Ideas on a simple project please - rotating small dalek!

[[email protected]]

Hi all,

I have somehow promised to make, what I'm sure for others is, a very
simple project - but I have never done anything like this and would
really appreciate some suggestions on the best way to do so.

Aim
A highly controllable rotating display 'table', about 8 inches in
diameter, capable of holding a toy dalek (12" height, weighting
1Kg?). Must be able to smoothly rotate the dalek at least 180
degrees, although more is fine. I'm looking for a gentle, controlled
rotation. The user should be able to rotate the table clockwise and/or
anti-clockwise in small steps at will. The rotation speed not very
important - maybe 180 degrees between 5 and 20 seconds?

(The idea is to hide the table and make it look like the dalek is
looking/following a person.)

Requirement.
Low voltage - 6V, 9V or 12V battery.
The control unit must be remote from the table, up to 5 meters away,
cable connection.
On the control unit, a method of rotating the table clockwise or
anti-clockwise. Also a stop position.
Somewhere a master on/off switch.

Very happy to buy a Lego / Meccano / self assembly kit, if this has
every thing I need. Alternatively where should I go to get the motor
and a speed controller? Or do I need gear cogs? Or maybe what I need
is name of a good book to start with!

Any help/pointers gratefully received.

Bryan

 

[John Popelish]

Hi all,

I have somehow promised to make, what I'm sure for others is, a very
simple project - but I have never done anything like this and would
really appreciate some suggestions on the best way to do so.

Aim
A highly controllable rotating display 'table', about 8 inches in
diameter, capable of holding a toy dalek (12" height, weighting
1Kg?). Must be able to smoothly rotate the dalek at least 180
degrees, although more is fine. I'm looking for a gentle, controlled
rotation. The user should be able to rotate the table clockwise and/or
anti-clockwise in small steps at will. The rotation speed not very
important - maybe 180 degrees between 5 and 20 seconds?

(The idea is to hide the table and make it look like the dalek is
looking/following a person.)

Requirement.
Low voltage - 6V, 9V or 12V battery.
The control unit must be remote from the table, up to 5 meters away,
cable connection.
On the control unit, a method of rotating the table clockwise or
anti-clockwise. Also a stop position.
Somewhere a master on/off switch.

I suggest a servo unit intended to control the flight
surfaces of model airplanes. They are made in many sizes,
have smooth, proportional response, include the reduction
gears to provide relatively high torque, have the right
voltage requirements and move fast enough for this.
http://www.futaba-rc.com/servos/index.html

 

[default]

Hi all,

I have somehow promised to make, what I'm sure for others is, a very
simple project - but I have never done anything like this and would
really appreciate some suggestions on the best way to do so.

Aim
A highly controllable rotating display 'table', about 8 inches in
diameter, capable of holding a toy dalek (12" height, weighting
1Kg?). Must be able to smoothly rotate the dalek at least 180
degrees, although more is fine. I'm looking for a gentle, controlled
rotation. The user should be able to rotate the table clockwise and/or
anti-clockwise in small steps at will. The rotation speed not very
important - maybe 180 degrees between 5 and 20 seconds?

(The idea is to hide the table and make it look like the dalek is
looking/following a person.)

Requirement.
Low voltage - 6V, 9V or 12V battery.
The control unit must be remote from the table, up to 5 meters away,
cable connection.
On the control unit, a method of rotating the table clockwise or
anti-clockwise. Also a stop position.
Somewhere a master on/off switch.

Very happy to buy a Lego / Meccano / self assembly kit, if this has
every thing I need. Alternatively where should I go to get the motor
and a speed controller? Or do I need gear cogs? Or maybe what I need
is name of a good book to start with!

Any help/pointers gratefully received.

Bryan

Model servos work over a range of about 270 degrees and are reasonably
priced compared to DIY. Tower Hobbies will probably have the best
prices. They are on the 'net.

You need a circuit to actuate it. They take pulse position modulation
to set the position. For that a "servo tester" would work for you.

Simple servo tester schematic
http://homepage.ntlworld.com/g0xan/graphics/robots/servo_test.gif

You may also want to consider a "thrust bearing" to bear the load of
the table and contents - the servo isn't optimized for a load directly
on it's shaft - for that you need something like a lazy susan bearing
to support the weight of the table.

 

[BobG]

The RC servo will work like an Owl's head if the guy walks around it
in a circle. Better to have a little micromo gearhead motor with an
encoder on the back of it... run a couple of wires from the 5v dc
motor and the encoder to a little microcontroller. (I'm a programmer.
All the problems I solve have a microcontroller in the solution). Add
Passive Infrared Sensors in the eyeballs and the darn thing will track
anything hot autonomously.

 

[default]

The RC servo will work like an Owl's head if the guy walks around it
in a circle. Better to have a little micromo gearhead motor with an
encoder on the back of it... run a couple of wires from the 5v dc
motor and the encoder to a little microcontroller. (I'm a programmer.
All the problems I solve have a microcontroller in the solution). Add
Passive Infrared Sensors in the eyeballs and the darn thing will track
anything hot autonomously.

Good idea.

He expressed the idea that he's not too into electronics and wanted it
simple. Learning a pic may be outside the scope of the project.

I made a remote positioner from a pair of stepper motors. One stepper
generates the signal and the other follows the first. An quad op amp
takes the signal one motor generates, and turns it into a square wave
drives for a few Darlington power transistors. Turn the knob on the
generator and the slave follows it. I used a pair of cheap surplus
bipolar steppers of the same type, but could have also used ones with
different step angles for more or less fine control of the driven
motor. Really worked well for a remote antenna tuner.