Questions tagged [reverse-polarity]

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2
votes
3answers
3k views

How to find Voltage based on reference nodes?

I came across this problem and I'm trying to really understand it. VB is the voltage drop across a particular element, it is the change in voltage from node a to node b. Find the value of VB in ...
15
votes
3answers
9k views

Does an electrolytic capacitor degrade each time it receives reverse voltage?

I know that I mustn't connect an electrolytic capacitor reversely. It will explode if I apply the reverse voltage long enough. But, what happens if the reverse voltage is applied for a short time? ...
17
votes
3answers
4k views

Do serially connected diodes share equal reverse voltage?

If I place three cheap 200 V rated diodes across a 500 V supply instead of one expensive diode, is the system guarantied to work correctly? My worry is the situation at which two of the diodes share ...
0
votes
1answer
193 views

How does this BJT affect the circuit? If it does, how should I simulate on Circuitlab to see the effect?

I am trying to understand how NPN Q23 in the picture below affects the operation of the left circuit. If it doesn't then what we get is the circuit on the right with the only transistor now being Q30....
2
votes
2answers
1k views

Reverse-polarity protection P-channel MOSFET

There are many ways one can build a reverse-polarity protection circuit. Using diodes, Shottky diodes, n-MOS in the return path and using a P-channel MOSFET on the positive side of the circuit. My ...
1
vote
2answers
113 views

A DC source and only a Reverse Diode

What will happen having only a DC source and a diode connected in reverse? Will the diode or the source overheat over time or something bad might happen if you let it operate like that?
4
votes
6answers
10k views

maximum reverse voltage applied to a resistor-LED configuration

Consider the simple circuit below: simulate this circuit – Schematic created using CircuitLab LED datasheet: link Does the applying of a reversed 36 volts to this circuit damage the LED? ...
3
votes
3answers
69k views

Change Direction of 12v DC Motor Rotation using Relay

I want to make a circuit to change 12 Volt DC Motor direction and move some thing between two points. Using Relay or some basic limit switches.Like this Image. I got a Circuit As i want... AUTOMATIC ...
3
votes
4answers
2k views

How to avoid voltage drop when using full bridge rectifier as reverse polarity protection

I found a couple of old bridge rectifiers. After reading some docs and tutorials about reverse polarity protection decided to give them a try. The problem is nobody offered a solution against the ...
0
votes
4answers
2k views

How to detect reverse-polarity post-mortem?

Original - Apr. 13, 2015 There are many questions here about preventing reverse-polarity, most of them ending up with a series FET that is driven by the opposite supply rail: (shamelessly stolen ...
4
votes
1answer
888 views

Overvoltage and reverse polarity protection

There are two well-known circuits well described in the Internet, including this site: Reverse polarity protection with P-channel MOSFET; Overvoltage protection with SCR and Zener (so-called "...
4
votes
3answers
13k views

Why reverse polarity causes damage

Is it because it can exceed the reverse breakdown voltage of semiconductors? For instance in low voltage devices say 1-5v is the reverse voltage rated a lot lower than that for damage to occur? Also ...
0
votes
1answer
108 views

How to wire a PPTC polyswitch + blown indicator LED to protect a bi-directional DC motor from stalling?

I have the following setup and it works well as is, except that I would like to protect the 12V DC motors (Reverse High Torque Permanent Magnet 12V DC motor) with a PPTC polyswitch + a LED to indicate ...