04-06-2019, 03:46 PM
Cheers for that 
Q705 used as a switch to preserve S802's integrity makes sense to me, the time constant of the components in Q704's base circuit being long enough to turn on Q705 long enough to prevent the formation of an arc when S802's common and NO contacts break open but short enough to enable a decent charge to be retained by C801 in order to supply the auto shut off solenoid.
Lawrence.
Q705 used as a switch to preserve S802's integrity makes sense to me, the time constant of the components in Q704's base circuit being long enough to turn on Q705 long enough to prevent the formation of an arc when S802's common and NO contacts break open but short enough to enable a decent charge to be retained by C801 in order to supply the auto shut off solenoid.Lawrence.
