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555 Timer for 1 Hz with 0.1 % duty cycle.

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amayilsamy

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How to make 555 Astable multivibrater for 1 Hz?

Duty Cycle On Time=0.1 ms, Off time=999.9 ms.


Or Which is the best way for 0.1 % duty cycle in 1 Hz.


Thanks in advance.....
 

One good way is to use two 555 (or one dual 556) timers. The first is an astable with a 1s period. This triggers the second 555 which is connected as a one-shot (monostable) with a 0.1ms period.
 

Each pulse is .001 second long, at a time period of 1 Hz.

Just to see if it is possible, I tried it with a single 555. With careful adjustment I managed to get pulses .002 sec long.



The scope traces show that the capacitor charges and discharges inside a range of 26 mV. That is how small the adjustment gets, in order to obtain the narrow duty cycle.

Furthermore a change in duty cycle causes a change in overall time period, and vice versa.

Crutschow's recommendation of two 555's will be easier to get right. The time periods can be adjusted independently of the other.
 

Thanks for Both of you.

How it possible in dual timers. Help me out how to do it. I need exactly 0.1 ms on time in 1 Hz....
 

You could use standard astable circuit below with:
R1 = 2.2 Megohms
R2 = 220 Ohms
C = 0.68uF

That should oscillate at about 1Hz, with time high = 1S and time low = 0.1mS.

To get the waveform you want, just invert the output from the 555. You can use another 555 as an inverter.

 
I already do it with single timer. Can't achieve 0.1 % in 1 Hz. Its 0.4% in 1.025 Hz. So, I need near than 0.1 % in 1 Hz with maximum 2% errors.
 

amayilsamy said:
I already do it with single timer. Can't achieve 0.1 % in 1 Hz. Its 0.4% in 1.025 Hz. So, I need near than 0.1 % in 1 Hz with maximum 2% errors.
Click to expand...
For that accuracy you will either have to go to a crystal controlled oscillator and counter or use trimpots to tweak the resistor values for the 555 to get the desired frequency and period.
 

Do it with a 8-pin micro. Then sand off the top of the micro and write 555 on top :0)
 

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