Doing a bit or research, I believe the LED display is (or is similar) to an obsolete part, ELS-4005SURWA/S530-A3 , datasheet at https://media.digikey.com/pdf/Data%20Sheets/Everlight%20PDFs/ELS-4005SURWA_S530-A3.pdf
This part matches the size and pinout of your units. Each segment has 5 series LEDs with an If of 25mA and a Vf of 10-12V, thus no resistors required. -Bill- On Saturday, January 2, 2021 at 8:26:58 AM UTC-8 Bill Stanley wrote: > From a software point of view the Arduino should be able to generate the > signals. It is possible that a SPI interface will do a lot of the serial > conversion. > In terms of a library, once the serial format is known and if (big if) a > SPI port can be used, there is probably some library code that could be > used as a starting point. I'm sure someone can give a lot better > information. > There are a couple of things that I am not sure about based on your > photos... > > - You indicate that the LED displays are 12V. My guess is that the > linear regulator with an adjustment resistor for brightness actually drops > the voltage (13.6V) to the display The 4.6V is probably the logic Vcc. > - One thing I didn't see were current limit resistors. I wonder if > they are built into the display? > - I am also guessing that the displays are not multiplexed just based > on the fact that if they were multiplexed, the sequencing would probably > need to be handled by the missing "host" since I don't see anything on the > board to handle that. Also the fact that the 00.00 comes up and is not > extremely bright makes me think that current/brightness control is built > into the display and the segments/digits are not multiplexed. > > > I would be willing to take a look at a board and attempt a hardware > reverse engineer to generate a schematic for you. I could also take a stab > at generating a document on the driving of the unit. > > -Bill- > > > On Saturday, January 2, 2021 at 7:40:33 AM UTC-8 Jeffry P wrote: > >> Will an Arduino work? Is there alibrary that will produce these signals? >> >> On Thursday, December 31, 2020 at 4:19:22 PM UTC-6 Bill Stanley wrote: >> >>> Correct, these are a differential receiver to receive the serial (BCD) >>> information, 2x8 shift registers to convert to parallel BCD and 4 BCD to >>> seven segment LED drivers. >>> >>> With a bit of sleuthing, the schematic can be reverse engineered, >>> reverse engineer the serial format and build or use a COTS CPU like Pi to >>> display anything you wish. >>> The power supply connector also probably has the serial data (look for >>> wires going to the AM26LS32). Somewhere there will be a connection to >>> inject that serial stream. >>> >>> >>> -Bill- >>> >>> >>> On Thursday, December 31, 2020 at 1:30:17 PM UTC-8 bani wrote: >>> >>>> These are not standalone clock displays. They are driven by an external >>>> controller over serial. If the controller is not integrated into the >>>> PSU, >>>> then you are missing the external controller module. >>>> >>>> Personally I would just design a completely new clock using the LEDs. >>>> >>>> -Dan >>>> >>>> On Thu, 31 Dec 2020, Jeffry P wrote: >>>> >>>> > I purchased a clock display system from a USPS auction about 20 years >>>> ago >>>> > and recently rediscovered it in my storeroom. There are 20 displays >>>> and a >>>> > power supply. The displays were housed in a metal enclosure that has >>>> a >>>> > window cutout for the LEDs. The window had a piece of red colored >>>> film and >>>> > the LEDs were behind. When I plug the power supply in it will light >>>> all 0's >>>> > and a decimal point (as seen in photos), but will not start keeping >>>> time. >>>> > I'm willing to send one of these boards( at my expense) to someone >>>> who can >>>> > help me get the thing keeping time again. I've attached a few photos >>>> with >>>> > descriptions of chips that are on the board and voltages measured at >>>> the >>>> > power supply connector. >>>> > >>>> > Thank you, Jeffry >>>> > >>>> > >>>> > -- >>>> > You received this message because you are subscribed to the Google >>>> Groups "neonixie-l" group. >>>> > To unsubscribe from this group and stop receiving emails from it, >>>> send an email to [email protected]. >>>> > To view this discussion on the web, visit >>>> https://groups.google.com/d/msgid/neonixie-l/85636c40-6036-40b9-9426-24310206c979n%40googlegroups.com. >>>> >>>> >>>> > >>>> >>> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/a7a5029e-efae-416c-9eb9-730b9ab5b4aan%40googlegroups.com.
