Questions tagged [reverse-polarity]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
30
votes
3answers
17k 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 ...
13
votes
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 ...
12
votes
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 ...
8
votes
1answer
225 views

Designing an effective power supply for embedded products

I'm currently designing several embedded microcontroller products to be powered from a wall outlet. I plan to use wall-wart power supplies to give an input of approximately 5-9V DC but I want the ...
5
votes
1answer
707 views

Replacing two LEDs with a 2-pin, bicolor LED, using a circuit that reverses polarity based on two inputs

I'm working with a commercially available circuit that can optionally be configured to disable its internal LEDs and use two external LEDs. This post discusses the use of external LEDs. One LED or the ...
5
votes
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?
4
votes
3answers
13k views

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, ...
4
votes
3answers
9k 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 ...
4
votes
4answers
379 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 ...
4
votes
2answers
628 views

High-side vs low-side reverse polarity protection

I need to make a reverse polarity and over-voltage protection for a fairly powerful device (45W @ 12V input) and after some research I noticed a weird peculiarity. A typical reverse polarity ...
4
votes
2answers
567 views

Switching power supply reverse driving protection circuit

I have already "designed" (more like followed the reference design from TI) a buck regulator based on the LM3671 (https://github.com/volium/PowerSupply_lm3671) and I've been very happy with the ...
4
votes
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)?
4
votes
3answers
123 views

Designing reverse and overvoltage protection at 3.3V

I have a barrel jack powered design that I'm making, but I would like to prevent damage in the case of reverse polarity (sleeve is positive instead of negative) and overvoltage (plugging in a 12V ...
4
votes
2answers
268 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 "...
3
votes
3answers
5k 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
4answers
527 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 ...
3
votes
2answers
855 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 ...
3
votes
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 ...
3
votes
2answers
494 views

Voltage monitor circuit (reverse polarity protection with high voltage cut-off)

I want to make a circuit which performs these tasks: 1) Protect the load against reverse polarity. 2) Protect the load against over voltage. Load = Raspberry pi Reason for this circuit - Pi is not ...
3
votes
2answers
560 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'...
3
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 ...
3
votes
1answer
1k views

A question about preventing reverse polarity for supply rails of an opamp

Below is an example circuit: I have some circuits based on opamps similar to the ones above. I want to prevent a situation if one powers supply rails Vcc and Vee reverse way. Normally this would ...
3
votes
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. ...
3
votes
1answer
54 views

MOSFET selection for high current application

I am designing a reverse polarity protection using the LM74610 chip.Now, my circuit can take peaks of about 90Amps and constant of 50-52Amps. This is quite a load and I want to select the right MOSFET....
3
votes
1answer
64 views

Rectifying reversible polarity battery with minimal power loss

I'd like to build a battery-powered DC power supply that will accept a single-cell battery in either polarity (i.e. it doesn't matter which way you put the battery in). I'm thinking of using the ...
3
votes
1answer
385 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. ...
2
votes
3answers
986 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 ...
2
votes
2answers
990 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 ...
2
votes
2answers
373 views

How do I calculate the diode parameters for reverse polarity protection?

I understand that a diode allows current to flow in one direction only, and that inserting a diode in series with a power source will protect the circuit from a reverse polarity battery. How do I ...
2
votes
3answers
404 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 ...
2
votes
2answers
1k views

What will reverse polarity in an Energizer AAA, unpowered, dead battery, circuit?

Circuit is a three-LED reading lamp. Batteries were left in for "a long time, but it worked last time I used it" according to Mom. Unknown if switch was 0 or 1. All three batteries were inserted ...
2
votes
3answers
4k 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 ...
2
votes
1answer
513 views

LM741 op-amp, converting positive output to negative

I've got a few LM741 op-amps that I purchased by accident months ago, but now I'm in a situation where I believe they may be useful. What I want to do is convert a positive voltage to the exact equal ...
2
votes
1answer
2k 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 ...
2
votes
1answer
77 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 "...
2
votes
1answer
93 views

Can an electrolytic capacitor be charged reversed bias by a small voltage? [duplicate]

In this monostable circuit the C1 capacitor is reverse biased. When T1 is closed and C1 is discharged what will happen on the right side of C1? Will it charge up to 0.6 volts so that T2 can be ...
2
votes
1answer
57 views

Circuit protection component arrangement

I was reading this thread and decided that in general it's better to place the reverse polarity protection diode D2 after the TVS rather than before it, and to instead use a bidirectional TVS for D1 (...
2
votes
1answer
396 views

P-MOSFET allowed some reverse current, L7805CV destroyed. Why?

I was experimenting with reverse voltage protection using a P-channel MOSFET. I hooked up an IRF9510PBF in the following configuration (diagram from Nick Gammon's site, will change if requested): ...
2
votes
1answer
334 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 ...
2
votes
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 ...
2
votes
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 ...
2
votes
1answer
266 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. ...
2
votes
2answers
128 views

How to tell if a capacitor is still good?

I was replacing a 400 V 120 µF capacitor in a power supply (AC 120 V - 19 V DC 4.62 A). I tested the dc out end while it was still plugged in and got 0.07 V. As far as I can tell although being ...
1
vote
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 ...
1
vote
2answers
92 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?
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 ...
1
vote
2answers
761 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 ...
1
vote
2answers
522 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 ...
1
vote
2answers
360 views

Protecting a power supply from inductive load

I recently got a PeakTech 6225A power supply for my hobby of making/"tinkering"/messing around. I get many parts that I want power separately to diagnose them. I also get a lot of electromotors and ...
1
vote
1answer
261 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 ...