Questions tagged [zener]

An effect in semiconductors, the name of a diode that uses that effect and more generally any diode that has similar characteristics to a zener diode. Zener diodes have the unique characteristic of a reliable reverse bias breakdown voltage. Often used as simple voltage regulators or level shifters. Zener breakdown is a distinct effect common usage is any diode that has a fixed reverse breakdown are called "zeners" even if the mechanism is different.

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360 views

Design a Li-Po battery charger with small solar panel and charger controller with embedded MPPT

I'm designing a small solar charger with these characteristics: SOLAR PANEL Voc = 5,65 V Vmp = 4,25 V (Voc -25% approx.) Isc = 250 mA IC CHARGER CONTROLLER STMicroelectronics SPV1040 High ...
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188 views

3 terminal regulator max input voltage with zener at adjust pin?

Quick question: If I stick a zener at the adjust pin of a 3 terminal linear voltage regulator, the allowable maximum input voltage will also increase by the breakdown voltage of the zener used... ...
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339 views

Voltage regulator with zener diode

What is the maximum input value (Vi) that can be applied without zener diode gets damaged knowing that the maximum power rating of the zener diode is \$ P_m = 500mW \$,the breakdown voltage is \$ V_Z ...
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166 views

Op-amp circuit analysis without input signal

In the following circuit i need to find the OUTPUT and the current that flows in the zener diode D1, which works at the "zener" breakdown region with $$Vzener=5,6V$$ The opamp is considered to be ...
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2k views

Op-amp with zener diode

In the following circuit i want to find the output voltage Vo related to the input Voltage Vi. Diodes D1 and D2 are the same and have a 0,7V drop when they conduct. Op-amp is ideal too. For the zener ...
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475 views

AC 20V to DC 5V converter with zener diode question

I have this AC 20V to DC 5V converter with zener diode circuit. It works as expected if there is no load connected. As soon as I connect the load, in this case LED diode with 20mA consumption, the 5V ...
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299 views

Transimpedance Amplifier (TIA) - How to shunt high current spikes?

I am working on the design of a high-bandwidth transimpedance amplifier (TIA) to detect a relatively weak optical signal (100μW) but also be able to withstand short pulse, high power optical signals (>...
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Why would you bypass a zener diode in the flyback protection of a relay coil? [duplicate]

SparkFun sells a relay control kit that you solder together. On the back of the circuit board there is a pair of metal contacts that are labeled "bridge for zener bypass". I assume you put a small ...
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On a relay coil, why use an MOV instead of flyback diode?

I briefly encountered a designer who wished to use an MOV instead of a flyback diode with a relay coil. I don't know much about the application, but why would you want to do that? The only reason I ...
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Purpose of second resistor in zener-based voltage regulator with low-pass filter

Trying to understand the purpose of the lower resistor R in this example from TAoE The upper resistor R and the capacitor form a low pass filter, but why the lower resistor R? What would change if it ...
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768 views

Zener diode for solenoid

I am new in electronics and this is old subject but still. I started new Arduino project where I control 4 solenoid valves independently via Arduino 4 chanel 5 V Relay module. From the beginning I put ...
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198 views

Sizing zener and resistor for solenoid flyback

I am trying to drive a vibratory pump from a 220 V boost converter (the common 150 W DC/AC 12 V to 220 V boost converter found on ebay) and a MOSFET switched by an Arduino/optoisolator at 50 Hz. The ...
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105 views

Adding a temporary load to a power supply

I have an isolated switching power supply which takes in 30V and outputs 55V 1.5A. It's a power source for a PoE+ powered device. When the device which is supposed to be powered is not connected (via ...
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546 views

Art of Electronics - Zener Diode Example

I'm working through the Art of Electronics and I'm stumped by a zener diode example. The text presents this circuit: And then shows that the zener diode behaves like a voltage divider: \$R_{dyn}\$ ...
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745 views

Unstable 11-13.8 volts to 12v regulator. DC-DC buck or Zener diode, how to do it better?

