hello guys... i really need some ideas or better yet a complete circuit for a 3 digit up down counter...
i've just finished a monostable config 555 for its clock? and its working. then problem starts here. i've tried some circuits in some threads here but none of them are working. simulation or the real thing.
details:
manual switch for up,down,and reset
should use 74LS192
74LS47
7 segment display
i really need help on this guys. the project is due next week.
hi,
You are showing manual up/dwn switches into the LS192.
The LS192 has two 'terminal count' outputs, the 'carry output' when the 192 passes thru its maximum up count, this is connected to the next LS192's 'up count' input.
The other output is the 'borrow output' when the LS192 is counting down and it passes thru its 'zero' count, this is connected to 'down count' input of the next LS192.
Connect the 'reset' switch to all the LS192 as you have already done on the 1st stage.
it's not working... there's still no display. we think that the problem is in the decoder part. the output in the 74LS192 is counting as we've seen in the oscilloscope. we can't figure it out.
we tried putting inverters at the output of the decoder(74LS47) and we had a display. 8. it just means all the outputs before the inverters in the decoder are low.
here's the circuit. im using multisim for my simulation.
it's not working... there's still no display. we think that the problem is in the decoder part. the output in the 74LS192 is counting as we've seen in the oscilloscope. we can't figure it out.
we tried putting inverters at the output of the decoder(74LS47) and we had a display. 8. it just means all the outputs before the inverters in the decoder are low.
here's the circuit. im using multisim for my simulation.
yes! we finally figured it out. we were just so stupid to see it. the voltage in the display is just high. the preset voltage drop in the multisim program is 1.66V.
we also got the other digits figured out, which came easy since you helped me. we were just laughing at ourselves after, since it was not hard at all. but the only problem is the starting count is not "000". it would either display "999" or "001". we're thinking of connecting it first in the reset? any suggestions?
as i've posted earlier, we specifically need to do it with the given IC, which is 74LS192. but thanks for the suggestion.
using ICM7217 would not help us, because we don't have money to buy one. i'm from the philippines, and i'm pretty hard up on my finances since i'm only a student. same goes for my teammates.