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1 vote

Interrupt rating of all fuses in branches of same circuit

Thanks to @mkeith's comments, I think I came up with a workable solution. The idea is simply to 'stage' the fuses and make their rating to IR domain overlap so that in case a low-current / low-IR fuse ...
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1 vote

Turning PNP fully off for fuse indicator

The function of the transistor in such a circuit is to reduce the current consumtion while the fuse is intact. A small current flows all the time and only with a blown fuse the LED current is drawn. ...
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0 votes

Turning PNP fully off for fuse indicator

From my point of view, I would change a little the "circuit". Something as this. If diode current too "high", you can change 27k -> 47k ...
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0 votes

Amp reading on multimeter significantly varies depending on port

You didn't post a link to your multimeter user manual so I'm assuming it's a 199.9 meter type. The meter module is full scale at 200.0 mV. That means that the shunt resistor value for each range is as ...
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  • 160k
1 vote

Interrupt rating of all fuses in branches of same circuit

You absolutely can't make it work at 12V without going to ridiculous costs. Just the wiring would cost a fortune. One way to do it is to have a 144V pack (48V * 3), and connect normal AC electronic ...
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3 votes

Amp reading on multimeter significantly varies depending on port

A single solar cell only generates about 0.5 V (as your rating indicates). Many DMMs have a significant resistance in some of the current ranges -- needing 100-500 mV or higher voltage drop across the ...
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2 votes

Interrupt rating of all fuses in branches of same circuit

Borrow a trick from AC mains The power company is required to ensure that the supply to your house is incapable of exceeding 10,000 amps (or where needed, 22,000 amps). And then, the main breaker is ...
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2 votes

finding replacement for resistor labeled as fuse in schematic

It's labeled as F because it's a fusible resistor. The schematic gives the resistance as 3.5R I think due to the amount pixels missing.
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3 votes
Accepted

finding replacement for resistor labeled as fuse in schematic

Pick a fusible "safety" resistor of the same value (3.3\$\Omega\$) and tolerance (5%), and a similar physical size. It looks like a metal oxide film type. There are also wirewound types. ...
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3 votes
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Using fuse during initial tests?

Does the fuse protect the circuit from these failures (...?) Would the fuse protect the switching element? Probably not - this is consistent with my experiences as well. do you recommend continuing ...
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5 votes

Using fuse during initial tests?

Why would you ever not use a fuse? It's basic protection. Sometimes a tungsten filament bulb or several in parallel (in series with the fuse) can help during early testing. It has relatively low ...
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0 votes

How to choose the correct fuse in a double paralled battery supply system?

There's something odd about your design there. Fuses are selected by current rating, not resistance. If you put 200A through a 200m ohm fuse, it will be dissipating 8kW, which makes no sense. Fuses ...
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2 votes

Why do Americans use fuses and not differentials and breakers like Europeans do?

Not directly relevant, but I'd like to address the fallacy that breakers are inherently safer. Which I also used to believe was true until I spent some time studying how domestic electrical systems ...
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  • 21
0 votes

Electrical current fuse utilizing two PNP transistors not working

The DC gain of your upper, main path PNP is less than you expected. The output voltage drops before the trip point at the shunt resistor is reached. This can invoke enough base current in the lower ...
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  • 1,954
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Electrical current fuse utilizing two PNP transistors not working

This kind of circuit is a "bit" complicated to analyse. Here is what I found with the original picture and values, after choosing BJT. As you can see, max current is not what one expect ... ...
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2 votes

What conditions can cause a PCB fuse to fail and act as a resistor?

Pulses with low duty factor will erode filament faster than the temperature rise thus non-fusing resistance and more inductive in nH so dI/dt also causes fatigue and reduction in wire diameter with ...
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