I tried to make a quiz game show circuit thingy.

Thread Starter

electronics123

Joined Feb 22, 2020
47
I tried to make a quiz game show circuit thingy, like the ones in Jeopardy, to have a game night with my family. My circuit doesn't work as there are 2 leds lighted up instead of 1. Other than adding a pull up to each d flip flop what else could i do? Also anyone know how to make it such that there is a certain amount of time before they cant answer anymore or like a certain sound for a wrong and correct answer.

WhatsApp Image 2020-07-19 at 5.10.03 PM.jpeg
Screenshot 2020-07-19 at 5.24.49 PM.png
 

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AlbertHall

Joined Jun 4, 2014
10,245
We have to give advice based on an inaccurate schematic. You should note that therfore the advice may be inaccurate!

You have logic inputs left floating. This is asking for trouble, especially with CMOS logic. They should be connected to VCC or 0V as appropriate for your circuit.
Are these TTL or CMOS chips?
 

Thread Starter

electronics123

Joined Feb 22, 2020
47
We have to give advice based on an inaccurate schematic. You should note that therfore the advice may be inaccurate!

You have logic inputs left floating. This is asking for trouble, especially with CMOS logic. They should be connected to VCC or 0V as appropriate for your circuit.
Are these TTL or CMOS chips?
oh ya the input is floating, these are CMOS chips
 

Thread Starter

electronics123

Joined Feb 22, 2020
47
We have to give advice based on an inaccurate schematic. You should note that therfore the advice may be inaccurate!

You have logic inputs left floating. This is asking for trouble, especially with CMOS logic. They should be connected to VCC or 0V as appropriate for your circuit.
Are these TTL or CMOS chips?
it isnt a inaccurate schematic, i was just too lazy to update it!
 

ericgibbs

Joined Jan 29, 2010
10,501
hi,
OK.
Switch Off the 5V power, wait about 5seconds, power up, what state are the LED's showing.?

BTW: add some decoupling to the5V rail say 47uF and 100nF.
E


Update:
When S4 is Open the Reset pins are floating!
 

Thread Starter

electronics123

Joined Feb 22, 2020
47
hi,
OK.
Switch Off the 5V power, wait about 5seconds, power up, what state are the LED's showing.?

BTW: add some decoupling to the5V rail say 47uF and 100nF.
E


Update:
When S4 is Open the Reset pins are floating!
add a another pull up to s4?!
gonna hv to try that another day, had to go to visit my parents :)
 

Thread Starter

electronics123

Joined Feb 22, 2020
47
hi,
R7 is not required, add a 4k7 to the Reset line as a pull up, so when S4 open the F/F are reset.
E
that should fix everything? Also do you know how to make it such that there is a certain amount of time before they cant answer anymore or like a certain sound for a wrong and correct answer.
 

bertus

Joined Apr 5, 2008
20,662
Hello,

@ericgibbs , As I see the IO1 is the 5 Volts from the supply.
See the right side at the supply.
The only thing that worries me is that all labels are as output.

@electronics123 , Wich chips are you actualy using?
That way we can see wich pins need to be grounded or out high.

Bertus
 
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