Sometimes the designers use the resettable fuses instead (thermal or PTC) or breakers, so that the user won’t have to replace the fuse. So the circuit is saved and you just need to replace the fuse. In return this shorts the supply and so there will be a large current that blows the fuse. The thought behind it is that if somebody connects the supply backwards, the diode will be forward biased and clamps the voltage across the circuit to a small negative value, like -0.7V to -1V, and that should be enough to save the circuit. I have seen this in some designs before and is a dirty way of doing reverse polarity protection. The diode is a general purpose power diode. The fuse is made of 2x 25A fuses in parallel. And the solution is so simple too.īelow is the circuit they had in their design. I mean what the hell man! In any product where they leave it to the user to connect the power lines, they MUST make sure that their device can withstand a reverse polarity connection! Isn’t that obvious?! I mean probably they get half of their products returned because some dude like me connects it backwards. I thought maybe I connected it backwards, and being so sure that an inverter design must have adequate reverse polarity protection, I connected it backwards and it blew up!!!! DAAAAMMNNN! Unfortunately it was too high and my inverter started complaining. I asked the host for a drill battery and he had an 18V one. At the end of the party I realized I had an inverter in my car. They are always plugged in, so always keep their battery charged and when the power fails they automatically power on and keep things on.īut hey! you may get surprised by an outage outside home like happened to me. Well I guess the UPS (Uninterruptable Power Supply) devices are not super expensive nowadays, and if you live somewhere that power outage is common, I really recommend you get one.
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