Heat damper control

Just a little description of the heat servo control that I have been working on.

I thought it would be nice to have a electric control knob for the front and rear seat heat instead of the old push pull cable setup.

I used a standard radio control servo so that if I ever needed to replace it I could find one at a reasonable price. ($10-$15)

The servo requires a series of pulses sent to it for position information.

The length of the pulse is the part that determines the position of the control output.

The range needed it 0.6 milliseconds when the control arm is -45deg and 2.4milliseconds when it is +45deg.

The frequency of the the pulses are not that important.  They will work fine with a frequency range anywhere between about 400Hz (2.5miliseconds) all the way to 50Hz (20milliseconds)

To draw the circuit I used a computer program that will let you draw a circuit schematic and then it Will auto route the circuits for the circuit board layout.

After I had the layout fixed up like  wanted it I printed it on a sheet of glossy magazine paper.  The reason for this is that the toner from the printer does not stick well to the paper.

Then I laid the paper upside down on a sheet of copper clad fiber board.  Using a houshold Iron I pressed the magazine paper face down on the copper.  This melted the toner (a plastic) onto the copper.

After that I soaked the paper in water for about 1hr until it was soft.  At this time i very carefully pealed the paper off leaving the melted toner traces on the copper board.

Then I mixed up a solution of hydrogen peroxide and muric acid.  this makes a chemical that is very corrosive to copper. I soaked the copper board in the solution until all the visible copper was dissolved from the exposed surface.

After that I rinsed the board in water to make sure there was not any acid left on it and then took a rag dipped in acetone and wiped the melted toner off the board leaving the nice little circuit traces.

This provided me with a nice little circuit board to mount the components on for operating the servo.

At the top of this blog is a banner that has You tube movies on it.  If you want to see the finished product working find the on that says Servo Controller.