I have 12v power source Mean well PSC-60A with UPS function and acid buttery. In datasheet says, that output can be regulated from 12-15V - but it's not true, because tested results for output was: ...
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339 views

GPIO input protection

I know this subject has been covered but I have a specific question regarding zener characteristics for microcontroller GPIO protection in vehicles where nominal voltage could be 12 or 24VDC. ...
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Li-Ion battery status indicator LEDs with zener diodes

I've just inherited a project from another engineer with zero overlap. Looking at the schematic it seems that they've attempted to include two battery status indicator LEDs through the following ...
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Why is Zener avalanche noise saw tooth shaped?

I have the following schematic of a Zener based noise source:- simulate this circuit – Schematic created using CircuitLab When built, an oscilloscope reveals a saw tooth noise signal at the "...
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457 views

Zener dynamic resistance Rz: Is this graph or the values for Rz correct?

The textbook I'm studying from states that the typical dynamic resistance ranges from 1 Ohm to 50 Ohms. Seeing the following graph something doesn't make sense: Since the slope in the breakdown ...
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Transformerless power supply

I'm looking for building a power supply circuit that will convert 230VAC to 5VDC in order to power up an Atmega328P. I also want this to be as small as possible. I know a transformer is one option ...
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321 views

Circuit with Zener-Diode not working (simulation do)

Hello, I have the circuit shown above. Its made to measure analogue voltages up to 10V and converting currents up to 20mA to a voltage output. 10V or 20mA = ~3.3V output Now I want to test the ...
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621 views

Protecting BJT base-emitter junction from breakdown voltage

I was playing with a BJT based circuit and I learned about the breakdown voltage of BE junction. I came out with a solution of connecting a diode in series, with higher breakdown voltage. But I am ...
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738 views

voltage cutoff for very low voltage (0.5v) [closed]

I have a circuit that I want to not allow any voltage to go over 0.5v. I read the voltage with ADC and the input can go from 0v to 0.5v and what I want is a circuit that will keep the voltage 0.5 even ...
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246 views

Non-resettable zener/polyfuse for overvoltage protection

My setup is two DC-DC converters (hobby BECs) supplies, one acting as a backup for the other. A relay, powered by the primary BEC will automatically switch to the secondary BEC if the output from the ...
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607 views

Zener Diode Voltage and Curve Equation

I am trying to figure out the zener voltage of 1n4742a zener diode. I constructed the following circuit: The data sheet of the diode can be found here: http://download.siliconexpert.com/pdfs/2016/8/...
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421 views

What function does this PCB circuitry serve?

Backside is metal disc with thermal paste between it and the metal mount to which it is screwed. Input is 6.75V 200mA. What function does the PCB circuitry serve? Is it stepping down the voltage or ...
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226 views

Additional overvoltage protection after RBO 40-40 with Zener diode

I have an automotive application where I have this: simulate this circuit – Schematic created using CircuitLab Would the 20V 1W or 5W zener diode be enough together with a typical automotive ...
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2answers
1k views

Zener Diode vs Precision Voltage Shunt

What is the difference between a zener diode and a precision voltage shunt? From the name I am guessing that the precision voltage shunt is more precise. I am using the shunts to limit the output of a ...
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How good is to use this zener diode for reverse polarity protection?

In the following circuit how does the zener diode D1 provide reverse polarity protection? Lets say V+=12V and V-=-12V and the zener is 36V zener. It means for correct polarity zener will not pass ...
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Understanding Zener diode datasheet

I am a beginner in electronics, and if you have a look at my profile, you'll understand that I'm completely confused in nomenclature of components. I recently downloaded a datasheet of a Zener diode ...
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1answer
793 views

Calculating parasitic capacitance of serial zener diodes

simulate this circuit – Schematic created using CircuitLab I have 2 series zener diodes like these in the schematic. Their capacitance is C=225pF How do I calculate their equivalent ...
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883 views

How to test high voltage Zener Diodes with multimeter?

