GPS Clock Built

Just a quick post… gps_clock_2_8900Yesterday I wrapped up the schematic and printed circuit board (PCB) design for the GPS clock, and built it. One software change was needed — in the course of laying out the pushbuttons, it worked better use to them in a different order (e.g., up was formerly button 1, it became #4). Thankfully that soft of change is trivially easy to make in software. Of course I built the board with a 6-pin AVR programming header to enable software changes. Continue reading GPS Clock Built

MAX7219 CWG 8-digit LED Display

In anticipation of the 2015 Leap-secondBP_LED_23_59_60_9049, I’m in the process of constructing a monitor for my Trimble Thunderbolt GPS clock and DO so I can watch it “live”. For the clock display, I’m evaluating an inexpensive¬† 8-digit LED display with an SPI (mostly) interface from a MAX7219 (bought on-line for $2.35).

For a quick and easy test, a Bus Pirate is just the trick. Continue reading MAX7219 CWG 8-digit LED Display

Calibrating an HP 5315A Universal Counter

Today I calibrated5315A_adjust_bench_8873 my recently purchased Hewlett Packard 5315A Universal Counter, the portable sibling of HP’s 5316B bench counter. My unit is in very nice shape and has option C to go to 1GHz, and the option 4 ovenized oscillator — this is particularly important as this portable unit has no external 10MHz reference input. (Though I may construct one.) Continue reading Calibrating an HP 5315A Universal Counter