HP97 The journey begins
|
05-04-2019, 11:48 AM
Post: #76
|
|||
|
|||
RE: HP97 The journey begins
(05-04-2019 09:16 AM)Harald Wrote: Hi Tony, Ok thanks. As the coil is paid for and on its way, I'll try anyway, you never know. The PSU is based on the standard boost circuit for a common MC34063 chip as per the data sheet. Circuit attached. It provides 6.2V and 5V via a LDO regulator for the processor. The PCB is pretty tight for real estate but I routed all supply lines in heavy trace and is well bypassed. It is hard to have a common GND point but of course I'm no expert and a multilayer board is about 4 times the cost. I'll try to put some PCB details together tomorrow. I thought about, and prefer, the simpler voltage doubler but not sure if the reader chip expects a more regulated supply as I don' have access to the operating specs for it and the display drivers. I'd like them to all work happily at 5.5V but again, not sure over a wide range of calculators. cheers Tony |
|||
« Next Oldest | Next Newest »
|
User(s) browsing this thread: 3 Guest(s)