Servo with timer help!?

[ezy172]

I want this circuit to have a switch so that once it is switched on the servo moves into position after a delay 4 seconds and stays there until it is switched off where it then returns to the orginal position. How could i do this with the following circuit?

[slipstick]

You can't directly. That's a circuit which allows you to manually control the servo position.

If you want automatic timed control between two pre-determined servo positions you'll need quite a bit more circuitry and components.

Steve

[AleG]

ezy32, you would need another timer, working on monostable mode to give you the 4 seconds delay. A 555 would come handy for that again. However that would only give you the delay, if you would wire up the delay timer to, let's say the reset pin (pin 4) of the IC then after the delay, the pin would go from 0 to 1 and the servo controlling 555 would start working and move the servo to the desired position. However the problem with that is that before the second 555 kicks in there's nothing to tell the servo where to stay. I guess you could use a relay two switch between to resistor values instead of the pot so you could change the pulse width of the 555...

Ugh, messy.

On the other hand it would be trivial to do it with a microcontroller. I think I could write up the code for all that in less than an hour, and I'm not even good at writing code. :rolleyes:

As a matter of fact, I'm working on a free flight dethermalizing timer that would do something similar. After a set amount of time the timer would command a servo to move something into dethermalizing mode. That part is quite easy to do, all the other bells and whistles take some more brain crunching though. :D

So... if you can program, or get someone to program for you an AVR microcontroller I think I can write the code for doing what you need.

[Acetronics]

Hi, Ezy

I think you could use a "Failsafe" device for one servo ( commercially existing )... like this one : http://www.futaba-rc.com/radioaccys/futm0992.html

just place your switch in the signal input wire (or use the 555 to tie signal to ground after the 4 sec ! ) ... :

signal enabled - the servo will follow the position given by a channel switch or pot of your Tx

signal cut - the servo will reach the PROGRAMMABLE position ...

Isn't it marvellous ???

Alain

[Tomapowa]

ezy172,
Best to keep all related questions/answers to this topic in one thread.... like here:

http://www.rcgroups.com/forums/showthread.php?t=963983