how can I disable a clock in 555 and 4040?

[ikelectro]

i'm using 4040 and i give pulse to it with a 555. how can i disable the clock wherever i want. suppose i want to disable the clock after 255 or 11111111. remember I dont want to reset, I want to disable the clock to stop pulsing 555, so the 4040 IC.
plz friends help me out.

 

[kubeek]

You can stop the 555 by holding it´s reset pin low.

 

[ronsimpson]

From post #2 we know that the reset pin needs to go low to stop the 555.
The 4040 has Qx outputs that start out low and after some counts go high.
If we connect a output Q through a 10k resistor to the base of a 2N2222a transistor, emitter on ground, and collector on the reset pin of the 555. When Q goes high the transistor will pull the reset (555) low?

Is that what you want?

 

[KJ6EAD]

To disable the clock at a specified count, you would need to decode the 4040 outputs for the specified value.

 

[ikelectro]

From post #2 we know that the reset pin needs to go low to stop the 555.
The 4040 has Qx outputs that start out low and after some counts go high.
If we connect a output Q through a 10k resistor to the base of a 2N2222a transistor, emitter on ground, and collector on the reset pin of the 555. When Q goes high the transistor will pull the reset (555) low?

Is that what you want?

i want to disable the clock. in that process can the reset pin of 555 will constantly low. more clearly i can say that i want to hold the the clock or no more pulsing state after 11111111(output of 4040).

 

[ikelectro]

You can stop the 555 by holding it´s reset pin low.

but how can i hold it. that is my question!! i dnt want it manual.
after 4040 output reches to 255 i want to hold the clock.

 

[alec_t]

Use an 8-input NAND gate. Q outputs from the 4040 are the gate inputs. Gate output connects to 555 reset pin.

 

[ikelectro]

Use an 8-input NAND gate. Q outputs from the 4040 are the gate inputs. Gate output connects to 555 reset pin.

will it hold the clock????

 

[ronsimpson]

i want to disable the clock. in that process can the reset pin of 555 will constantly low. more clearly i can say that i want to hold the the clock or no more pulsing state after 11111111(output of 4040).

How clear can I say, if you hold down the reset pin of the 555 it will hold the clock. The 555 will stop clocking and thus the 4040 will also hold.

If the 4040 is at 0000,1111,1111 one more clock will be 0001,0000,0000. Use the 1 to stop the 555. In your example you said "11111111" and "100000000" is only one more than your example.

 

[Roff]

How clear can I say, if you hold down the reset pin of the 555 it will hold the clock. The 555 will stop clocking and thus the 4040 will also hold.

If the 4040 is at 0000,1111,1111 one more clock will be 0001,0000,0000. Use the 1 to stop the 555. In your example you said "11111111" and "100000000" is only one more than your example.

Yeah, but that's 256.
EDIT: I realize that you did say that it is only one more count.

 

[ikelectro]

sunddenly comes to mind that i can do it with also a 8 bit comparator. so i use a 74LS688. that's out put is remain high until all thr paramtr are same, if same then go to low. so, i connected it with the pin no. 4 of 555. that works nicely.thanks everybody.