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Help timer circuit using 74190

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marco_26

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Hi, we are making a 3 minute timer circuit using 7 segment display and ic 7447 and 74190. The time starts to count but up to 99. How can we make it up to 59 then back to 00? Thanks!
 
Hi, we are making a 3 minute timer circuit using 7 segment display and ic 7447 and 74190. The time starts to count but up to 99. How can we make it up to 59 then back to 00? Thanks!

hi marco,
Please post the circuit that counts upto 99 and we can suggest how to modify it for 59 >>00
 
Hi.I have a same problem.i use 74190 and it goes to 99.how can i change it?59>>00
 

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    2013-10-06_211820.png
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you have to make a logic high when logic state of 2nd counter just changing to 6 and connect it to reset both counters, you may need to use few AND / NAND gates to get logic high for reset.
 
you have to make a logic high when logic state of 2nd counter just changing to 6 and connect it to reset both counters, you may need to use few AND / NAND gates to get logic high for reset.

thanks.I try that before i write the first post.i Use nand gate.when Q1 and Q2 turns to 1 (0110=6) Nand gate turns to 0 and left 7seg must turn to 0(if pl=0 then 7seg resets).But when number turns 3 to 4 nand gate recognize that both of the pins are 1 and resets the segment (1100--->0010)
 
thanks.I try that before i write the first post.i Use nand gate.when Q1 and Q2 turns to 1 (0110=6) Nand gate turns to 0 and left 7seg must turn to 0(if pl=0 then 7seg resets).But when number turns 3 to 4 nand gate recognize that both of the pins are 1 and resets the segment (1100--->0010)

What if you do it like this.
 

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    74190 59 sec counter.PNG
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thanks.I try that before i write the first post.i Use nand gate.when Q1 and Q2 turns to 1 (0110=6) Nand gate turns to 0 and left 7seg must turn to 0(if pl=0 then 7seg resets).But when number turns 3 to 4 nand gate recognize that both of the pins are 1 and resets the segment (1100--->0010)

you must consider all four digits to get reset out, say if ABCD= 0110 then the combination must be A^BCD^ , similar to what absf posted.
 
If the clock speed isnt in the order of mhz you can do that with a couple of diodes and a transistor.
 
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