Questions tagged [reverse-polarity]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
-1
votes
1answer
579 views

protection circuits [closed]

I was wondering if anyone could help explain how these work? I know they are missing information, but I wanted a general idea on how they are meant to function. Why place two diodes facing each ...
1
vote
2answers
1k views

Sizing protection diodes

In designing basic upfront protection in a circuit, I've encountered a strange conundrum. I find it's very difficult to size both a reverse voltage protection diode, and a transient voltage diode (...
2
votes
1answer
3k views

Voltage Divider to protect P-FET gate on a Polarity Inversion Circuit

I'm trying to implement a polarity protection using the P-MOSFET technique on a 30v DC circuit How can I protect the gate of a IRF9540N (Vgs 20v)? I saw that I can use a voltage divider using 2 ...
0
votes
1answer
115 views

Circuit with reverse polarity data lines

let`s say I have 2 Microcontrollers and I want to connect them to send data between them. I have one dataline and GND (datarate or how to sync is not part of this question). Is there a possibility ...
2
votes
2answers
2k views

Reverse characteristics of power MOSFET

So, I'm designing a reverse battery protection circuit using a MOSFET, following this TI application note. I tested it, it works great, Rds(on) is low as expected. However, I'm not really comfortable ...
0
votes
1answer
327 views

Reverse polarity protecion on an electronic load

I want to add reverse polarity protection on my electronic load which will be capable of sinking 20A and with a max. voltage of 50V (max. power is limited to 250W). Because I want to go with low input ...
0
votes
1answer
324 views

Wiring Motor to DPDT Polarity Switch

I am trying to wire my motor (US Motors, Model: C55JXKNL-5041) to a polarity reverse switch. The diagram printed on the motor is as follows: BLU ____L1 BRN ____INS BLK ____INS ORG _^ WHT _^ YEL ____L2 ...
1
vote
1answer
951 views

Can a DMM continuity probe fry an IC?

I just finished soldering a QFN package to a breakout board, and was about to go at it with my multimeter in continuity testing mode to check for bridges, when it occurred to me that some ...
4
votes
6answers
9k 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? ...
1
vote
2answers
767 views

Charlieplexing 7-segment display segments vs segment

I understand the principle of charlieplex and the use of tri-state. What I don't understand is, can I light all segments on a display at once or do I have to light one segment at a time? Say I have 8 ...
0
votes
4answers
5k views

Put 1 of 3 batteries the “wrong way” to prevent accidental turning on? [closed]

My headlamp accidentally turns on inside my backpack. If it used two batteries, I would put one the "wrong way" to prevent it from coming on. However, my lamp uses THREE AAA-type batteries. Can I ...
1
vote
1answer
393 views

Output of 4.8V due to reverse polarity series schottky diode?

I was reading through the Data Sheet for the Photon, an IoT dev board: https://docs.particle.io/datasheets/photon-datasheet/ and under the Power section it says: When the Photon is powered via the ...
3
votes
2answers
737 views

Dual rail reverse voltage protection

After watching Afrotechmod's tutorial about reverse voltage protection, I wondered if I could incorporate it in a circuit I'm working on. Unlike the circuit in the video, mine's dual supply, and there'...
0
votes
1answer
102 views

LDO outputting low voltage. LDO or auxiliary components fault?

I burned a circuit by applying reversed polarity voltage. I measured the LDO that is supplied with 5 V and should output 3.3 V, however it only outputs ~2 V. Now what can I deduce from ...
2
votes
3answers
2k views

Reverse polarity protection for a very low voltage devce

I want to add reverse polarity protection to a device which is powered by a single AA battery, so its voltage might go down to 0.8 V. Forward diode is too huge of a drop. I've already thought about ...
0
votes
2answers
2k views

Reverse Polarity & Load Dump Protection (TVS)

Based on this and other material I’ve read, I should have a diode for reverse polarity protection and a TVS for load-dump protection in an automotive circuit. I have prototyped the circuit and its ...
1
vote
3answers
1k views

What circuit will allow reverse polarity and continue to work?

I am looking for a circuit that will power my device with 12-24v no matter the polarity, the device will use around 1a maximum. I know a bridge rectifier should work but I cannot deal with the ...
-1
votes
1answer
372 views

Reverse Current in N Channel Power Mosfet

I am designing a bidirectional current source to drive a large (~60A) current through a large inductive load (100's mH) and facilitate very fast switching times (as close to an 1A/us as possible). My ...
4
votes
3answers
12k 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 ...
2
votes
1answer
435 views

Optocoupler in reverse-active mode

I was recently reminded that BJTs can be used in reverse active mode. Can somebody enlighten me whether and to what extent the same is true for optocouplers? Do the same limitations apply to reverse ...
1
vote
1answer
1k views

About 18650 batteries possible accidents with reversed polarity

We all know that lithium batteries are dangerous and can blow up if we use them the wrong way. My doubt is, if I accidentally place them in the following sequence in series (Pay attention to the ...
0
votes
1answer
297 views

Reverse Polarity Protection: Is this method safe!

Consider the above circuit. The N-channel MOSFET has been used as a low side switch to provide reverse polarity protection. A capacitor charges to the 12V supply(battery) voltage and subsequently the ...
1
vote
1answer
81 views

Reversing Polarity on Switch Mode PSU to use on Audio Equipment

I have a normal 12v 1amp switch mode psu. with positive pin, negative sleeve. I want to use it on a Roland ex3 s keyboard, which I got as a gift, but no power supply. The PSU specs match those of the ...
0
votes
1answer
396 views

Reverse voltage protection diode - necessary?

I'm designing a system to drive 5 strips of RGB LEDs, it will draw around 25 amps, at 12 volts. This system is only going to be used by me, and I have the suitable power supply coming in the mail. ...
2
votes
3answers
5k views

Is it possible to use a MOSFET for Li-ion reverse polarity protection when protecting a charger?

I've made a simple charger out of 4 TP4056 modules and 4 18650 sockets. These modules have overcharge, undercharge and overcurrent protection included, but I also want to know how simple it would be ...
1
vote
2answers
2k views

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 ...
1
vote
1answer
527 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 ...
4
votes
4answers
433 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 ...
2
votes
2answers
1k 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 ...
3
votes
2answers
1k 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 ...
2
votes
2answers
2k 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 ...
4
votes
2answers
377 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 "...
0
votes
2answers
71 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 ...
3
votes
1answer
471 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. ...
1
vote
1answer
762 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 ...
1
vote
1answer
4k 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 ...
-2
votes
1answer
522 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,...
0
votes
1answer
873 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 ...
-1
votes
3answers
968 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 ...
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 ...
3
votes
2answers
3k 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. ...
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? ...
4
votes
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 ...
2
votes
1answer
290 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 ...
-1
votes
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 ...
1
vote
1answer
1k 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 ...
1
vote
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 ...
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 ...
2
votes
1answer
289 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. ...
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 ...