Simple idea but hard to illustrate.
Volt meter can be small motor or solenoid controlled with timer (SPST switch) with a crank lever to turn round beveled shaft ( the cross looking thing at left with ring or washer so when shaft turns half way around the narrow side of bevel is up and weight (NOT logic gate) drops from shaft.
This timer weight drop device was used on heating furnace to control draft doors so home owner could get extra hour of sleep at night. A wind up alarm with supported alarm wind shaft turned beveled shaft with long side of bevel up and dropped weight rope loop when narrow side of shaft turned up.
Many electric circuit variations and uses of beveled shaft to release load can be devised.
