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Electronics 7-segment LED Clock

Discussion in 'Modding' started by Explicit, 27 Sep 2004.

  1. Turbokeu

    Turbokeu Minimodder

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    And my actual VFD display collection...

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    All above are new or in perfect working condition.
    I'm now waiting on the delivery of 16 additionnal IV-11 tubes, and 14x IV-1 tubes (little tubes with a trema and and a round dot for the semicolons), and several single nixie- and VFD-tubes for my collection.

    If people overhere own one of more superfluous Nixie or VFD tubes (even defective), I'm trying to expand my collection and I'm prepared to pay for the tubes and/or the shipping costs.

    CD :)
     
  2. bigal

    bigal Fetch n Execute

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    this is getting insane... so many nixies so little time! You should start a buisness in them!
     
  3. salb203

    salb203 What's a Dremel?

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    Chris,
    You now acquired Led, VFD and Nixie tubes, your next step in collecting are RCA Numitron Tubes which as you probably know are incandescent 7 segment displays like the clock I built below. Each segment needs 5 volts to light up. You can see the rest of my clock at http://www.numitron.com

    Regards,
    Sal Brisindi

    [​IMG]
     
    Last edited: 22 Jul 2005
  4. Turbokeu

    Turbokeu Minimodder

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    Hi Sal,
    I already found your Numitron clock while searching for schematics.
    And yes, I'm thinking to acquire some Numitron tubes...:D

    Regards,
    Chris
     
  5. salb203

    salb203 What's a Dremel?

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    One you try a Numitron clock, there is no turning back... ;-).

    Regards,
    Sal
     
  6. Turbokeu

    Turbokeu Minimodder

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    In the meanwhile I modified the clock code to work with a binary coded clock/calendar routine with leap year detection/correction.
    Therefore it was easier to implement a time check between 11:59 and 03:01 to disable DCF update (to accomodate for DCF day, month, year and winter/summer time updates) when CET-1H or CET+1H timezone is selected.
    I also modified the display routines to be compatible with (LCD-compatible) VFD displays:
    [​IMG]
    The minus-sign before the hours is to check the actual timezone setting for debugging purposes.

    CD :)

    PS: I also found some RS232 "big" IEE 1x20 VFD displays (surnamed "The moose" by IEE).
    Digit size is 15x8mm, display is 350x60x40mm (13.8x2.36x1.57").... :naughty:
    (for comparison, the Noritake VFD display on the above picture has 3x5mm digits)
     
    Last edited: 31 Jul 2005
  7. Turbokeu

    Turbokeu Minimodder

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    IT'S ALIVE!!! :clap:

    I fiddled quite a bit with the schematics and the software (based on the above LCD/VFD version), but here is my little baby...: LED Clock version 1.0, with blue 9mm displays.

    On the left rear, the LED clock schematic (which isn't final), on the right rear a first version of the LED Clock main board PCB layout, in front the breadboard with the PIC 16F876 with 4543 BCD-to-7-segment-decoder, 74HCT238 multiplexer, and ULN2803 and TD62783A drivers.
    [​IMG]
    Everything is functional (DCF77 decoding, time/date display, CET, CET-1h, CET+1h time zone), except for the LDR A/D conversion and the PWM display brightness control (ready but disabled in software).

    I developped a little PCB for the 9mm LC-Led blue 7-segment displays (actually two, the first was completely wrong, as do the LC-Led datasheets...).:duh:

    [​IMG]

    A little close-up of the displays:
    [​IMG]

    On the right the four status-LEDs:
    Blue: DCF77 Beat
    Red: DCF77-Error
    Green: DCF77-Frame OK
    Yellow: Free-running LED (when CET-1 or CET+1h, between 22:59 and 03:01H).
    [​IMG]

    I already discovered a little bug:
    The 250Hz multiplex frequency of the displays is too low (a little visible flickering), has to be increased to 1000Hz in software. :sigh:

    CD :D

    PS: All my thanks to Richard (a really great guy on this forum!) for his priceless help during testing and debugging...
     
