I am just curious.
You want something that will turn to the angle you instruct and then return to zero when you are done.
Can you use a standard hobby servo and simply command it to go to zero before your program is done?
Yelectric:
this is to simplify a mechatronics project to not require a microcontroller.
I can't see how you could do that.
With a simple non-geared DC motor you could arrange a centering spring but you have no simple means (other than a physical end-stop) to determine how far it goes.
With a servo you can easily control the distance moved but you could not use a return spring. It would have to be a very strong spring to overcome the resistance of the gear train. Being so strong its repeated use would probably damage the gear train. And its strength would overload the motor when it was powered, probably causing the motor to overheat and be destroyed.
You can control a servo with a very small microprocessor.
If I'd take the challenge to design this without a microcontroller, but with a hobby servo, first I'd need the internal power source, which could provide the voltage and the amps for a second or two for the servo to operate after the external power is removed. Some juicy capacitor might do that.
The circuit would have a rectifyer to get the input power right. The rectified input power would provide power to a circuit including a few timer chips to produce a pulse with the perfect length to get the servo to the right angle. There are two angles to reach, 50 degrees or 130 degrees, depending ov the polarity of the input power. Some more components needed to have the polarity to select the needed pulse length. And some trimpots for adjusting the angles correctly. And then when the input voltage goes to zero, the internal power kicks in and produces the third pulse length corresponding to 90 degrees. Some diodes, some transistors, to get the three different states working.
But I won't take the challenge. To me, this is not simplifying things. To me, an Arduino Beetle is what would simplify things. Or any Arduino, actually.