quiz came circuit/decade counter

[T5]

Hi there!

i have a quiz game circuit and a decade counter ciruit. i would like to combine the two together so that the counter ciruit is connected to switch 1 only on the quiz circiut. the circuits are at the following link:

the top circuit shows the quiz and the bottom is the counter.

can anyone combine the two together as i have tried but to no avail.

 

[MMAshwin]

Hi,

Tried accessing that URL but no joy. Maybe the servers down.
If you want email me the circuits & I'll have a look.
Use: tps72v4@hotmail.com
Any help ?, yes no let me know.

Regards

 

[T5]

Hi

the link does work, i think it may be becuase of a bad internet connection. please try it again if not i'll mail it to ya!

laterz...

 

[MMAshwin]

Hello again,

Yep that link is working now.

I see your decade counter has an oscillator on the clock input comprising Capacitor (1uF) , Schmitt Nand 123 and the 1 meg resistor. Probably left alone the LEDs just sequence on (a sort of knight rider thing)

Anyway down to buisness.

So you want that when the S1 switch is depressed on your quiz circuit then this is counted by the decade counter.

Solution 1
As you see that when S1 is pressed the input into Pin 4 of IC2 goes from 0v (pulled low by R1) to Vcc (9v) i.e. positive going.

Your decade counter (4017) is clocked on pin 14 by a positive going waveform.

To clock the decade counter, simply disconnect (remove) the input to the counter (pin 14) and connect that to the jubnction of the switch, resistor R1 and pin 4 of IC in the quiz game circuit.

If done when you press S1 the input into your counter will go from low to high and your counter will clock on one.

If you still wish the LED on your counter to work then disconnect the output from the NAND gate (pin 3) on the decaded counter at the T junction of the second NAND gate and pin 14. And at that junction connect it to pin 4 of IC 2 (as before). When you press the S1 switch not only will it clock the counter but the 9v will be inverted by the second NAND and light the LED.

So that was the easy stuff. But be warned all may not be well. Switches have a tendancy to bounce and your counter may count more than once for each S1 key press, so you may need an antibounce circuit (a lockout circuit). However you can sometimes get a way with a capacitor. Just place a suitable value (it may require experimentation) across R1 on your quiz game circuit. When the key is pressed the capacitor will charge (an if small enough almost instantaneously) so any subsequent bounces will not be registered.

If it does not work then you may need to make an antibounce circuit using a NANd network.

Solution 2

Another method is to take the output from IC2 that lights the S1 LED. From the circuit it appears that pin three is the output and lights LED1. The output is Negative going in that it goes from high to low when you press the S1 key.

For you counter to count this, Remove the capacitor and resistor connected to pins 1&2 of the NAND gate on your decade counter and discard them.
Connect PIN3 of IC2 (4042) to pins 1&2 of the Schmitt triggered NAND on your counter.
When LED1 lamp lights (pin 3 low) this low is inveretd by the 1&2&3 pinned NAND and fed as a rise to the clock input of the counter and the counter clocks on one.

Differences between solutions

Solution 1 will count each time the S1 key is pressed.

Solution 2 will count each time S1 is pressed first.
i.e. providing its pressed before the other 3 keys. Any help ?, yes no let me know.

Regards

 

[T5]

thank you so so very much Laffalot.

one thing, when you talked about the lock out circuit, doesnt a Schmitt Trigger does this for you? a Schmitt Trigger is suppose give out a clean pulse when a pulse can get distorted.

thanx and laterz....

 

[xnuke]

I think Laffalot is referring to the fact that you didn't debounce any of the switches S1-S4 in the top schematic. A debounce (antibounce) circuit locks out electrical transients that occur during the closing of your switches to prevent problems from developing. You'll get a nicer transition from a logic 0 to a logic 1 if you debounce the switches.

 

[MMAshwin]

Hi,

Schmitt triggers are, as you stated, for cleaning up a distorted pulse however with switch bounce the switch is switching on and off very fast. A schmitt triggered IC would switch if the input pulse goes from Vcc to Vss as it does with switch bounce.

A lockout circuit need only be a couple of cross coupled NAND gates. As I said in the previous post you may get away with just having a capacitor. It charges up when the switch is closed. As the switch bounces and the voltage is removed, the voltage is supplied by the capacitor.

Any help ?, yes no let me know.

Regards

 

[T5]

hi there laffalot

i sent you an email regarding the quiz game circuit? did you receive it? i hope you could do the same for the one i mailed you.

thanx n laterz