counter circuit using up/down buttons driving led displays. - Page 1
Forum section: electronics / projects

author: geobee
author_rank: Contributor
timestamp: September 19, 2025, 07:38:06 am
content: Hi all, have had a request to try and build up a manual lap counter for a speedway club. The closest thing I can find is this board, but it has the limitation of counting up only, and not down. Maybe there could be a modification, or additional circuit added to solve the issue. Also, I need to replace the displays, instead drive two eight channel relay modules that will trigger two digit displays that are made up using LED strips, due to the larger displays required for distant vision. I know this is possible, as I have been given a unit to be repaired, but it is a ''rats nest'' of wiring etc, and not color coded etc. It was using an Arduino mega board as the brain, which has failed, causing me to want to start from scratch with it, and hoping to simplify it to boot. Any ideas would be great. Cheers.

author: Ian.M
author_rank: Super Contributor
timestamp: September 19, 2025, 11:28:58 am
content: The CD4553B is a three digit BCD counter with multiplexed output. Counters with multiplexed outputs are vanishingly rare nowadays as they were superseded by cheap microcontrollers. There is no three digit BCD up/down counter IC with multiplexed outputs*, and to build one from individual BCD up/down counters would take at least six ICs. If you ignore the multiplexed output, then 3x CD4029 counters and 3x CD4511B display drivers would get you there, but would involve rewiring the display to have a CD4511B per digit.The simplest solution *IS* the Arduino Mega - if you can code. If not, get someone who can to code it for you!Edit: However, Gyro's found you a four digit one.

author: SteveThackery
author_rank: Super Contributor
timestamp: September 19, 2025, 02:00:47 pm
content: I've got to agree - if you are a relative newbie, an Arduino would be ideal.The good thing with doing the job in software is that you could add additional features that might be requested in the future.

author: Gyro
author_rank: Super Contributor
timestamp: September 19, 2025, 07:17:46 pm
content: The ICM7217 is still in production after all these years (AD/Maxim now, originally Intersil), 4 digit up/down counter with multiplexed direct LED display drive.Not the cheapest solution compared to an Arduino but no programming required and plenty of hardware configuration flexibility. Might be worth a look.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: September 19, 2025, 07:42:04 pm
content: Quote from: geobee on September 19, 2025, 07:38:06 amSlave segment displays means multiplex drive outputs are best avoided.It sounds like the original wired each segment to a remote display?Usually you would avoid all that soldering and cables, but if that is already done, can you repair the Ardunio ?The code for 2-3 digits of 7 segment up/dn non-mux is only a couple of pages max.Did the existing unit give a long service life before it failed ?How does it handle up/dn? Two buttons or a rotary encoder?

author: geobee
author_rank: Contributor
timestamp: September 19, 2025, 10:29:38 pm
content: Hi there, thanks to all the replies. It had been operating for a few years, using just up down momentary buttons. The Arduino board had fried for some reason, and as I am a repairer of consumer electronics, do not see these type of builds very often. Repairing it as it was is not an option as all the wiring solder connections were covered with silicon, and all grey in color, just luck that it lasted as long as it did. Just like to simplify it so that it doesn't become a return customer on my bench.