Fiddle Yard

User pagesFred Jansen

Mechanical construction

The Fiddle Yard is built in wood. The surface is on the photograph not yet placed. 15 tracks will find there places on the surface.
A simple steppermotor is used,that is why i tried to make the constructon not too heavy.

The bearing

For a smooth going of the FY i applied a kind of linear ball bearing units. The ones used in cabinet drawers.
The maximum drawing aside is about 50cm to the left and 50cm to the right.

As zero position indicator a simple microswitch is used.
This microswitch takes care off the same starting point, every time the fiddle yard starts up.

The stepper motor

As drive I used an old steppermotor out of an old HP printer. The drive belt is cut and gives us a length of about 60 cm, that is enough for the lateral movement. The steppermotor is hinge fastened. The drive belt goes along two guide rails, also from the HP. A spring keeps tension on the drive belt. The steppermotor is fastened to the moving part of the FY, the drive belt is fastened to the fixed part.

An overview of the electronics used.

The DC powersupply for the steppermotor is not on the photo. The program and the positions are stored in a Pic. That is why every position of the track on the surface of the FY is free programmable. The speed of the steppermotor rises when starting and declines when stopping. So the trains will not fall off.!The moving speed can be controlled in 15 steps.

For the PCB, the schematic ( KiCad )and the sourcecode for the PIC see:

Some construction details

  • The PCB is single sided.
  • The dual 7segment display shows us the number of the position and the moving speed
  • Data I/O is opto-isolated
  • A Led indicates if the position is reached.
  • A simple control panel to program the positions
  • Postionreached OK outputsignal

Controling the FY

Put the switch in the set-up position Push a button for left or right till the wanted position is reached. Push save to save the position in the Pic's memory. Push next, to go to the next position etc.etc.

Some experiance is necessary for connecting the steppermotor in the right way. Otherwise it moves to the wrong way. If the lateral speed is too high the stepperdriver can be put in the halfstep mode.

If the controller is powered on , the FY is forced to the start position and in the Pic the steppercounter is first set to the zero position and after that it moves to the last saved position.

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