There is a sneaky and devious thing you can do with the CMOS version of the 555 that could be advantageous here.

An astable multivibrator can be built in the usual way except for the resistors. A single resistor is used between the output and the timing capacitor. When the output is low, the capacitor is discharged to the trigger level, setting the output high. The cap now charges to the threshold level, sending the output back low. The duty cycle, except for the first cycle, is very close to 50%. If you put a pullup resistor on the discharge pin, it becomes the logical complement of the output pin, so you could drive one N-FET with the discharge pin and another with the output pin.

[Edit] You can do this with the bipolar (ordinary) version of the 555, but the duty cycle won't be 50% because the output HIGH voltage is less than the supply voltage. The higher the supply voltage, the closer the duty cycle will be to 50% because the difference between the output HIGH voltage and the supply voltage is more or less constant.

see Figure 17
http://www.ti.com/lit/ds/symlink/lmc555.pdf

Thanks, I think I'll try that.

 

I tried to redraw a circuit, but I don't understand why you want to use relay at the left top.

What is the LM317?
If the LM317 is a adjustable regulator then the symbol was wrong and the values of R3 and R4 will be too high, if it is a transistor then do you have a datasheet?

If the LM317 is a transistor then why do you want to use it?

How is the values of R2, if it is a 5.1M then the values is too high for a transistor type, you should use the CMOS type as TLC555 or LMC555 or ICM7555.

 

I tried to redraw a circuit, but I don't understand why you want to use relay at the left top.

What is the LM317?
If the LM317 is a adjustable regulator then the symbol was wrong and the values of R3 and R4 will be too high, if it is a transistor then do you have a datasheet?

If the LM317 is a transistor then why do you want to use it?

How is the values of R2, if it is a 5.1M then the values is too high for a transistor type, you should use the CMOS type as TLC555 or LMC555 or ICM7555.

View attachment 147840

That relay is not necessary anymore and thanks for correction on LM317. It is a voltage regulator and I used the wrong symbol. Also I do have the data sheet and I corrected those values.
R2 is actually 5.1M and it worked fine but I got the value from a 555 calculator and I didn't know if it was right.
Thanks for the circuit, that looks like what I want so I going to try it.