Under & Over cut-off with delay time circuits (around 20 seconds).
please drop any suggestion for upgrade.
To see how circuit work. Please adjust supply voltage high and low from 8 to 13 volt. (at below coner of right hand side which is use for sensing vltage)
(supply voltage at below conor of left hand side is fixed 12 volt - which is can do with 12 volt regulated ic)
If you are using 12v step-down transformer
AC operation voltage range 160 - 240v
AC 160v to 240v = DC 8.7v to 13v (on)
2 green LEDs from middle row will light on
AC 160v = DC 8.7v (under cut-off)
2 red LEDs from first and third row light on
AC 240v = DC 13v (over cut-off)
2 red LEDs from upper row will light on
delay time
1 green LED and 1 yellow LED will light on
