problem with IC 74ls192 counters.

Thread Starter

Ling Shao Huang

Joined Sep 22, 2017
7
Currently, i am doing electronics kits. However, the result is not coming with my expected results. The counters will start at 999 once battery is connected. Reset function is good condition which can reset the counters to 0. Come to the 'UP' and 'DOWN', the counters will immediately jump to number 6 instead of 1 then followed by 10. it is constantly for further button pressed as 16,20,26,30.... While, down counters will jump here and there , sometimes reduce 1, 2 , 4 or 7. I hope that some1 can help me since it is good when stimulating with proteus. The counters can increase1 by 1 and decrease 1 by 1.
the figure is shown below :
upload_2017-12-20_13-33-0.png
 

Sensacell

Joined Jun 19, 2012
3,432
I checked the online solution , i did the same thing to my circuit as i added ceramic capacitor parallel to my switch .
Not the best solution- when the switch closes, the capacitor is shorted, causing a very high spike of current that can damage the contacts, or cause additional glitches.
 

absf

Joined Dec 29, 2010
1,968
The counters will start at 999 once battery is connected.
In order to start with '999', you have to preset the inputs D0-D3 to binary '1001' and add a switch to 'PL" to logic o.

Like this

74192 counter.PNG
You cannot use just one resistor on the common pin of the 7 segment LED. Otherwise it would have different brightness when displaying 0-9. Imagine 2 segemnts on on digit '1' while 7 segments on on digit '8'.

Also use Template/Set Junction Dot/ to 30th so the connecting dots can be seen easily.

Allen
 

Thread Starter

Ling Shao Huang

Joined Sep 22, 2017
7
absf , i am sorry about my english . 1 of the problems is counter will start at '999' but i want start with counter '0'. Another problem is counters keep jumping.
 

absf

Joined Dec 29, 2010
1,968
My circuit is just an example. You dont need the button if you have the logic to reset the preset.
If you want it to start with "000" then set D0-D3 to '0000'

try search for power-on-reset circuits from the internet. It only needs a capacitor and a resistor.

Allen
 

Thread Starter

Ling Shao Huang

Joined Sep 22, 2017
7
thx. but the main problem is counters keep jumping . for counter up, it will jump to digit 6 and 0. For counter down, it will jump 9,7,5,3,1. i keep checking the input , when i press counter up, it really shows 6 which is Q1 and Q2 in 'ON' state.
 

absf

Joined Dec 29, 2010
1,968
What kind of switches are you using? Did you add debounce circuits as mentioned in post #2?

Try one of the debouncing circuits HERE.

Allen
 

Thread Starter

Ling Shao Huang

Joined Sep 22, 2017
7
i tried the debouncer circuit on my project already. However , it is still troublesome. i just realize that my Q0 will keep on . No matter how many times i press on 'UP' button , it wont clear off.
the counter still jump.
 
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