Given an unknown Zener Diode taken from a circuit board, is it possible to measure the Zener Voltage without a datasheet? I tried to make a circuit like the one below and I add batteries in series ...
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Building A Voltage Threshold Indicator with Wide Voltage Window (0-600V)

Background: I'm from A Formula SAE Team designing a building a EV to Compete in an FSAE Competition. Situation: We construct an Accumulator that houses the batteries and related components. This ...
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What exactly is the definition of a voltage regulator?

I was assigned to design a voltage regulator for a secondary ECE circuits class, and I would like to know precisely how that element is defined, given the following. It has an input and an output The ...
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405 views

Calculating the peak voltage of a zener diode output

I have a problem with this homework, I have to calculate the peak voltage of the output after stabilizing with a zener diode. My Input Voltage is Vin = 5V + 0.7Vsin (2pif*t) with f=10kHz My circuit ...
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521 views

Help analysing a discrete voltage regulator circuit

I need a -140V reg which doesn't exist, so I'm trying to learn how to build simple discrete regulators (starting with positive regs). As I only need a few tens of milliamps with a fairly constant load,...
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716 views

BJT Circuit Problem [closed]

I am facing problem in solving such mixed circuits with bjt, diode, opamp and Zener diode. In the above problem 1.zener can have 3 states (ON, OFF, Reverse ON) 2.diode can have 2 (ON, OFF) 3.BJT ...
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347 views

Expressing output voltage in a circuit with zener diodes without any value given

I have this circuit and I need to find \$u_{o}(u_{i})\$ if \$ZD_{2}\$ and \$ZD_{1}\$ are ideal zener diodes with \$U_{z}\$ zener voltage and the op-amp is also ideal. My problem is that I have no ...
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773 views

Switch voltage output with Zener diodes in series

I´m trying to produce a power supply that can give an output of both 24V and 12V. I want to switch between these two voltages with a signal of 5V, when the signal is low i want to get out 24V and then ...
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1answer
436 views

How do we derive the limiting values of a series’ resistance for Zener diodes with varying load and varying input conditions? [closed]

Is there a mathematical derivation for finding the limiting values of series resistance in a voltage regulator circuit with varying load and varying input conditions ?
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MCP73831: design a lithium battery charging circuit

I am trying to design a charging circuit for a lithium polymer battery with 2200 mAh capacity and 3.7 V nominal voltage. The integrated circuit for the control of the charge of the battery is the ...
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Find the Min Value of R in a Zener-Transistor Regulator

It's my first time here, and i'm starting asking a question, but I hope I can help some people in the future. So, my Teacher showed this exercise to us and i'm wrapping my mind around it without ...
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242 views

What is the output voltage in this case?

What happens when the output voltage of an op-amp (say in a voltage follower/inverting configuration) should be higher than a certain amount (say 10V) and on the output I place a 5V zener diode in ...
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MOSFET protection using zener diode

I have a question about this circuit, using Zener diode as a protection for mosfet. I've found some related topics but didn't found any circuit which uses the same configuration. Can anyone suggest ...
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920 views

Half-Bridge MOSFET Driver for 48V

So I designed this Half-Bridge Mosfet Driver for 48V. Since I'm pretty new to this type of circuit I would like to ask if there are going to be any problems with this circuit. (eg. speed, power loss, ...
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Current sensing application

The purpose of the application is to maintain a constant current at the load, even if the resistance changes. I understand that the ADC is reporting the voltage and current values at the load to the ...
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MOSFET Gate protection

I am using SSM3J334R P channel MOSFET for switching high voltage which has following specs Drain-Source voltage (VDSS) -30 V Gate-Source voltage (VGSS) ±20 V ...
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3answers
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Current distribution for parallel zeners

Suppose you've got two 5V1 zeners in parallel. Due to slight differences between the two parts (tolerance on zener voltage), one of them will conduct more current. simulate this circuit – ...
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A question regarding sizing some resistors in a circuit

I have the following circuit's old version soldered which works fine in real. The updated circuit in the below diagram exists only in simulation. Recently I will in real add a zener with a series ...
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1k views

Use LED instead of Zener

I'm planning to assemble a circuit this weekend; it is basically an attiny85 with a USB interface. The circuit is well known on the internet; see for instance this schematic: (Image taken from http://...

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