  8. bixie_62

    bixie_62 Minimodder

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    flippin' 'eck!
    when you gna have the pcb's ready for purchase??!?!?!?!
    that dcf77 thing sounds interesting,will this sync to greenwich mean time or will it just be to the one at the base?
    would schematics be postable?!
    thanx.
     
    Last edited: 15 Aug 2005
  9. Turbokeu

    Turbokeu Minimodder

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    The DCF77 transmitter near Frankfurt transmits CET time (GMT+1H), but my software allows for CET-1 or CET+1 timezone setting through jumpers on power up.
    As my routines also include a standalone 24H-clock/calendar (if DCF77 should be unavailable momentarily), I disabled DCF synchronizing (leaving the clock running standalone) for the CET-1 and CET+1 timezones between 22:59 and 03:01H (as I have to add or substract 1H from the CET time/date and take care of day/month/year/leap year changes).
    Actually busy checking everything (a few little bugs remain), and the automatic PWM brightness control through a LDR has to tested out.

    Once done I can finalize the schematics and clock PCB layout.

    The clock PCB will be universal: the display segment resistors are on the display board, an external 9-24V voltage (depending of the used displays) is used to drive the display anodes, the 5V logic voltage is produced on the board itself, ULN2803/TD62783A drivers are used for segment/anode driving, therefor ANY size or color of common anode displays can be used.

    In the next days I will also test a RF 433MHz keyfob transmitter and a 433MHz receiver/UM3758A decoder to replace the actual pushbutton to switch between time and date display.

    I will surely post the final schematics and PCB layouts (and on my webpage too).

    CD :)
     
  10. Turbokeu

    Turbokeu Minimodder

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    This has nothing to do with a blue LED Clock (except it's blue too) but these are not bad:

    Ladies and Gentlemen, I'm proud to present you "The Moose": :clap:
    (I put a pen and a MS mouse next for comparison)

    [​IMG]

    [​IMG]

    VFD display (model 03601-16-020) from IEE (Industrial Electronic Engineers), nickname "The Moose".
    1x20 characters, 5x7 dot matrix, 15x9mm digit size, RS-232 and parallel interface, 5V/900mA power supply.
    New, in original box.
    Dimensions: window 30.2x3.8cm, external 39.1x6.3cm, height 4.4cm.
    Bought them fairly cheap (30 Euro/piece without shipping), I can obtain four more of them.

    I think I will make clocks of them too... :D

    CD :)
     
    Last edited: 18 Aug 2005
  11. Turbokeu

    Turbokeu Minimodder

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    Okay, this is the schematic of the LED Clock as used on the picture of the breadboard circuit above:

    (Click image for PDF format)
    [​IMG]

    The mentionned +24V is for the 2.3"-4" display version, I actually apply +9V for the 0.36" displays together with 150 Ohm segment resistors. Also the indicated serial resistors for the LEDs may vary depending on the used voltage and type of LEDs.
    S2-S3 are jumpers for Timezone setting (+/-1H), S1 is the Time/Date pushbutton, S4 allows for automatic Time/Date switching every few secs.
    The last two can be remotely controlled by a Velleman RF433MHz keyfob and a RX433 receiver + UM3758A decoders on input 1 & 2.

    The resistors around the LDR resistor are not final, I have still to test out some correct values.

    The fickering issue on the display has been resolved.
    The display was updated every 4msec (250Hz/digit), giving a refresh frequency for the six displays of 41.3Hz, way too low.
    Now the displays are updated every 2msec (500Hz/digit) giving a refresh frequency of 83.2Hz, no more flickering at all.

    A few little bugs remain in the status LEDs management but I'm working on it.

    Finally some progress!

    Happy CD :D
     
    Last edited: 26 Dec 2006
  12. bixie_62

    bixie_62 Minimodder

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    any chance of a PCB diagram?!
    would you be willing to sell any of those 7 segment displays at all?
     
  13. Turbokeu

    Turbokeu Minimodder

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    Sorry, all displays are reserved for clocks for family and friends...
    If by chance (for you) somebody changes his mind, I'll let you know.

