Hi. Im trying to do this same project and am running into a bunch of issues - Im using all the same chips (74SL47 rather than 74LS247) and can get one digit to light up and count up. As I try to add the second digit all goes to hell. Im using MXA002 5" seven segment LED displays (they look amazing working) Im wondering if there are issues with the diagrams in this thread or if they indeed work completely as drawn. In my very very limited electronic knowledge I know there is an error with the vcc/gnd on the 14 (schmidtt trigger) - they appear to be backwards on the drawing. please advise as to where to go from here
Hey,
still someone here?
The drawing ist exactly what I need. So thank you for that!
I want to built an up down reset counter with 3 digits. So i´m taking the drawing of the "basic 3 decade up/down counter and combine it with the "two digits up down counter" by using its 74ls14 drawing. that should work, right? I also attached the combined drawing.
I have a question about the 5v Input and the 100n and 100u capacitor. are those two before all the other 5v inputs (on the chips and the 7seg display) or only before the 7seg display (because there the input are not marked red).
the 5v input (on the right hand side) on the 74LS247 isnt "saved" with an capacitor. is that right?
So I´ll find the 74LS192 chip. And connect the pins 3,4,5 as you said (see picture below).
Maybe you can also help me with the power-supply-thing which i´m not shure about.
I did different drawings (in blue so you know what i changed) on the drawing. Because I´m not shure how to connect the powersupply properly to the chips and to the 7seg Display. What do you think, picture (1) or (2) or none of those? does the CA sign on the displays mean Capacitor?
I am assuming you are referring to the circuit from post #64. You need to describe the fault more clearly. Is it just the units that is skipping or are the 10's and 100's skipping. Is it consistent. For example does it count 000, 001, 002, 005 or is it random. ? What kind of construction are you using and what kind of power supply are you using ?
hi eric,
i tried to build the two digit counter that you posted and it is randomly skipping count and sometimes i have to press the minus switch a couple of times to get a result, do you think a switch debouncer could fix this? if so can you recommend a circuit?