This is a first edition SCR crowbar model ckt.
Plans to add better circuit breaker model for SCR using differential op amp ckt that will trigger a 0v pulse within fractions of a second at the BE junction.
This is a pretty good example of how an SCR works and when to use one.
Toggle the switch for overvoltages and watch the crowbar work its magic. Stop conduction on the SCR using the NC switch. Note that this will not reset the SCR device unless power supply is switched to 9.7V at the time of the reset. This is because current must cease or fall below holding values for the SCR to stop conducting. Even when the supply is toggled the SCR continues conducting until normal voltage conditions resume AND immediately followed is a break in current flow through the SCR. Until overvoltages occur again the SCR will not be able to conduct.
