Led delay circuit

[yusuf]

I have attache the circuit in my attachment..

it's the bistable and timer circuit...

In circuit when the manual start button is pressed the 4060 timer starts to run..

As the preset time is elapsed , pin 3 (Q14) of 4060 timer circuit unlatch the bistable circuit via D2 and turn off the 4060 timer circuit.

Within this process , as the output pin 3(Q14) of 4060 timer circuit goes high the red led(led 3) just flashes and turned off.


All is fine except the red led flashes and turnes off...
I want to glow red led (LED 3) to 2 - 3 second...

thanks

 

[ronv]

When Q14 goes high it also resets the counter so it is only high for a very short period of time. I'm suprised you can see it.

 

[yusuf]

When Q14 goes high it also resets the counter so it is only high for a very short period of time. I'm suprised you can see it.

Ya I know ronv..
The problem is the led is high for a short period of time...

But I want to turn on the red led(led 3) to 2 - 3 second..... before resetting the counter..

 

[ronv]

Try something like this:

 

[yusuf]

Try something like this:

Ok but where should I connect the led..

Is it after R1 or at the joints on R1 and C1.

And can you give me some explanation of this circuit..
How will it going to work...

 

[ronv]

The LED stays on Q14.

The way it works is:
Q14 goes high the capacitor is slowly charged thru the resistor.
This delays the reset so Q14 stays high longer.

 

[yusuf]

ok thanks ron...

Ron Can you explain what is the use of diode in this logic circuit..
As you can see above that to work properly some diode are used to take high /low the ic pins..

So some question comes in my mind are :

IF I WANT TO LOW / HIGH THE IC(ANY LOGIC IC) PIN THEN HOW DO I PLACE DIODE.

HELP WILL BE APPRICATED

 

[ronv]

I have to go now but will be back in about 2 hours.

 

[yusuf]

i have to go now but will be back in about 2 hours.

ok , well thanks for your valuable help friend

 

[ronv]

Logic

Here is an example. I call it a - OR, because if either input a OR input b is minus the output of the transistor will be plus.

The diode will only conduct when the cathode is negitive with respect to the anode and that is what makes it work. There used to be a whole logic family built kike this.