Hello all. I am relatively new to electronics as a hobby. I have been computer programmer and wanted to get into the electronics side of things.
For my first project I wanted to make a Binary Clock using 555 timers and 74LS290 Decade Counters. I have the 555 timer sending out a pulse with a period of as close to 1 second as I can muster (about 987 milliseconds), and I have the first counter and the second counter set up properly.
To give you a better idea of how I did it, I have the Q0 and Q4 (1001 or 9) pins of the first counter going through a 2-input AND gate and that pulse is used to trigger the second decade counter. This one works fine.
Now from the second decade counter to the third to count a minute, I have to use pins Q0 and Q2 (0101 or 5) through a 2-input AND gate so when the final pulse of the first decade timer changes the second to 0110 (or 6) the falling edge of the logic gate output will trigger the third decade timer. However...the problem is when second decade timer is going from 0011 to 0100 at one point (for a very brief instant) both Q0 and Q2 are true during the transition...so the third decade counter picks this up as a pulse, as does the reset pins of the second decade timer, so it resets ten seconds too early and the third decade timer increments ten seconds too early.
I am at a loss as to how to fix this issue...any suggestions? Thanks in advance =3.
For my first project I wanted to make a Binary Clock using 555 timers and 74LS290 Decade Counters. I have the 555 timer sending out a pulse with a period of as close to 1 second as I can muster (about 987 milliseconds), and I have the first counter and the second counter set up properly.
To give you a better idea of how I did it, I have the Q0 and Q4 (1001 or 9) pins of the first counter going through a 2-input AND gate and that pulse is used to trigger the second decade counter. This one works fine.
Now from the second decade counter to the third to count a minute, I have to use pins Q0 and Q2 (0101 or 5) through a 2-input AND gate so when the final pulse of the first decade timer changes the second to 0110 (or 6) the falling edge of the logic gate output will trigger the third decade timer. However...the problem is when second decade timer is going from 0011 to 0100 at one point (for a very brief instant) both Q0 and Q2 are true during the transition...so the third decade counter picks this up as a pulse, as does the reset pins of the second decade timer, so it resets ten seconds too early and the third decade timer increments ten seconds too early.
I am at a loss as to how to fix this issue...any suggestions? Thanks in advance =3.