Crowbarred current source with fuse model 03 PUBLIC

Same as Crowbarred current source with fuse model 02 but with Thyristor latching crowbar to allow higher current fuse to be used.

Same as Crowbarred current source with fuse model 02 but with Thyristor latching crowbar to allow higher current fuse to be used.

Once the current limit is reached, Q1 starts to turn on which then turns Q2 on in a positive feedback loop. Both transistors turn on and short the Clamped net to ground.

Note that Rlimit1 must allow enough current to flow out of C1 to actually blow the fuse. If it does not, the fuse will not blow but the Thyristor will still clamp the output until power is removed and C1 has discharged.

Beware setting Rlimit1 too low as the current from C1 may blow Q1 and Q2! A more robust but slightly slower response circuit can be made replacing Q2 with a dedicated thyristor device: retain Q1 and Rpulldown1 connecting the collector of Q1 to the thyristor gate, the thyristor cathode to ground and the anode to the Clamped net.