Russian RPN calculator series Elektronika MK

[jebem]

(05-29-2019 05:03 PM)John Keith Wrote:  

(05-29-2019 02:49 AM)toml_12953 Wrote:  ... The manual specifically warns against using rechargeable batteries.

NiMH cells are lower in voltage than alkaline cells so it is very unlikely that they will damage the calculator. The worst that can happen would be erratic operation, dim display etc.

Surely the machine switching regulated power supply can cope with a large input voltage variation, as long as it is in good shape (electrolytic caps failure rate is high here).

Also the lower internal impedance of modern rechargeable cells compensates for its lower nominal voltage supply, when compared to 1.5V non-rechargeable cells, specially for the lower quality ones, that will have a higher voltage drop when supplying 100 to 200mA consumed by these calculators.

The calculator was designed to work with 4.5V nominal input voltage, coming from one of two power sources:
1. Three 1.5V non-rechargeable cells (little smaller than standard AA batteries) commonly found in the Eastern Countries in the USSR era, to give the machine portability while traveling around;
2. An alternative Elektronika D2-10m AC kind of regulated power adapter to use as a desktop machine. In this case the batteries should be removed.

Probably people would think that the power adapter was a charger but that is not the case.
Hence the note in the documentation.
Just my 2 cents of Euro.