Hi,
I need to produce a squarewave signal which is between +12V and -12V
I just need to control duyt ratio, nothing else.
Anyone can help me for this case with IC or circiut diagram suggestion
Thanks in advance

 

You can make a square wave generator using a basic op-amp circuit. Just google op-amp signal generator. If you need ±12V and your supply is also ±12V, you'll need to choose an op-amp that can output rail-to-rail. Most can only get within a couple volts of one rail or the other, or both. If you have a ±15V supply, just about any op-amp will do, at low frequency. If you need more that 1kHz or so, you'll also need to be sure to choose a faster op-amp.

 

Here is my favorite constant frequency, variable duty cycle circuit. The 555 will only stand supply of voltages of ~18V, so if you really need +-12V, you may choose to put a rail-to-rail opamp with a gain ~2 behind it.

 

thanks for your advices,
rail to rail almost solved my problem,
one more think is, the output of opamp is connected to 2k ohm empedance. That makes the positive side 11,5V, (0,5V voltage drop). I simulated it with LMC 662.
Is there any other opamp IC that can handle with this output current with lover voltage drop level.

 

Sure, look for a high voltage, rail-to-rail, OpAmp in TI's Parametric Selection Tool

http://www.ti.com/ww/en/parametric_selection_tool/index.html