Vermes
Advanced Member level 4
Presented economic meter is powered from one Li-Ion cell 3,6V by a converter on system MC 34063, which raises the voltage to approximately 9,5V. Cells were removed from a disassembled laptop battery. Home made converter operates well when supplying two individual digital meters simultaneously. The converter consumes 8mA at idle. Switch on the left side of the meter disconnects the cell from the converter.
You have to remove the cell when you want to supply it.
Pictures:
Link to original thread (useful attachment) – Miernik M890G zasilany z napięcia 3.6V