Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Change in Duty Cycle.

Status
Not open for further replies.

ikelectro

Member
I'm using CD4060 with a 32.768 crystal and I have to change the Duty cycle for the output. But don't know how to change the duty cycle in CD4060!!1:confused:

Need your help......
 
ok thank you... I'll do it in the bread board. if any problem occurs i'll post that here!!! ok?
 
At exactly what signal point in the circuit do you need this duty-cycle?
 
At exactly what signal point in the circuit do you need this duty-cycle?

actually I need either 99.97% or 0.03% duty cycle in 1sec clock pulse. I don't have to vary. I should have been tell it before. sorry for the mistake. this clock pulse I'll give to CD4026 to enable and disable the clock.....
 
actually I need either 99.97% or 0.03% duty cycle in 1sec clock pulse. I don't have to vary. I should have been tell it before. sorry for the mistake. this clock pulse I'll give to CD4026 to enable and disable the clock.....
One way to do that is to use the 1 sec pulse to trigger a one-shot (such as using a 555) with the desired pulse-width.
 
One way to do that is to use the 1 sec pulse to trigger a one-shot (such as using a 555) with the desired pulse-width.

but 555 is not very good about to give 1 sec pulse. depend upon the resistor and capacitor which are also temperature depended. I need exact 1 sec pulse all the time with that duty cycle!!!! I have to think with crystal! what do you say????:confused:
 
Last edited:
but 555 is not very good about to give 1 sec pulse. depend upon the resistor and capacitor which are also temperature depended. I need exact 1 sec pulse all the time with that duty cycle!!!! I have to think with crystal! what do you say????:confused:
You missed Zapper's point: You use the output of the divider chain (1sec square wave) to trigger a one-shot (any will do) You set the RC time-constant in the one-shot to be ~3ms, ero it puts out a 3ms pulse once per every 1000ms, where the one second period is locked to the crystal.

Or build a one-shot out of a cmos schmitt-trigger inverter:
 
Last edited:
but 555 is not very good about to give 1 sec pulse. depend upon the resistor and capacitor which are also temperature depended. I need exact 1 sec pulse all the time with that duty cycle!!!! I have to think with crystal! what do you say????:confused:

The 555 can be used with a crystal just like the CMOS inverter you are using now.
View attachment 68778

That does not change the fact that to get the variable duty cycle that you want, it would be better to go with what has been suggested instead of trying to pull the crystal there (even if that range is even possible).

John
 
He wants to create the 3% duty cycle at the 1Hz output of his divider chain, not at the crystal.
 
He wants to create the 3% duty cycle at the 1Hz output of his divider chain, not at the crystal.

I know that. I was referring to the second post in this thread, which didn't strike me as a good idea at the time, but I saw no reason to comment then. My comment was then sparked by the OP's assertion that the 555 was inherently a poor timer. In fact, it is no worse than any other inverter-based relaxation timer. Moreover, it can also be crystal controlled.

John
 
You missed Zapper's point: You use the output of the divider chain (1sec square wave) to trigger a one-shot (any will do) You set the RC time-constant in the one-shot to be ~3ms, ero it puts out a 3ms pulse once per every 1000ms, where the one second period is locked to the crystal.

Or build a one-shot out of a cmos schmitt-trigger inverter:

yes yes. now I get it!
thanks both of you....
 
You missed Zapper's point: You use the output of the divider chain (1sec square wave) to trigger a one-shot (any will do) You set the RC time-constant in the one-shot to be ~3ms, ero it puts out a 3ms pulse once per every 1000ms, where the one second period is locked to the crystal.

Or build a one-shot out of a cmos schmitt-trigger inverter:
oki'll try your circuit. if you don't mind can you please explain what does the diode 1N914 is doing here.
i'm just 1 year lod with electronics!!!
 
He wants to create the 3% duty cycle at the 1Hz output of his divider chain, not at the crystal.

no no. not 3% i want it 0.03%
 
The 555 can be used with a crystal just like the CMOS inverter you are using now.
View attachment 68778

That does not change the fact that to get the variable duty cycle that you want, it would be better to go with what has been suggested instead of trying to pull the crystal there (even if that range is even possible).

John

woW!! I didn't know before that 555 can be used with a crystal!!!!
i'll definitely do it in bread board!! thanks for the nice informartion.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top