555 timer and counter

[dwuihf]

i am trying to construct 555 timer with 8 bits counter to reset after 180 seconds(3 minutes). and i want to see the waveform of time counting. i have done this circuit but it seems not working.can u help me to construct it again and i how to view the waveform.i am using multisim simulation software.thanks

[Talal91 · Accepted solution]

post the schematic of your circuit

[dwuihf]

hi,here is my circuits, one for egg timer and another is 555 timer with 8 bit counter.i need clear explanation how they work and is there any wrong connection in both circuits? 

[dwuihf]

hi,here is my circuits, one for egg timer and another is 555 timer with 8 bit counter.i need clear explanation how they work and is there any wrong connection in both circuits? 

the capacitor is 1 uf not nf.

[Tien_P]

Hi,

If you move the LEDs to the right of U5 around, many of them doesn't have a wire following it and this means these LEDs were not wired correctly.  I recommend that you use the 7 segment LED instead, it make reading the circuit much easier.  You can find the 7 segment by going to Place>>component, go the "Indicators" group,highlight the "Hex Display" family, there are many different component you can choose from and the one I picked was "DCD_HEx", it's not a real component that you can buy but in Multisim it easy to use.

I took your "Design 4" file, rearrange the components a little and only showed the first counter stage and your circuit is counting.

[dwuihf]

thanks for help.how can i can i display the square waveform for 4 bit and  8 bit counters? i need 16 binary square waveform for 4 bit counter and i want to modify 8 bit counter to count  from 0  to 180 seconds(00000000 to 10110101) 

[Tien_P]

To view the digital circuit waveform use the Logic Analyzer instrument, it should be on the "Instruments" toolbar on the right side of the Multisim screen, or you can select from the main menu Simulate>>Instruments>>Logic Analyzer.  The 16 pins on the side are for you input signal.

[dwuihf]

yes,but i am still not getting any waveform.i have connected logic analyzer.i need the waveform that generated by 8 bit counter.i have constructed the circuit.can u check it,if any thing wrong in connection? thanks

[dwuihf]

i want the counters count from 0000 0000 and reset at 10110101 ( from 0 to 180 seconds) and then clear back and recycle.

also i want to know the correct connection between 555 timer to the counters and NAND gates.

[Tien_P]

Hi,

Attached is a file to shows how to connect  the logic analyzer.

Your design have basically three stages, the first is the 555 timer which is main circuit clock.  To find out how to calculate what resistance and capacitance to use, you can refer to this page:

http://focus.ti.com/lit/ds/symlink/sn74ls163a.pdf

The output of the 555 timer goes to the first 74LS163, and it counts from 0000 to 1111.  The RCO pin outputs a high when the counter reaches 1111, use this as the input clock to the second 74LS163.  When both counters are at 1011 0101, you want to send a low to the clear pin on both counters.  Have a look at the datasheet for the 74LS163 for its operation.

74LS163 datasheet:

http://focus.ti.com/lit/ds/symlink/sn74ls163a.pdf