metric... guess I may have to order that since I don't have anything in metric.

    Anxious now to get the materials lined up and ordered once you have time to specify and suggest.... I have dealt with both DigiKey (here in Minnesota where I live) and Mouser so that will be easy. The source of the "plastics" will be whatever you suggest .... preferably both pieces from the same place for shipping savings.

    I have to go RC car shopping and make some plans on probably building the "box". Figured on routing a couple of "slots" (spaced by the height of the LEDs) into the 4 side boards so that I can slide in the LED panel and slide in the filter panel in front of it. Could make the box as shallow as possible but dictated by the height of the parts on the PC board and it's mounting method.

    I picked up one of these boards at a Radio Shack but don't know if it will work out or be big enough.

    I will just wait for your suggestions at this point on how to proceed.
    Thanks !
  15. datacreed

    New Member

    Mar 25, 2013
    Aren't those commercially available? I'm new here too and find as my life gets busier with work and family, sometimes the best solution is to find used items like this on CraigsList or Ebay. A four-year old tot can drain my free time to design, etch, and solder circuit boards faster than any thing else. :)
  16. elec_mech

    Senior Member

    Nov 12, 2008
    Okay, as requested, I've attached a picture of the back of the red display showing how I wired it. I basically bent the leads on the LEDs together and soldered them. Be sure you test and orient them properly before soldering though.

    I also went ahead and tested my cheap, diffused green LEDs to get the best and brightest and made a 12-LED segment display with cardboard with digit height of 10" - followed the diagram I made and posted last time. It ain't pretty, but it functions.

    Looking at the pictures you posted, the ceiling tiles appear to be standard U.S. 2' x 4' panels, so I estimated the farthest distance back was about 36' and the farthest distance to the side was close to 50'. Using some trig, longest distance came out to ~61'. Worst-case viewing angle is about 65 degrees from center if looking at the display head-on.

    I then threw the display into a box and took a some pictures at work at a distance of ~75' head on. I could see it clearly. It was hard setting the camera zoom to take the picture with the same clarity as I could "see" it, but I think I got close. I don't know if I could count the LEDs, but I could clearly see the digit and that it was made up of individual LEDs.

    I tried turning the display at a 60 degree angle, but the display was so far in the box that it wasn't feasible. I still think it these LEDs are the best bet though. I tried much brighter, non-diffused LEDs and while brighter, the viewing angle was so tight that if you weren't facing them just about head on, you couldn't see they were on. Of course, you can find and buy all kinds, but the simple diffused ones should still work quite well at an angle and won't cost much (compared to the others).

    I only had a 0.01" thick light green filter, but I took a picture with and without it. Can't say I can tell a big difference, but putting it in a proper case and darker/thicker filter material should make it stand out more.

    You may need to add a small visor over the top of the display if it will be directly under any lights.

    Unfortunately, the layout just isn't right. You'll be making a lot of extra jumper wires to account for the short traces. Let me see if I can find you a stripboard on Digikey, this will save you a lot of time.

    I'd strongly suggest prototyping this on a breadboard just to work out any kinks before you solder a circuit. One lesson I should already know but learned the hard way again this weekend was the LEDs I used were rated for 2.4V, not 2.0V. This meant I had to increase the power supply to at least 15VDC. Because of losses in the driver IC, you'll probably need an 18VDC supply to be safe.

    Okay, so if the attached pictures are good, we'll go with the 12 LED per segment, 10" digit height design using green LEDs. I'll modify the layout so there are crosshairs over the LEDs. You can then simply print out the layout and tape it to your board, mark the holes with a scribe, remove paper and begin drilling. Do you have access to a printer/copier that can print on 11" x 17" sheets? If so, I can put both digits on the same paper and you don't have to worry about aligning the two digits.

    I'll have to double-check the drill size when I get home. If you have a 1 to 60 drill set, that should be fine.

    I'll start putting together a formal BOM with Digikey part numbers and prices.

    Ah, but what's the fun in that? Besides, you can choose your color, brightness and add whatever features you want now or later. Plus think of all the glory and kudos the office will have for izon. Okay, probably not, but it could happen. I understand what you're saying though. I have a three-year old myself and finding time is certainly a challange. Thankfully he likes playing in the shop which is a double-edged sword. :eek: Welcome to AAC datacreed.
  17. elec_mech

    Senior Member

    Nov 12, 2008
    Okay, here is a drilling template for two digits. This will need to be printed off on a 11" x 17" sheet of paper. I'd suggest printing it then cutting off the sides a bit and placing it over a 12" x 13.75" wide marked off area or draw a rectangle on a large piece of cardboard. You need to figure out how much space you want around the digits. I'm thinking 12" high by 13.75" wide as this should give you about half an inch from the from the digits and another half an inch to go into the slots and/or cover with molding or similiar. Best to "see" this before ordering a piece of plastic too small. You may decide on different dimensions which is fine.
  18. izon

    Thread Starter Active Member

    Mar 17, 2013
    Awesome photos ! Looks really great and whatever LEDs you think are justified is fine with me. You will have to clarify later which ones will be used and what power supply will be necessary to match things up.

    I guess I could breadboard the main circuitry but the LEDs are going to have to be put into the drilled board and wired together in order to see
    them work which will be a go or no-go situation once it is constructed.

    Your recommendation on the filter will be fine on whatever you feel is best. So.... the drill hole size is stated in US measurement, not metric?

    I will try to go to the library and see if they can allow a print out of that size as I have no way of doing it myself. I guess just one digit on a standard 8.5 x 11 page and then duplicated and laid side by side and taped on with the appropriate spacing should not be too difficult as an option. Maybe for that you would have to create a new one based on any
    changes we've made from the first 12 LED version you sent earlier. ... or
    would that one also suffice?

    So you will suggest a PC board to assemble this onto? Do you have any
    software that helps lay out the component placement on whatever board you are suggesting? I saw something about some free software that allows a person to do that but I'm not familiar with it or how to use it.

    Would like to get parts ordered today if possible as I would have some time this weekend to get started but will be a little iffy on getting an order in time if it comes from a distance... oh well...

    Thanks and kudo's again for the awesome work on setting up a working example and the photos submitted... this should be a real winner if all works out !
  19. elec_mech

    Senior Member

    Nov 12, 2008
    Order parts today? Hmm, I'll try, but I can't promise. Everything will come from Digikey though and they accept orders up until 8pm last I recall, so shouldn't be a problem to get everything by the weekend.

    I've created a single-digit template with lines that will allow you to cut the edges and match up two digits with the same distance apart as in the last posting.

    Forgot to check the drill size at home, but it will be a wire size drill, probably number 9 or 8. If you don't have those, Digikey might.

    I'll try to do a stripboard layout if time allows.
  20. elec_mech

    Senior Member

    Nov 12, 2008
    You can order the plastic now if you wish. It's out of the West Coast, so ordering now would be ideal.

    Go here and select 1/8" thick transparent dark green acrylic.

    Go here and select 1/8" dark gray PVC or here and select 1/8" black ABS. The black will better contrast, but the surface is textured, so up to you. Both should be easy to drill.

    Sizes will have to be figured out by you. I'd say 12" x 13.75" for each, but you should check this and see if it will work for what you have in mind factoring in the box, covering, etc.

    Now, if you happen to have a local plastic shop, you can get this there as well. I just haven't had much luck in my area.