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Chapter 2a Page 9
Utility Power Supply
This power supply can provide a localized DC voltage source from the DCC track supply. Designed to be used for low current accessories such as crossing lights that do not need a lot of current and where running a special cable from a remote DC supply may be too complicated.
copper strip and 1 is now the bottom left corner. Double check the position and twist a #31 (1/8 inch) drill in the marked holes to remove the copper. Clean up the wisps with a knife and check with a meter that there is no electrical circuit across the hole. Some of the component leads are larger than the PCB holes and a #56 (1.12mm) drill will be needed to enlarge the hole. Solder in the wire cross links. Use solid single strand insulated wire. "Cat 5" communications cable can be used for these link wires. Solder them in and cut off excess. Insert the resistors and diodes. Double check the positions and polarity before soldering them in. Follow them by the larger components, again checking the polarity of the capacitors. The legs of the bridge rectifier can be bent to fit it close to the board or just push it down as far as it will go and solder. Check the copper side that no solder is bridging between the copper strips. Running a craft knife blade down the insulation between copper strips will usually find solder bridges.
Construction: Cut the strip board 18 holes wide by 6 rows deep. If you want to allow mounting holes or input/output terminals expand the size to suit. It helps to put masking tape over the extra unused holes. Mark the position of hole number 1 on each side to help alignment then mark the position of the copper cuts (X on diagram) note the board has been flipped vertically to show the
Select the correct resistors (R1 & R2) from the chart to give the voltage that you need it can be 3, 5, 6, 9 or 12 volts. To get the best voltage range the resistors must be 1% tolerance or selected with an Ohm Meter. With these the voltage variation will be less than 2% on most voltages. Install terminals or wires as required and test.
