Direct control of a Servo for Halloween?

[WantonZoo]

Hi all - I want to use a servo to move a model for a small head on my
shoulder. You know - my evil - attached to my shoulder twin? Anyhoo - is
there a way/simple circuit to control a servo without using RC reciever,
etc. Just a direct push button a it turns left then button b it turns
right?

 

[Chris]

Hi all - I want to use a servo to move a model for a small head on my
shoulder. You know - my evil - attached to my shoulder twin? Anyhoo - is
there a way/simple circuit to control a servo without using RC reciever,
etc. Just a direct push button a it turns left then button b it turns
right?

Hi, Wanton. You and your evil twin will appreciate this hobbyist
circuit for making a servo control pulse from an LM556 (or two LM555s):

http://www.seattlerobotics.org/encoder/200210/servoex/ServoExcerciser.htm

A servo accepts a control pulse every 20ms. or so. The active-high
pulse width is the position control (the wider the pulse, the more
angle).

Just use a 10K resistor instead of the 10K pot on the 2nd 555, and
place your switch contacts across the 10K resistor. When the switch is
closed, the pulse will be short (and the head will move toward you).
When the switch is open, the pulse will be long (and your evil twin's
head will move away). This circuit provides two position control,
where the servo will travel end-to-end.

Simple circuit, runs off your servo's power supply, and all components
are commonly available at any hobbyist source, including Radio Shack.

Good luck
Chris

 

[Bob Masta]

Hi all - I want to use a servo to move a model for a small head on my
shoulder. You know - my evil - attached to my shoulder twin? Anyhoo - is
there a way/simple circuit to control a servo without using RC reciever,
etc. Just a direct push button a it turns left then button b it turns
right?

Heck, why not skip the servo and just have a reversible DC motor
(geared down appropriately)? Think of all the cheap kids' toys that
do all sorts of antics with nothing more complex than that (plus maybe
a few clever linkage arms, etc).

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

[WantonZoo]

Exactly smackly. Instead of building a circuit I could hack a cheap RC
something and animate the head that way. Or simply take one of those heads
in a ball they have in the stores right now and stick it to my shoulder.
Thanks -

 

[jasen]

Hi all - I want to use a servo to move a model for a small head on my
shoulder. You know - my evil - attached to my shoulder twin? Anyhoo - is
there a way/simple circuit to control a servo without using RC reciever,
etc. Just a direct push button a it turns left then button b it turns
right?

yup. you need to generate a pulse width modulated signal.
one way to do this is using a chip called a 555 (which is cheap),
an a few other cheap parts. have you encountered this chip before?

if you don't have a servo yet, consider using a central-locking
actuator as they are cheaper easier to drive.

Bye.
Jasen

 

[Si Ballenger]

Exactly smackly. Instead of building a circuit I could hack a cheap RC
something and animate the head that way. Or simply take one of those heads
in a ball they have in the stores right now and stick it to my shoulder.
Thanks -

The "DollarTree" store has little wire controlled battery powered
cars for $1 that have foward and reverse buttons on the 2 AA
battery control. Easy hack to have the axel move a light head
left and right.

 

[Bob Masta]

The "DollarTree" store has little wire controlled battery powered
cars for $1 that have foward and reverse buttons on the 2 AA
battery control. Easy hack to have the axel move a light head
left and right.

The car wheels probably move a lot faster than you want the
head to move, so you can gear down the wheel motion and
have plenty of torque to turn the head. In fact, skip the gear
reduction: Pop the wheels off and use a bare axle as the
drive, and put the head on a shaft that can take the wheel
(assuming it is soft rubber). Now the motor shaft drives the
rubber wheel by friction, giving a huge "gear" reduction and
having an automatic clutch action. The slower speed will
make it a *lot* more creepy!

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator