I'm having fun with fixtures these days. This one is a variant of the programming fixture I've shown last week:
http://downloads.qi-hardware.com/people/werner/anelok/tmp/mk3-quick/quick-pwr-top.jpg http://downloads.qi-hardware.com/people/werner/anelok/tmp/mk3-quick/quick-pwr-bottom.jpg It only has pins for battery and USB power. By omitting all the other contacts, most of the "floor" of the fixture can be left open, giving access to the circuit there: http://downloads.qi-hardware.com/people/werner/anelok/tmp/mk3-quick/quick-pwr-loaded.jpg I used this to measure the performance of the boost converter. The power supply circuit has changed considerably since the CR2032 days, in part because we now have to operate with a much lower battery voltage (and thus higher current), and also to avoid power drops when handing over between USB and battery [1]. The results of the first round of testing will be in my next post. The above picture also shows a new addition to the fixture: so far it consisted of the frame that holds the PCB and that contains the holes for the pogo pins, and a stand that goes below it, providing clearance from the table and holding the connector. There is now a third element: a clamp that snaps onto the frame and presses down on the circuit: http://downloads.qi-hardware.com/people/werner/anelok/tmp/mk3-quick/quick-clamp.jpg It's admittedly not the prettiest piece of engineering but it does the job so far. And if it breaks, it's easy to print a new one :-) The design of the power-only fixture is here: https://gitlab.com/anelok/mexp/blob/master/quick/quick-pwr.slvs It also has its own design for the base, which adjusts size and placement of the opening for the connector: https://gitlab.com/anelok/mexp/blob/master/quick/quick-pwr-base.slvs And this is the design for the clamp: https://gitlab.com/anelok/mexp/blob/master/quick/quick-clamp.slvs - Werner [1] Section "The USB plug - a hidden killer" in http://lists.en.qi-hardware.com/pipermail/discussion/2015-April/010843.html _______________________________________________ Qi Hardware Discussion List Mail to list (members only): [email protected] Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion
