What I need; a 3 digit up/down counter!

Discussion in 'General Electronics Chat' started by Bog Wog, Mar 27, 2015.

  1. Bog Wog

    Thread Starter New Member

    Mar 27, 2015
    This would be great.. but now that Iv signed up, the thread I was following suggest starting a new thread. I cant seem to find ANYWHERE Im allowed to!
    Iv been staying up late.. nightly.. to try to get an answer to this issue. Another night of getting NOWHERE. Im really getting impatient..
    Im many things.. Commercial electrician is my main work but I used to do electronics (when digital was young!).. Digital stuff, Im outdated with and haven't worked or played with it in long time. I have a need, however. A 3 digit, 7 segment counter that counts up and down.. ONLY, not just from "000" up and "999" down... this unit is to be a really compact counter/control for a "screwdriver" antenna for HF operations.
    The motor is a dc reversible (by switching the polarity), driving a long drive screw (all-thread).. pushing the center load coil in or out of the top of the tube. Position of the coil is based on the counts of the drive screw turns... achieved by a magnet on the drive screw passing over a magnetic switch (reed switch). (this unit is interchangeable with other units.. forget the stepper-motor ideas).
    The counter MUST be about to go from baseline ("000" generally).. to anywhere between "000" and "999".. and reverse.. go back up.. then up some more.. and back down.. WITHOUT LOOSING ITS "000" REFERENCE!
    Iv looked at many circuits, understand the basics.. but I don't know what chip is good for what.. and many configurations.
    Iv looked at using a 74LS47.. I have a potentially usable schetmatic for 2 digits and planned to expend to the 100's column as I can easily see the outputs that are specifically the decoder. What I don't have is WHAT chips are being used! They appear to be the 74LS47 above as all the pins appear to be identical (power, segment outputs, inputs, power, ground, and the BI/RBO & RBI appear to be like wired as well). Schematic only shows "4511" for chip ID. The Clock chips are labeled as "4510". Does this click with anyone; is it familiar???
  2. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
    Below are links to the requested datasheets:

    The counter (4510):

    And The decoder/Driver (4511):

    FWIW Owing to the complexity (i.e. specificity) of your application, a better solution may be implementation of control and display functions via uC even 'dinosaurs' (e.g. 16F84, 16F88, etc...) are 'overqualified' for such applications... :)

    Best regards
    Last edited: Mar 27, 2015
  3. AnalogKid

    Distinguished Member

    Aug 1, 2013
    There are many 4-digit counters on ebay for under $15 including shipping. It might be less effort to implement one of them rather than design one from scratch. If you do want to build one, the old school way is with three BDC counters, three decoder/drivers, and three displays. Or, Maxim and Intersil make single-chip counter parts. The 74C945 or 47 will do it all in one IC, but it is obsolete and difficult to find.

    Roderick Young likes this.