Which means, my hypothesised setup is inferior compared to a fuse, and is far more expensive to implement.indianajo said:Mechanical breakers trip in halves of seconds. Fuses blow in tenths of seconds. Semiconductors burn their 35 ga bond wires in thousandths of a second. As you said, the rail caps and transformer have joules of energy stored up to blast current through any stressed semiconductors.
So, from a protection perspective, suddenly turning off mains power to an amplifier in the event of a fault, was shown experimentally to provide little or no protection at all.You're whistling in the dark, trying experiment that were proved total failures in the 1970's
I searched for quick blow SMD fuses with high current ratings like 10A and found they exist. The reason for choosing SMD, is because space is limited and using connecting wires to fuse carriers, would impact negatively the amplifier's performance. A narrow cut in the rails tracks should be enough.JonSnell Electronic said:Most manufacturers use anti surge fuses in the mains supply and fast blow for HT supplies after the main smoothing. This protects the output transistors/power output stage
I would like to know whether ready made 0.5A to 5A presettable circuit breakers exist. The circuit breaker is required to trip immediately when a preset current limit is reached.
In my scheme if an output transistor lets current out the base line, the zener clamp conducts in nanoseconds, keeping high voltage off driver emitters. Max zener current is 487 ma; hopefully the die shorts across and blows the 5 a fuse before the bond wire goes. Cost about $.40/channel and required no circuit board mods.Fuses protect wiring, to protect the sand you need something very much faster.
... ... ... Datasheets for quick blow fuses ... 10ms. This may be a long time for semiconductors, but it should offer protection against getting the entire power stage destroyed...