Using MAX641 integrated circuit, manufactured by Maxim IC, can be designed a very simple step-up converter using few electronic components. This step-up high voltage converter electronic projects allows a maximum output current up to 1A. Low battery voltage detector input compare LB1 with internal reference of 1. 31 V. LBO output goes in low state
when the voltage at pin 1 falls below 1. 31 V. The threshold voltage for "low battery", is determined by voltage divider R1-R2.