SD card adapter, no custom PCB needed.

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Joined: Thu Aug 30, 2012 6:01 pm

SD card adapter, no custom PCB needed.

Post by MN-tech » Sun Sep 02, 2012 10:24 pm

This is a no frills version of the SD card Adapter for use with the DigiLite Serializer SD Card project described by G8AJN in an earlier post. This adapter, the pushbutton described in the project documentation and a new version of the DigiLite PIC software are all you will need to enjoy transmitting files from an SD card. Thanks to G8AJN and others for providing that handy addition. The mpg file converter software works very well too.

+++ Parts:
Radio Shack part 276-148 ( breaks into two boards) or a 2” x 2” piece of 0.1” spaced perf board with pads on one side.
SD card connector - DigiKey part A101492CT-ND = TE Connectivity part 2041021-4
two 33K resistors, ( 22K to 66K according to the original design )
0.1uF cap
10 pin female single row header plug. DigiKey part 5-103961-9-ND = TE Connectivity part 5-103961-9
10 wire flat cable or loose wires if you prefer. Length is your choice, up to 12”

+++ Perf board preparation:
There is one pad which will short pin 8 and the card detect pin if not removed. Its location is pointed out on the board layout drawing. Heat it with a soldering iron and slide it off, or drill it out.
Drill clearance holes for the locator pins on the back of the SD connector. Their locations are marked in black on the drawing. One is by pin 9 and the other is by the card detect pin. The holes do not need to be an exact fit, the SD connector will be fastened by soldering the four corners of the cover.
Enlarge the holes in the outside row so the wires can pass through. This strain relief will greatly reduce the chance of wires breaking when you handle the assembly.

+++ Assembly:
Carefully position the SD connector as shown making sure pins 9 and 1 to 7 line up with the pads without any shorts between pins. The pad and pin spacings are not an exact match but it can be done. Solder the four corners of the cover/shield to the pads.
Solder pins 9 and 1 to 7 to the pads.
Solder on the resistors and the cap as shown.
Jumper pin 3, pin 6 and one corner of the cover together. 28 gauge heat strippable magnet wire was used on the assembly in the photo.
Attach the header plug to the flat cable. The connector listed is designed for automatic tooling but you can cut the pins apart and manual crimp and solder. The empty shell and loose pins costs about twice as much. You could solder the cable directly to the DigiLite instead if you don’t need the connector for programming.
Separate the wires on the other end of the cable for about 1-1/2”. Run the wires through the strain relief holes as shown. Solder and pull the slack out. You may choose to clip the unused wires.
If you want to be able to ignore a card plugged into the adapter, a switch can be added in series with the card detect pin ( marked “c” in the drawing ).

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