I have a problem that is the following:
I have to control a servo motor between 3 positions, and i already can make the PWM signals to make the servo motor go to this 3 positions but i want to if i press one of two buttons the servo go to 1 position and when i drop the button the servo motor go to a default position and is the same for the other button, when i press go to the defined position and when i drop the button go to the default position!
And i make a logic circuit with the AND, XOR gates to control this process and doesnt work, someone can give a opinion or other path to make this idea ?
Thank you.

 

How does the controller know the motor position? You need some sort of feedback. A potentiometer, a rotary encoder or possibly simple position switches.

 

Is this a RC servo or an industrial motion control type.?

 

It is a RC servo!

 

How does the controller know the motor position? You need some sort of feedback. A potentiometer, a rotary encoder or possibly simple position switches.

The controller doesnt need to know the motor position, i only have to conect the right resistor to the discharge pin when the button is pressed.

 

Is the default position between the two defined positions, or is it clockwise/counter-clockwise to both? Two resistors switched in series or parallel with a default resistor may be sufficient for setting the pulse widths.

 

the default position is between the two defined positions.

 

In that case the circuit below should work. The resistor values would need tweaking to suit the 3 positions required.
Note that the pulses are negative-going, S1 is a NO type and S2 is a NC type.
Inverters could be added to invert the pulse polarity and S2 logic if wanted.


LTspice sim file attached.

 

In that case the circuit below should work. The resistor values would need tweaking to suit the 3 positions required.
Note that the pulses are negative-going, S1 is a NO type and S2 is a NC type.
Inverters could be added to invert the pulse polarity and S2 logic if wanted.
View attachment 259447

LTspice sim file attached.

Sorry i forgot to refer, but i can't use micro controllers and NC switches.
I only have transistors and logic gates to solve the problem.

 

Is this a school/college project?

 

https://hackaday.com/2021/05/11/smallest-discrete-transistor-555-timer/
https://0creativeengineering0.blogspot.com/2018/12/discrete-555.html

 

I only have transistors and logic gates to solve the problem.

So why does your post#1 schematic include a '555 ?

Edit:
Providing you can tolerate a ~3% variation of pulse width over a 10-50 °C temperature range, then a much simpler circuit using just 1 logic gate, 1 diode, 2 caps, 3 resistors and 2 NO switches could be used.