Hi,
I Have Output voltage of 7.67v and i put 240 and 270 ohm resistor to divide the voltage...
but instead of 3.7v output, its 2.2v...
Why ??

 

Double check your input voltage. If it's from a battery then it will drop when loaded.

 

What do you mean its will drop when loaded ?
its from 7v of 555 timer

 

Post your circuit. Where is the 7V coming from? A 555 timer is not a voltage source. If the source is a battery and it is old or weak, when power is requested from it, the voltage output may go lower. Think of a flashlight with weak batteries. The light gets dimmer because the weak batteries can not supply the proper voltage/current.

 

Its output from 555 as monostable....
And the battery stay stable,
The voltage divider splits the voltage to 5.44 and 2.23 (together 7.68), instead of 3.622v and 4.058v....

 

I would double check the resistor values then.

 

I Double checked it, its 233 ohm and 261 ohm,
Still the voltage is not make sense....

 

Measure the out put voltage at the 555 with the divider in use and see what that voltage is(this will be the actual input voltage to the divider, you can then refigure you divider using that voltage.)

 

Dont understand what you said...
The circuit is ok, why its different volts??

 

The 555 has an output impedance of its own which will cause its output voltage to drop some when it is loaded. As shortbus said, measure the output voltage of the 555 with the divider connected.

 

I Just did!
its 7.68v....

 

I still want to see a schematic...

 

If the source is a battery and it is old or weak, when power is requested from it, the voltage output may go lower.

Thanks,
mail forwarding

 

the voltage is not going lower....
The resistors divide it into 5.44 and 2.239...
Thats mean the battery is full!

 

Problem Solved!
I Used LED indicator, and I think its do some trouble while measuring volts...

 

Proper test methods means a lot. How many of us old timers have never done anything like that????

By the way, ...... What kind of LED voltmeter do you have that will read 3.7 volts or 2.2 volts or do you mean you had an LED tied to the circuit? If so, the LED was loading the circuit to its forward voltage drop.