555 Timer Servo Control with Push Button and Auto Return

[mactonight]

Hi everyone,
I'm working on a servo motor control circuit using a 555 timer. I have the following circuit (attach the schematic if possible). When I remove the button connected to the 68k resistor, the servo moves to 180° but does not return to 0°.

What I want to achieve:

• When I press the button once, the servo should move to 180°.
• It should stay in that position for 1-2 seconds.
• Then, it should automatically return to 0° without pressing the button again.
• I cannot use an Arduino, so I need a fully analog solution.

How can I achieve this using a 555 timer or additional components? Should I use a monostable, bistable, or another approach?
Any suggestions would be greatly appreciated.

Thanks in advance!

 

[Nigel Goodwin]

With no button pressed the 555 doesn't work, there's no timing resistor - you need to add a resistor between pins 7 and 6 to set the return point. However, it won't hold for 2 seconds (only while you hold the key down), you would need an extra 555, and extra complications to make it timed.

Presumably this is a school project?, hence not using a micro-controller which is the far more obvious and simpler solution.

 

[mactonight]

With no button pressed the 555 doesn't work, there's no timing resistor - you need to add a resistor between pins 7 and 6 to set the return point. However, it won't hold for 2 seconds (only while you hold the key down), you would need an extra 555, and extra complications to make it timed.

Presumably this is a school project?, hence not using a micro-controller which is the far more obvious and simpler solution.

i'm an intern student and yes this is like kinda homework and i cant use microcontroller

 

[danadak]

You could use a dual 555, press of button triggers one to set a D flip flop, and
triggers the second 2 sec 555. It in turn after 2 sec resets the flip flop.

Then use another 555 (ugh) to get the servo 2 mS waveform to position the
servo.

Partsy to say the least. A single ATTINY85 8 pin micro, which is a collection of analog
and logic, like a 555 is as well.

If the prof wants to you to use old school why not vacuum tubes, or magamps.....
or relay logic or.....dont ask him that....

You could use the tiny, and pot it after coding so it cant be seen........hide it in a brown paper bag.....