APRS Tracker: Enclosure
Up until now the APRS Tracker has been assembled on a breadboard in a rather large enclosure (see below). While convenient it is not very practical. So . . . lets put this into a small box:
Using a blowup of the RS PCB that would fit into the box, layout where everything will go / fit. This will take a bit of work to get the blowup to represent the actual board but will save time and perhaps your box when you start toe cut. Part of my blowup diagram can be seen under the box in the Fig 1.
(Fig 1) Once you have the layout finalized it is time to make some holes. A ‘Dremel’ tool with various bits will be a big help. Talk you time, Here are the parts placement and cuts:
- Upper right: The black cube is the RJ-45 jack on the SparkFun PCB, tucked under the PCB. It will be glued to the Main PCB with the connections coming up through the PCB holes.
- To the left is the USB Micro-B SparkFun PCB. This too will be glued to the Main PCB with some glue added around the actual connector for added strength.
- On the left side is the GPS Receiver with the antenna cut through the box. While the antenna should face up it can be inside the box. It does look cool sticking out and will get protected with clear tape when finalized.
- On the bottom is the push button rotary switch.
Add components (Fig. 2)
- A 10 position stackable header has been added to accept the
TFT Display pins. The height was adjuste with a small spacer at the bttom of the header. This puts the display at a good height to clear the RJ-45 jack and the transformers (still to come)
- 10 wires have been added to the header, the display only needs 9, to allow some flexibility in placing the display. This will be finalized before solder and the extra lead cut off one end or the other.
- Two screws were added to hold the board in the box.
- The RJ-45 jack on its Sparkfun PCB has been epoxied to the board.
- The GPS unit is a tight fit at the top of the board behind the stackable header.
Now fit in the transformers etc.
Using the enlarged layout, visible below the W2DEN APRS Tracker carefully layout where the components will go. This will take some trial and error to fit everything into the case.
- The two transformers and output voltage divider were fit in first.
- The output is just above the RJ-45 connector, the input in the upper left.
- The output voltage divider and by-pass cap are squeezed between the transformer and the RJ-45 Jack.
- The input by-pass cap is soldered below the board.
- The PTT socket fits nicely between the transformers.
- The TFT Display 2N222A is wired directly to the D3 Teensy pin in the upper right.
- Be sure to leave room for the rotary switch just to the left of the 2N222A.
- The Tennsy is then fit with the USB wires feeding out the bottom.
- They are soldered to the SparkFun USB Board (red, bottom center) which is then epoxied to the board. BE CAREFUL fitting it through the hole in the case.
- Now wire the TFT stackable header to the Teensy.
- Decide which 9 pins you want to use on the TFT Display Header and melt the unused on and cut off the wire.
- Point to point is fine.
- Create and follow a diagram.
- Check you work with a pin header in the TFT header, then an ohm meter to confirm eac TFT header pin is correct.
- Solder everything…
- For the first pass just solder the Teensy Pins that are needed:
- TFT Header, Output transformer
- Two unused RJ-45 wires are coiled and left in the lower left corner, just in case we need them later.
- Plug in the TFT Display
- Plug in the USB cable
- The screen should light up and display:
Tracker Loading …
This is the final step. Wire the last components and put it into the box.
- The pins were removed from the GPS and replaced with 4 stranded wires (from an old USB cable).
- The wires were then soldered to the board.
- Rotary PB Switch:
- the two grounds were connected at the switch.
- The 4 connections were attached to the board using stranded wire, same as the GPS.
- Place the board into the box and screw it down.
- Insert the GPS module. A spot of glue or double backed tape may be needed, depends on how tight the fit is.
- Insert the switch and secure it with the nut.
- NOTE: the switch connections hit one of the display On/Off resistors. It is covered with a piece of wire insulation to prevent a short. (the white end of the insulation is visible to the left of the switch.)
- Insert the 4N25 into the socket if you have not already done so.
YAHOO! You are done.
Plug in the USB cable and the tracker should light up and in a few moments connect to enough sats to show you the screen
Prototype Breadboard Enclosure:
Here is is the interior of the prototype in the RS box with the circuit on a breadboard.
The Teensy USB is hardwired due to the USB being broken from the board. Details are here: Link
The White connector to the right is the RJ-45 radio I/O.
The GPS is on the left wall of the box.
Above the Teensy is the 1:1 transformer and PTT optical isolator.
The breadboard is double sided taped to the box.
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