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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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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66 views

How to regulate voltage across capacitors

This is a charging regulator, and with over voltage regulation across Cload, which is used to provide power for up to 3ms in case of a power micro cut. What I do understand in this schematic : How ...
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129 views

How to mathematically simulate a zener diode

I would like to simulate a circuit with a resistor and zener diode for various voltages in an excel spread sheet and need a way to model it.
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Make a zener diode out of a MOSFET

Does anyone know if its possible to wire up a MOSFET transistor as a zener diode? I have been happily making normal diodes from my MOSFETs by shorting the gate and the source simulate this circuit &...
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Understanding this power supply design

I'm doing some kind of reverse engineering to this very old power supply design. I'm having hard time trying to understand it all. I'm asking for some hints that help me read this schematic. From this ...
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150 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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420 views

Op Amp as a simple switch

I want to build a little voltage switch that switches on a buzzer and a relay when a certain voltage is reached. Please have a look at the schematic. I use a trim potentiometer to set up the switch ...
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82 views

Zener diode purpose

Can someone explain what the purpose of D3 & D4 are in this circuit?
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48 views

Turn on power when voltage higher than set value

We are trying do design a circuit which works by harvesting energy from a split core current transformer. Most of the electronic works correctly, we use a 1.5F 5.5V SuperCap to provide enough power ...
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182 views

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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192 views

Driving a 35V PMOS circuit from a Grounded/Floating input

I have an application where I need to switch a contactor on and off using a spare output of an off the shelf Battery Management System (BMS) The input is the signal coming from the BMS, while the ...
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535 views

24V H Bridge Gate driver - FOD3184 & FQP47N06

I am trying to design a H-bridge to drive 24V motors. No issue on the low side but I would like to use the FOD3184 Opto/Gate driver on the high side of the H-bridge to drive a P MOSFET and I am ...
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Simple braking chopper using Zener/TVS diode

So I'm designing a motor controller, relatively low power (100-150W, 12-48V supply), and I'm thinking about adding a braking chopper. Not strictly needed in this design, but it would be a nice value-...
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459 views

Dimensioning SCR crowbar circuit

I need to dimension an SCR crowbar circuit to reach a certain level of protection against overvoltage, without increasing much the complexity of the circuit of my control card. The need is to protect ...
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99 views

Is this way of sizing the series resistor for Zener regulator correct?

This is a completely made up imaginary question to ask the question easier. Let's say I have a 0.1W 5V Zener diode. And I want to use this to regulate from 9V to a 10k load. I draw this as in the ...
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51 views

Zener temperature derating

Can someone explain what the Ta line on this zener diode temperature derating graph means please. The diode is an MCC SMBJ5338B 5.1V 5W zener. I understand the lead temperature (TL) line means ...
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79 views

How do I know that this BJT is in the saturation zone without having to simulate it?

I have to find the working zone of this BJT, for different values of P, by using a simulation software like Simulink. But I would like to know how to do it manually. The way I learned is sort of ...
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50 views

BJT Cascade Difference Amplifier Exercise

I need help with the exercise. The questions: Add or Design Components to have a current source I=2 mA at the picture. Draw equivalent small signal,low frequency model. Find Ai, Zo, Zi. If ...
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1k views

How do TVS diodes work?

I'm aware of how Zener diodes can work as voltage clamps, but how do TVS diodes work in terms of physical construction? The Wikipedia article explains what they are used for, and a bit about their ...
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86 views

How do I size a zener diode for use as a freewheel diode for a ZVS induction heater?

My electronics experience is "hobbyist" and I'm in some new territory with this question, so forgive me if this question turns out to have an easy answer or prove to be dumb. I have a basic ZVS ...
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57 views

Use zenerdiode as voltage threshold circuit

My garage door opener has output terminals that output 10V as idle and 24V when the opener is running. I have the output connected to a 24V relay to control the lighting in the garage. My problem is ...
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54 views

Input circuit - Current and Voltage calculation

I have Input voltage : 6.5V Zener breakdown is 3.6V. Does the 3.9K and 4.7k ohm resistor acts as a voltage divider? or what purpose does the 4.7k ohm serve? And can someone help me how to ...
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64 views

Pulldown for zener voltage shifter

I would like to know whether R24 has been correctly applied to pulldown the EN pin when none of the diodes are switched on. The idea here is that voltages higher than 3.3V may be applied from any of ...
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118 views

Zener diode question in simple LED circuit with anti-flicker for model railroad

I am a total novice when it comes to electronics. I had a simple circuits class 30 years ago as a software undergrad. I've designed a simple LED lighting circuit for N-scale model railroad, to be ...
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92 views

Voltage error when connecting a zener diode

I am working on a project where i need to measure the battery voltage and send the measurement to a uC, which is powered by 3.3V. The voltage divider is projected as shown before: As input we have ...
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Can a zener diode with a higher power dissipation be used in place of the original one in an audio amplifier?

Following my Marantz PM-68 repair question, I would like to change a faulty zener diode used in the amplification stage. I don't really understand the purpose of this diode but I guess it's used for ...
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164 views

Overvoltage protection with zener - How do you get a sharp knee clamp for analog input?

I'm working with an MCU that sees a 0-5V input range. I have a possibility where they may accidentally see 12V (user error). My problem is this analog input using a 5V Zener has a knee that isn't as ...
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56 views

Relay Driver with 24VDC Relay… Zener diode?

