# Help modify a MOD 13 counter

#### northpark

Joined Oct 27, 2020
14
The counter is designed to count through a maximum of 16 states but has have altered it to become a MOD-13 (counter which will count through only 13 states). Discuss how the counter able to do this in real time and what considerations must you take into account to make it count to some other number that is less than 15 prior to resetting. Can somebody help me with this question plz.

#### Delta prime

Joined Nov 15, 2019
843
Hello there.
really close to homework so I have to ask is this homework? I'll give you a hint say no

#### jpanhalt

Joined Jan 18, 2008
11,088
Well, it's now in the homework section. The TS needs to: 1) Show the circuit; and 2) Show his best attempt at answering the question.

#### northpark

Joined Oct 27, 2020
14
Well, it's now in the homework section. The TS needs to: 1) Show the circuit; and 2) Show his best attempt at answering the question.
I have it circuit built and everything works fine.. and i have to do a conclusion ... if you can help me put that wording into layman's term, I think that's all I would need.

#### dl324

Joined Mar 30, 2015
12,794
Welcome to AAC!
The counter is designed to count through a maximum of 16 states but has have altered it to become a MOD-13 (counter which will count through only 13 states). Discuss how the counter able to do this in real time and what considerations must you take into account to make it count to some other number that is less than 15 prior to resetting.
Post the entire text of the problem and schematics for the counters so we can better understand what you're trying to describe in words. When discussing circuits, we prefer schematics.

#### Papabravo

Joined Feb 24, 2006
15,772
Show us the schematic for the MOD-13 counter so we can help you answer the question. The verbal description covers a large universe of possible solutions and we cannot guide you to the solution without more information. OK for those in the cheap seats: no schematic no solution and no exceptions. Can you comply with this request?

#### northpark

Joined Oct 27, 2020
14
For the conclusion, consider the schematic that you've developed. The counter is designed to count through a maximum of 16 states but has have altered it to become a MOD-13 (counter which will count through only 13 states). Discuss how the counter able to do this in real time and what considerations must you take into account to make it count to some other number that is less than 15 prior to resetting.

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#### dl324

Joined Mar 30, 2015
12,794
consider the schematic that you've developed
Which counter is this? The original or modified? You have a short between Q0, Q2, and Q3.

#### Papabravo

Joined Feb 24, 2006
15,772
I'm going to guess that since you have tied the JK inputs to logic 1, that it is equivalent to having each JK flip-flop toggle on the clock edge.
The Q0 flip-flop has the clock input tiesd to logic 1. This means it will never toggle. If Q0 won't toggle, then neither will Q1. Then neither will the rest of the flip-flops toggle.

The JK flip-flop is incredibly versatile and generally when you make a counter, you want to make a synchronous counter which requires all the flip-flops to get their clock input from the same source.
I don't think your design has even a small chance of working. You need to go back to the drawing board.
You are also using the asynchronous clear incorrectly. As soon as the 7410 gate detect the terminal condition the counter is RESET. Oh...wait the counter can't count so it will never get there.

#### Papabravo

Joined Feb 24, 2006
15,772
Side Note:
The JK flip-flop can do four different things:
1. Set the Q output to a logic "1"
2. Set the Q output to a logic "0"
3. Leave the Q output unchanged, sometime we call the "holding the present state".
4. Toggle the Q output. A logic "1" becomes a logic "0" and vice versa,
Each of these four actions happens to each of the four flip-flops on one of the clock edges. The selected clock edge depends on the JK flip-flop part part-number.
The asynchronous Set and clear should not be used in this application. They are not needed, in fact using them in a counter will in most cases upset the apple cart.

#### northpark

Joined Oct 27, 2020
14
Which counter is this? The original or modified? You have a short between Q0, Q2, and Q3.
mod 13

#### northpark

Joined Oct 27, 2020
14

#### dl324

Joined Mar 30, 2015
12,794
Okay. It will work if you remove the shorts on the three outputs. What problem do you think decoding a reset count could cause?

#### northpark

Joined Oct 27, 2020
14
Okay. It will work if you remove the shorts on the three outputs. What problem do you think decoding a reset count could cause?
THINK I GOT IT

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#### northpark

Joined Oct 27, 2020
14

#### dl324

Joined Mar 30, 2015
12,794
THINK I GOT IT
Does your instructor grade on neatness? You have a number of unnecessary wire jogs and misaligned connections. You have 4 flip flops with essentially identical configurations for J, K, clock, and set; yet you drew them with 4 different variations.

#### jpanhalt

Joined Jan 18, 2008
11,088

#### northpark

Joined Oct 27, 2020
14
Does your instructor grade on neatness? You have a number of unnecessary wire jogs and misaligned connections. You have 4 flip flops with essentially identical configurations for J, K, clock, and set; yet you drew them with 4 different variations.

for the counter to be able to this this in real time, it had to me modified from a mod 16 counter to mod 13 counter and with the NAND gate set at 1101 to reset after 13 clock pulse...

#### dl324

Joined Mar 30, 2015
12,794
for the counter to be able to this this in real time, it had to me modified from a mod 16 counter to mod 13 counter and with the NAND gate set at 1101 to reset after 13 clock pulse...