Questions tagged [reverse-polarity]

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Reverse voltage protection and high-side current switch

Initially I chose a Infinion PROFET smart high side switch (ITS428L2). In the datasheet it is stated that this device can provide reverse battery protection with external resistor. Frankly, I am not ...
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1answer
451 views

Reverse voltage protection using a Power MOSFET at low voltages

I don't know as much about MOSFETs as I'd like to. However, I'm planning on using a Power MOSFET to limit reverse polarity issues on a 3V coin cell, i.e. just above 2.7V. How do I pick a power MOSFET ...
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4answers
376 views

Is this protection circuit designed properly?

I designed this protection circuit to avoid reverse polarity and over-voltage. Here is the circuit: simulate this circuit – Schematic created using CircuitLab Is the circuit designed ...
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2answers
977 views

Why is there a resistor in this reverse-polarity-protection circuit?

I was looking at the recommended reference implementation for a particular integrated circuit (the TI SN65HVS880, data sheet here). It runs off of a 24 volt power supply. The circuit diagram looks ...
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2answers
846 views

Do DC/DC converters provide reverse polarity protection?

I plan on using a TPS63061 as DC/DC to get a steady 5V from 4xAA batteries. The data sheet says: 8.3.4 Undervoltage Lockout An undervoltage lockout function prevents device start-up if the ...
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2answers
1k views

Motor Speed Controller Causing Relay to Lose Voltage and Stop Working

I'm having some trouble wiring up a camera slider where a motor moves the camera to one end of a slider and hits an NC/NO/C 3-pin switch which triggers a 12V 8-Pin DPDT relay to reverse the motor ...
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2answers
263 views

How can the reverse voltage of an LED decrease?

I recently build an LED matrix (for LED cube) and when testing I discovered that multiple other LEDs turned on when I triggered a specific one. Upon measuring I found out that several LEDs were "...
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2answers
69 views

Reverse of referencing everything from ground

Say we live in a world where p-type carriers just have more mobility and therefore switches faster than n-types, so we'll favour PNP's and PMOS's. So in such circuits, we reference everything from the ...
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1answer
377 views

Minimal reverse voltage protection

I'm designing a battery-powered circuit in which a power MOSFET, controlled by an ATtiny85 MCU, switches a resistive load (very, very low frequency). The battery is Li-Ion, fully charged at 4.2V. ...
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1answer
614 views

Multiple power input + Reverse polarity protection

I have the following power sources: AC/DC adapter (5V-36V) 5V USB I connected the two power inputs properly (diode) but I am not sure about the reverse polarity protection. I haven't found any ...
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1answer
2k views

I am building a simple reverse-polarity circuit using two relays. Will it create an endless loop?

I am planning on using the following circuit for my motorized value. But I'm bit skeptical about how this might continue to work. Although I'll be using two identical relays, my fear is that at one ...
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1answer
406 views

Adding reverse polarity protection to battery discharge circuit

I'll open with a caveat - I have zero training in the field but I do like tinkering. I'll try to make my question as specific as possible but do forgive if info is missing at this stage! First of all,...
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1answer
763 views

MOSFET gate protection zener diode math .please help

My circuit's voltage input can range from 6V to 12.6V. I want to use a p-ch mosfet for reverse bias protection. However, the FET I want to use has a maximum VGS of +/- 8V, so I have to protect it in ...
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3answers
751 views

How can I prevent reverse voltage in my stop/tail light design?

I'm looking to modify the rear lights on my 72 VW beetle to enhance ascetics and improve safety. I intend to use LEDs to achieve this and feel that both the indicators and reverse lights should be ...
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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 ...
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2answers
2k views

Reverse polarity protection using MOSFET - what is the voltage drop after it?

I am using this schematic for reverse polarity protection of an IC (bq78412). However the same IC has an ADC that senses the source voltage and appears not to be tolerant to reverse voltage either. ...
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3answers
6k 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 apply for a short time? For ...
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1answer
2k views

Why do the 2N2222 and PN2222 avalanche differently?

I've been experimenting with a 2N2222 transistor (in the TO-18 metal case) and using it as an avalanche transistor -- by not connecting the base and having the emitter and collector connected in ...
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1answer
261 views

H-Bridge Power Supply Erratic Behavior

Description: I have built a copper plating tank to plate circuit boards and am using a technique called Reverse Pulse Current plating to help aide in the copper plating process. What that involves is ...
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3answers
6k views

Reversing polarity of motor with timer

I have a timer that allows me to preset times and run a motor for a predetermined amount of seconds. I need this to reverse polarity as soon as this predetermined time has expired. The timer is a ...
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1answer
931 views

Circuit with reversing polarity and two microswitches

I am building a time-lapse camera slider with the following components 2rpm DC gearbox motor PWM with reversible DPDT switch to reverse motor 2 SPST Microswitches I am trying to wire the ...
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2answers
4k views

Reverse current protection for a battery-operated circuit

I'm planning a hobby project with the following characteristics 3.3 V circuit, battery operated (by regulating standard AAA batteries) Most of the time in "sleep" mode, so I need a very small ...
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3answers
63k 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 ...
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1answer
262 views

Controlling direction of current flow through pin depending on the type of device connected

I have a small portable device - lets call it MASTER - which can be inserted into two different accessories - CHARGER and SLAVE. You can check very rough block diagrams in the attached picture. ...
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2answers
3k 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 ...
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1answer
2k views

Input protection circuit with P MOSFETs and SPDT for ON-OFF switch

I am making a circuit which may draw up to 3-4 Amps, so I am avoiding using a Schottky diode as fool-proofing it from incorrect polarity on the battery (12V, automotive style) input. I have used P ...
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2answers
19k views

limit switches to control motor direction

I am trying to use two limit switches and two DPDT relays to control the direction of the motor. When the power is applied the motor should rotate one direction (direction for this question isn't ...
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3answers
16k views

How does USB Type C handle reverse polarity

The new USB Type C connector doesn't have a physical reverse polarity protection anymore. You can plug it in any way you want on both ends, there is also no A and B end anymore, it's all the same. So ...
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2answers
541 views

Battery Polarity

I was bored at work, and remember when i was little, putting batteries in the wrong way would stop the object from functioning, then decided to try reversing the polarity of the batteries in my torch, ...
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1answer
362 views

How to measure the negative voltage on the ADC with only positive voltage reference available?

I have a Phocos CA-08 controller where I wanted to measure a solar cell and a battery voltage with the MCU. The first thing I made was to connect grounds of CA-08 (solar and batt sockets) to MCU ...
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2answers
1k views

Why don't solar cells produce visible light when supplied with electricity?

... A cursory Google search didn't reveal an answer... Is the energy conversion a one-way process?
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1answer
2k views

Are Supercapacitors Polarized

There seems to be conflicting information on the internet. Are super capacitors polarized? For instance, could you charge them and then suddenly invert their polarity (à la charge pump)?
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3answers
7k views

Rapidly reverse polarity of electromagnet

Please forgive my zero knowledge of electronics. I have asked my people what I thought was a simple question but I just get bogged down with endless questions which I can't answer. Expressing the ...
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3answers
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Reverse Voltage Protection with a P-channel MOSFET [duplicate]

I'm looking to use the P-channel MOSFET approach to reverse polarity protection as described here and here (fig 5). Basically this picture: I've seen that circuit topology used, for example, here, ...