HP97 The journey begins

[teenix]

(02-06-2020 01:44 AM)Helix Wrote:  Thanks!
I still have a couple of questions.
The help file says not to exceed 4.5V battery voltage.
Does that mean that fresh alkaline batteries should be avoided?
I suppose that standard AAA NiMH batteries, recharged on an independent charger, are safe.

Out of curiosity, is the power consumption of this CPU board different from the original board?

3.6-5.0V is ok for all CPU boards. There are voltage regulators after the battery voltage boost circuitry that will keep the original card reader/display circuitry at their original voltages. 4.5 was an arbitrary safe value.

The original 67 was not supposed to be used while the charger is on without batteries, so I would suggest not using the modules while battery charging, unless the charger voltage that feeds the calculator circuitry is <= 5V.

With 0.00 showing on the display and 4V battery...

Current for the 65 is 138mA (orig) vs 84mA
The 67 is 165mA (orig) vs 65mA.
The 55 new is 76mA with PIC oscillator driving the anode driver

Active Bluetooth will add about 8mA.

cheers

Tony