Today, I have completed the internal case wiring, and added the 5V 1A regulator.
Due to the small size and tight tolerances of some parts in this, some of the wiring was a little tricky. The RG-174 coax connecting the RF output up twisted at the board end, and had to be stripped back and redone to relieve the torsion. The 1A 5V regulator is a very simple 7805 based circuit mounted on a small piece of prototyping board atop two self adhesive stand-offs. I found that the bare 7805 ran excessively hot (too hot to keep a finger on for more than a few seconds) so added a heatsink. I also took the time to mark the board with the bands for each LPF, so I can see whats in what slot. Later I will make up a little 'Band Card' to attach to the outside of the case showing this.
As well as the coax, another connection that caused problems was to the 'Edit' button. On testing, it turned out that in the confusion of working on things upside down and back to front, I had wired the buttons up arse about, so had to dismantle and swap the connections over. In doing so, the terminal came out of the damn socket! After refitting this, I then couldnt get the sleeving over the pin!
But, with those issues corrected, it is now working in its nice case. Before putting the lid on, I will measure the remaining space, to see how practical it is to fit a battery pack for truly portable operation. I still need to find a suitable plastic housing for the GPS module.
No comments:
Post a Comment