Hi Jules, Still interested to find out about powering the Melcor SC-635? I got one and succeeded to power it from 2.2 to 3.0V There is a switching regulator on the PCB (AS1930 from Astec International) that generates negative voltages (as referred to the negative side of the battery: -12.4V , -4.8V , and -2.0V At 2.4V, the current drain varies from 71mA (idle mode) to 185mA (all LED segments lit). For some strange reason, this current rises to 211mA when the C/CE key is pressed I will design a substitute power supply based on a single Li-ion battery with step-down regulator to deliver 2.4V Best regards Francois