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.

Filter by
Sorted by
Tagged with
2
votes
1answer
77 views

Broadband RF noise source/generator

I’m try to make a wideband noise source up to 150MHz, around 0dBm and as flat as possible, based on diode’s avalanche mechanism, plus some buffering and amplification stages. My questions: What is ...
0
votes
4answers
113 views

Math behind Zener resistor for MOSFET Vgs

The following circuit is from Texas Instruments: http://www.ti.com/lit/df/tidrb35a/tidrb35a.pdf What is the math behind the string of six 470k resistors at the MOSFET gate? I know that they are for ...
0
votes
1answer
39 views

Minimum Current for Zener to Clamp Vgs of Mosfet?

simulate this circuit – Schematic created using CircuitLab When it comes to zener diodes I find it hard to get information about minimal currents needed for it to breakdown so I thought I would ...
0
votes
0answers
32 views

simple clamp circuit resistor calculation

Hello guys i want to calculate the resistor R in this circuit.Can anybody help me? The value of zener diode(VZ)=4.8 volt. well i try to simplify it My question is is my solution is right??If not ...
0
votes
1answer
52 views

Transient current capacity of sacrifical Zener diode

The common wisdom is that Zener diodes are suited for only very low power surge protection because of their low current capacity. But what about where it was used as a sacrificial device for clamping ...
1
vote
1answer
58 views

Protecting FET with Zener

In shown schematic, I would like to know by any chance or cause if Zener D9 will get damaged. If yes what are all possibilities? FSK signal consist of 3Hz and 6Hz signal all together.
-1
votes
3answers
114 views

Zener Diode vs LM78XX

To get, say 5VDC, from the AC mains, after stepping down the high AC voltage using a transformer, we have to rectify it and regulate the output DC voltage. As I have seen, there seems to be two ...
0
votes
1answer
45 views

Leakage current of ESD protection diode vs regular zener diode

I am using a voltage divider to measure input voltage, a zener diode was added to protect opamp in case of voltage spike. simulate this circuit – Schematic created using CircuitLab I was told ...
1
vote
2answers
90 views

How do I find a replacement for this SMD Zener diode?

I am attempting to repair a circuit board where this particular Zener Diode is fried. I have attempted to search for any references to Zener diodes that are marked 8•9 (and 6•8) without success. ...
1
vote
1answer
49 views

Under-voltage lockout or linear regular or just a Zener diode?

I have a 200W 5VDC power supply (Meanwell LRS 200-5). When I shut off the AC it takes about 60s for the supply to drain fully through the connected sensitive components (processors and storage drives)....
0
votes
1answer
79 views

Use a dropping resistor or a zener diode?

I have a situation where I need to power an Arduino Uno R3 from a ~16V power supply. The problem is I have no idea of the implications of voltage dropping. I think I just need a 100 Ohm resistor. So,...
1
vote
1answer
79 views

GPIO over voltage input protection

I want to design a circuit that can protect GPIO of the microcontroller from high voltages.the GPIO connects externally to mechanical switch. So my approach was to use zener diode to clamp the high ...
0
votes
1answer
59 views

Zener diode (Power rating exceeded)

The following is an exam question I encountered. In the above circuit the current across E is 180 mA. Since the current across 300 Ohm resistor is 13.33 mA, there will approximately be a current of ...
2
votes
2answers
160 views

Would this protection and limiting circuitry work with 5.1V zener diode?

I have a small project for part of an experiment where a PWM controlled DC fan speed will be controlled by a -10/+10V function generator's analog DC output. So basically the chain will be: Analog ...
2
votes
1answer
32 views

esp32 driving zener diode with 2.9v threshold at the gpio

If I want to drive the Zener diode with the ESP32 GPIO, will that be appropriate? What factors to look in this case? I want this as a low voltage detector?
0
votes
1answer
54 views

reading a high negative voltage with attinys running on batteries

I need to read a negative input voltage from a camera flash capacitor that can charge up to -330V. I am using an attiny85V that is running on batteries and want to set the internal reference voltage ...
3
votes
1answer
103 views

Analog input over-voltage protection using Schottky and Zener Diodes. Can it work?

I'm developing an analog input module based on TI's ADS8668 and want to protect the input channels from over-voltage. According to the datasheet, each analog input channel withstands voltages from -...
1
vote
1answer
72 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 ...
2
votes
3answers
237 views

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 ...
0
votes
3answers
93 views

Zener diode purpose

Can someone explain what the purpose of D3 & D4 are in this circuit?
0
votes
1answer
53 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 ...
0
votes
0answers
41 views

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-...
2
votes
4answers
101 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 ...
1
vote
2answers
64 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 ...
0
votes
2answers
83 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 ...
-1
votes
1answer
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 ...
0
votes
0answers
61 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 ...
3
votes
1answer
106 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 ...
0
votes
1answer
65 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 ...
0
votes
1answer
105 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 ...
0
votes
1answer
196 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 ...
0
votes
4answers
102 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 ...
5
votes
2answers
1k views

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 ...
0
votes
2answers
64 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 ...
1
vote
3answers
228 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 ...
0
votes
0answers
52 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 ...
0
votes
1answer
56 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 ...
0
votes
1answer
78 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? ...
1
vote
1answer
110 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 ...
1
vote
2answers
106 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 ...
2
votes
1answer
95 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 ...
0
votes
1answer
208 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? ...
4
votes
2answers
79 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 &...
1
vote
3answers
111 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 ...
0
votes
2answers
48 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 ...
3
votes
1answer
143 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 ...
-1
votes
3answers
143 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 ...
0
votes
1answer
50 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 ...
1
vote
1answer
235 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.
0
votes
2answers
158 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 ...