Push button to toggle servo direction - monostable 555 circuit?

I would like to build a circuit where I push a button once and a servo moves 180 degrees and stays there.  If I push the button again it should move back to the start position.

A switch is good alternative, whichever would be easier.

I've been looking at circuits to do with 555 timers and servos and have found these two which seem useful:
http://www.555-timer-circuits.com/servo-controller.html
http://www.dummies.com/how-to/content/electronics-components-555-timer-chip-in-monostabl.html

Is that second circuit what I need?  How would I change the direction of the servo each time it runs?

I looked into flip-flops such as the 4013 which came up as a suggestion instead of a 555 but quickly got out of my depth.  I'm happy tinkering around with electronics but unfortunately don't know too much of the theory...

A monostable 555 circuit is the perfect option. But a single monostable will only run the servo in a single direction. So you'll need a second monostable circuit wired to the servo with the power reversed to move it back. You'll want to take the time to understand how a flip flop works cause that will be the best way to flip between your 2 monostable 555 timer circuits and move the servo like you want. You can get a 556 which is a pair of 555 timers in a single IC.

Use this basic flip flop circuit minus the LEDs and 470 Ohm resistors. Instead run the leads that would connect to the resistors and LEDs to the 2 monostable 555 circuits where the power would go into the circuit. So when you push the button power will go to the green side powering the 555 circuit to move the servo one way. Press the button again and the power flips over to the red side powering the other 555 circuit moving the servo back.
Sparrowhawk (author)  mpilchfamily4 years ago
Thanks that seems great... I'll give it a go!
iceng4 years ago
A simple bi-directional servo tester.
servoTest.gif