that you know a few of the basic 555 timer circuits to use in
your halloween animatronics, I'm going to show you how to use
them to build servo control circuits. We'll start with the basic
servo control circuit. You can use this circuit in your animatronics
to drive the servo from an adjustable starting point to the
maximum - really a 2 position control. Next we'll learn how
to automate this 2 postion control so that your servo will move
all by it'self.
animatronics will take a giant leap forward when you have several
of these automatic drivers working your prop And since we've
already went over how to build these these timer circuits, we
finally get a chance to use them. Now these are really cool.
Taking your circuits even further with the automatic 3 postion
servo driver. Im going to introduce a logic circuit - which
will drive the servo to each of the three postions randomly.
Great for natural non repeating movments to set your halloween
animatronics apart from the crowd!
we're going to make the prop simulate talking by using a really
handy circuit which takes recorded voice and uses it to switch
servo postions on the 2 postion servo control circuit Combining
all these different circuits gives you the tools needed to fully
automate and animate your animatronic props so Let's get started!
standard hobby servo needs 3 things to operate. Connection to
Ground, Postive voltage and finally a control signal. The control
signal is really a pulsed voltage, and we can use the Old Standby
555 astable circuit to create the control signal for the servo.
All we do is modify the Resistor and Capacitor Values and Voila...
a pulsed control signal from PIN 3, the output.
the long and short of it - For each servo postion you will need
a seperate Resistor values. So lets set up the first servo postion
Ok - Im going to make a quick drawing of the 555 circuit we're
going to use. Be sure to pick up a copy of Halloween Animatronics
Volume 1 for detailed explainations!
got the 555 chip in the middle, 4 and 8 are connected to postive
voltage Pin 5 has a .01microfarad capacitor connected and then
to ground Pin 1 goes directly to ground Pin2 and 6 are connected
together and then help form help our capacitance part of our
RC circuitry with the .1 microfarad capacitor
we get the the Resistor values. Pin seven will have a 220 kilo
ohm resitor between itself and our postive supply voltage Now
we also hook pin seven to a 4.7 kilo ohm resisitor and then
the other side of the 4.7 hooks directly to the pin 2 and 6
all that's left is pin three - our output pin In order to drive
the servo we feed this output to the base of a transistor This
circuit will creat the 1 millisecond pulse needed to drive a
servo to the start postion. A 1 ms pulse width will drive the
servo Left and a 2 ms pulse width will drive the servo to the
Right. So to get it in the middle you would need a 1.5 ms pulse
really easier than it may seem because the 555 does all the
work for you. So in order to animate something we will need
to be able to automatically switch back and forth between these
two resistor setups. We could build 2 seperate resistor circuits
and switch them by relay or by hand but an easier setup would
be to incorporate the 4066 CMOS switch.
before we add it to our schematic, Let me show you how it works.
THere are FOUR inputs Each INPUT acts kind of like a swtich
and closes two contacts.. Taking a closer look. say I apply
5 volts to pin 13 here That's what we call LOGIC HIGH as opposed
to LOGIC LOW or zero volts.
this LOGIC HIGH on pin 13 is going to tell the switch to close
contacts 1 to 2 and allow current to flow through those 2 outputs.
Take away the LOGIC HIGH and switch opens up. SO you can see
how using this chip adds a huge advantage to our circuit repitour
Adding the 4066 to our schematic is easy You can always get
a spec sheet of any of these chips off the internet if dont
have one. Here's the entire servo driver circuit Remember -
in order to make pins 11 and 10 close we need to apply a LOGIC
HIGH to pin 12
- How do we make this automate this servo driver? How get this
circuit set up so we can animate something Easy - Just add another
555 timer circuit. In Halloween Animatronics Volume One, there
is an entire section on building these servo driver circuits
plus you get to download all the BONUS files and schematics
so get your copy today! animatronics
downloads include 58 page FULL Color PDF - schematics - visio
drawings - PICBASIC codes and Bonus- Modding a Bucky PDF
just set Resistors and capacitor to get the timing we want.
The output of PIN 3 will connect to Our INPUT PIN on the 4066.
- Now we got automation - I've built the first part of the servo
driver circuit - But it's always a good idea to test your circuit
as you go along.
are the 2 wires I will connect to the 4066. touching them together
simulates what the 4066 will do when a LOGIC HIGH voltage is
applied to their input pin. Here's a closer look at the servodriver
circuit. With a minimum of space and components - this circuit
is a staple in my electrical Halloween animatronics.
used a 16 pin chip holder because I knew I wanted to mount 2
555's This servo header can accomodate up to 6 servos I have
supplied part numbers for ordering lots of these components
on the downloadable schematics Now that I have all the components
in place Its time to make some adjustments I can adjust the
amount of time between servo postion movements You can also
adjust the postion of the servo arm.
Ok so this is an automated 2 postion servo controller. Let's
see what it can do. I have it driving the PAN motion of this
ANIMATRONIC NECK skeleton. Now I say skeleton because all it
is right now is an aluminum skeleton which will serve as the
Neck joint in one of my animatronic designs.
you can see, the circuit will drive any of the servos on this
design. But Sometimes you need more than the 2 postion servo
controller. Sometimes you need 3 - and sometimes you need a
random element Randomness emulates life, and adds more realism
to your prop motions. Lets take a look at what I call the 3
postion servo controller
here to go to micro-controllers and computer control section