I am part of a physics project group, and we are trying to design a relay driver. Our Relay is rated at 24VDC (it is a Tyco Electronics 1432826-1). What zener diode (or regular diode if that would ...
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5k views

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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41 views

using a TVS in place of a zenner diode

I have read somewhere that a TVS is nothing else than a robust Zener diode. My application requires using 300V zener diodes (that may exist but do not pop up so easily), but TVS at 300V are very ...
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7k views

Differential resistance for a zener

I'm reading the BZX79 datasheet. On page 4 it lists differential resistance at 1mA and 5mA. For instance for the 3V version differential resistance is typical 325\$\Omega\$ at 1mA. Would that mean ...
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48 views

Disambiguation of Anode and Cathode Terms in Diodes

In a regular silicon junction diode the positive side is the anode an the negative the cathode. But when someone uses a Zener diode that operates in reverse bias there is a problem with what ...
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62 views

Over voltage protection for a buck controller 24V in. 4-5V out

Please see Image below, if the output votlage here is 4-5V with current out 3A-15A(depending on LOAD). Could I stick a Zener diode to clamp any over voltages to protect the load from over voltages? ...
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100 views

zener diode circuit analysis

I'm studying Zener example and it doesn't make sense to me: the Example - with solution in the above picture i can see that input is 26.4V and Zener voltage 14.56V. when load 1k connected. but in ...
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104 views

Reduce Noise Added With Zener Clipper

I'm working on a hobby Arduino project to create an audio visualizer using an LED strip. I'm using the MSGEQ7 to separate the signal into 7 bands, then send it to a Wemos D1 Mini. I started by ...
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79 views

Can Zener or Schottky diodes be used as a substitute for varicap diodes in tuning a VCO?

In particular, this would be a fairly low frequency VCO with a frequency range of 10 Hz to 20 kHz. I'm thinking of the configuration with the T-junction that has 2 opposite facing, reversed biased ...
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164 views

Confusions with placing and sizing the flyback diode, TVS and Zener

I have couple of questions regarding the location of flyback diode and sizing and locating the Zener and TVS diodes. For example below at the far end there is a magnetic relay which is controlled by a ...
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77 views

Use zener diode as regular diode

I have a circuit that uses regular diodes, and I only have zener diodes in hand. As I understand, zener will conduct after a certain voltage in reverse, so all I have to do, is pick a voltage that is ...
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149 views

Zener diode parallel to RC circuit

In the left hand side part there is a diode in series to parallel RC network. And in the right hand side there is a zener diode in parallel with series RC network. How do these sub circuits operate? ...
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83 views

Over-voltage protection system for a 7 - 20 A Load with 4 - 5.5 V output from PSU

The power supply used on the product, is a DC-DC buck controller 24 V in (3 - 5.5 V out). I need some suggestions to help protect a load (LED Display) which draws roughly 5 - 15 A the power supply on ...
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77 views

Load resistance in voltage regulator

I want to find the minimum resistance \$R_L\$ so as to maintain \$V_z\$(voltage of the zener corresponding to the minimum current \$I_{z_0}\$) across the same resistor \$R_L\$. simulate this circuit &...
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118 views

8.6 ohm resistor is decreasing 3.97volts to 2.95 volts which is connected to zener diode i can't understand how it is happening

i'm trying to pass 3.3v to nodemcu from a 4v battery, For that I'm using a resistor of 8.6ohms and a zener diode of 3.6v. and the circuit diagram is as follows but when i simulate the circuit in ...
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46 views

What could be the output current rating of the following shunt regulator?

I am trying to solve the 2013 paper set by ISRO for electrical engineers. I wanted to verify if my answer to Question no 18 is correct. So \$I_L\$ is being drawn out of the circuit shown. Since the ...
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123 views

How to find voltage on zener diode while there is a current source

simulate this circuit – Schematic created using CircuitLab I'm confused about whether zener is on or off due to not being able to know voltage on V0. I tried to find by applying KCL & KVL, ...
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128 views

Using a zener diode to limit current to an IC for various input voltages

I'm designing a board based on TI's DRV110 solenoid driver. The datasheet explain that: "The DRV110 is able to regulate \$V_{IN}\$ voltage from a higher external supply voltage, \$V_S\$, by an ...
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129 views

Battery indicator Circuit

Many of battery indicator circuits are designed using 2 or more leds like in the image above but how to design a simple battery indicator circuit using only RGB LED and transistor for 12v battery ...
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49 views

What is the purpose of a schottky/zener couple on an isolated flyback topology?

This isolated flyback topology has been generated by TI's webench. It's a classic schematics with a feedback going through an optoisolator. There are, however, two diodes connecting the switching ...
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126 views

Mosfet Gate-Source Zener [closed]

I want to confirm this circuit is going to work and ask how to calculate the zener voltage. The load is going to be driven by 30 volts, and the gate voltage is the same 30v, through an optocoupler.
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142 views

What is the purpose of these diodes in this opto isolator circuit?

I came across this circuit which I think is to isolate a high voltage signal to a safe level for GPIO of a 3.3V micro controller. My question is that how on earth this circuit works...There are 2 ...
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141 views

in zener diode current source, to provide constant current, what resistor, etc do I have to use?

I have a load that has varying resistance and want to know the change of resistance by measuring the voltage with constant current. The figure below is known to provide constant current. But I have no ...