    First version of PCB layout is done, have to test out the values for the resistors around the LDR.
    Should be done in a few days, then I can publish the final PCB layout.

    CD :)
     
  14. jerb111

    jerb111 What's a Dremel?

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    could you please redirect me to the schematic for people living in america?

    also, the one posted above will work w/ the 4" LED Displays, correct?
     
  15. Turbokeu

    Turbokeu Minimodder

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    The schematic without DCF (but with DS1307 RTC chip) doesn't work yet (it exists but the software has yet to be adapted from the DCF77 version), I have first to finalize the DCF version...

    Please read my previous posts. Yes, the above schematic is specifically for 2.3 or 4" displays, but depending on the applied display voltage and segment resistors ANY size or colour of common anode displays can be used.

    It's just a matter of choosing the right display voltage (a couple of volts more than the segment voltage) and calculating the correct segment resistors.

    CD :)
     
  16. jerb111

    jerb111 What's a Dremel?

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    thanks for clarifying all that, looking good so far



    subscribed! :rock:
     
  17. Turbokeu

    Turbokeu Minimodder

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    I made a little video of the scrolling Time/Date switching.
    There's still a bug where the month and year display remain at 00 but I'm working on it.

    Scrolling.avi (4.2MB)

    CD :)

    Edit: The date bug has been resolved thanks to Richard of this forum!
    I can't imagine that I overlooked the error in the code several 100's of times... :wallbash:
     
    Last edited: 29 Aug 2005
  18. Turbokeu

    Turbokeu Minimodder

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    As the automatic LDR+PWM brightness control now works great, the status LEDs have a quite annoying (fixed) brightness that overwhelmes the brightness of the displays themselves in dark ambient light conditions (during the night it's almost like there's a police car with running flashlights in my kitchen due to the blinking blue DCF beat LED... :D )

    Here's the modified schematic :
    (Click image for PDF format)
    [​IMG]

    I used the last free driver section on the TD62783A to multiplex the status LED's power supply line together with the seconds digit and the PIC outputs to the LEDs are now switched through a NPN transistor.

    CD :)
     
    Last edited: 2 Sep 2005
  19. Turbokeu

    Turbokeu Minimodder

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    Succeeded to finish the development and etching of the 0.8" white, 1" blue, and 2.3" blue display boards...
    The 4" display board layout is finished too, now waiting for the 22.5 x 20" photosensitive Bungard PCB sheet that I ordered to etch it.

    The 0.8" white, 1" blue and 2.3" blue display board, on the left a (bugged) version of the LED-clock main board:
    [​IMG]

    Close-up of the 0.8 white and 1" blue display board (remark that the colon LEDs are missing, I'm still waiting for them to be delivered).
    [​IMG]

    Close-up of the 5mm Blue LEDs for the colons of the 2.3" board: I filed and sanded them to be at the same size as the DP's and at the same level as the digits.
    [​IMG]

    Close-up of the status LEDs on the 2.3" display board
    [​IMG]

    Previous boards together with a printout of the 4" display board
    [​IMG]

    With the 4" displays...
    [​IMG]

    Close-up of the LED-clock main PCB (I now have a new layout with a RF433 receiver/decoder and a SAE800-based hourly gong)
    [​IMG]

    I spray-painted the PCB's and most of the sides of the digits in black to hide the lighter colour.
    I hope I will have all the missing parts this weekends so that I can take some pictures of the display boards in action.

    CD :)
     
  20. Turbokeu

    Turbokeu Minimodder

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    I forgot...

    The segment and status LED serial resistors are (or will be) mounted onto the display board, therefore the clock PCB is 'universal', or independent of the used displays
    [​IMG]

    I had to make the 2.3" display in two parts (with the new ordered big PCB sheet, no more issues!). The Main LED-clock PCB will be attached to the display board through standoffs (this is the function of the four big visible solder pads on the solder side).
    This is how I soldered the two parts together:
    [​IMG]

    Overview of the copper side of the three boards:
    [​IMG]

    CD :)
     

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