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. ...

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133 views

Reducing Ripple in the Zener Regulator

In the Art of Electronics (Horowitz & Hill) the following circuit is given as a solution to reduce ripple current caused be variations in input voltage (pg. \$ 69 \$): "An alternative method ...
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147 views

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 ...
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2k views

Why are there so many resistors in a typical schematic?

I know that some resistors cause pull-up or pull-down or work as a voltage divider and/or current divider. But sometimes I cannot understand their function in some simple circuits: Take this motor ...
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130 views

A series resistor behind a reverse biased zener diode

simulate this circuit – Schematic created using CircuitLab If the Zener is rated at 4V, and the resistors R1 R2 are both 300ohm, may I know what is the value for Vout? I know this is a ...
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4answers
137 views

Zener + MOSFET overvoltage protection

I need a simple circuit to protect my device from overvoltage (more than 13V). Typical working DC input voltage is 7-12V. Can I use this circuit: Will it work? UPD. OK, it will not. I was too ...
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1answer
34 views

Reverse biased breakdown

Is the reverse biased breakdown of a rectifier diode a reversible process? (that is if the voltage is reverted to a value within the specification range will the diode behave as expected of an ...
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1answer
142 views

LM7805 and Zener Diodes

I'm boosting an LM7805 to 16V using Zener diodes in series at the GND pin (pin 2) of the 7805. The Zener Diodes I'm using are 1 of each of the following: 3.3V, 3.0V, and a 4.7V. Now theoretically I ...
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53 views

Why are resistors used in a Zener clamp circuit?

A data acquisition channel is fed by a signal which first passes through a clamping circuit as I draw below. Here in the figure Output goes into the data acquisition board after a 8V clamp circuit: ...
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173 views

Zener diodes Eagle library

I need to make a PCB, and the only software I have is Eagle. All the other parts are listed in my libraries, but where can I find a library that has DIODES INC. - MMSZ5226BS (Zener diode)?
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98 views

Accurate -2V reference

I have an old Keithley 175A multimeter that has been suffering from a bit of drift lately. Internally it uses a 6.35V zener and a couple of resistors to create a -2V reference, but the zener is ...
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134 views

Using a Zener for reference voltage

I want to use a 9.1V Zener diode for a ref voltage into a op amp comparator so that when the battery voltage (11-12V DC) drops below 9.5V DC it will cut the supply to the circuit via a P-channel ...
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82 views

Is this a Zener Diode? UPDATE it just turned into dust :( phone still turns on, what the…? O_o

my Nexus 4 usb connection died and when opening it I found a burnt component which looks like a zener diode, it could be a transistor though, I need help identifying this component so I can replace ...
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170 views

Intrinsic Zener diode in MOSFET

I understand why some transistors have a built-in (normal) diode from drain to source, so that when the transistor turns off, back-emf can flow back up, specially important in inductive charges, but ...
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2answers
94 views

Zener diode BZX55C3V3 does not behave as Zener diode

I have bought a couple of BZX55C3V3 diodes to protect the ADC inputs of the microconroller but I noticed they all behave strange (and each one in a different way). This is a ST 3V3 diode ...
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1answer
58 views

Zener Diode Identification/Replacement

I am seeing if I can trace out remake some circuit boards laying around. For this particular board, I can identify all parts except this diode. The part number is CK 2EZET (I am only assuming it is ...
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4answers
255 views

Zener diode as voltage regulator

I've been trying to make a voltage regulator using a zener diode. I used the BZX79 3.3V Zener diode. I connected the diode as the following: Data Sheet. I assumed that as as most of them it ...
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1answer
87 views

How to decipher zener diode encoding?

I'm new to electronics and I'm trying to reverse engineer the circuit board in an R/C car. I've come across a diode and it is labelled... C3V3 5T 1) I assume ...
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1answer
103 views

Can a Zener diode be used in place of a Schottky?

I want to use a LM226677 Voltage reagulator to achieve a step-down converter from 12V to 10V. However, in a Schottky diode is used reversely polarized at the output of the LM22677, and the datasheet ...
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1answer
143 views

What is purpose of zener diodes in this circuit?

I am reading the I2C tutorial: https://learn.sparkfun.com/tutorials/i2c/all Why wouldn't it work without the zener diodes? What functionality are they adding? They are just there to keep the voltage ...
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2answers
113 views

Zener Diode - Vz0

Theoretically, what is the importance of Vz0 in the following figure. When modeling the zener diode, why is Vz0 used over the diode's given Vz? For modeling, I was given the formula Vz = Vz0 + ...
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1answer
172 views

Using a Zener to protect devices from solar overvoltage

I am making some pretty crude devices that are directly powered from solar panels. The instability is not an issue, but I want to avoid over-voltage. I am using two 100W panels in series and want to ...
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1answer
117 views

DIODE as capacitor?

How does Diode act like a capacitor when voltage across diode is less than forward voltage spec. Basically when diode is turned off? What is its usual capacitance when diode (zener) is turned off.
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614 views

Why do we need many complex voltage references when a zener can do the job

There is a huge variety of Zeners that exist. They have varying breakdown pd among other things. Why then do we need voltage references that are more complex and made up of many components?
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1answer
99 views

Use voltage regulator instead of zener to protect GPIO

I've read several articles about protecting 3.3v GPIOs from unregulated over voltage, all of which involve using a zener diode, a diode for reverse protection and resistors in some fashion. example 1 ...
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69 views

Surge suppression for electric motor

I have a 4.2W 12V electric water pump connected in series with a water float switch as a sump pump, powered by a 1A 12V DC power brick. The switch has a maximum switching voltage rating of 100V. ...
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108 views

Reducing voltage for solid state relay

I have a solid state relay which wants a 1.25-2.5V "activation" input, but my output from the micro controller is 5V. Is it possible to use a zener diode for this? Or do I need a buck converter? I ...
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4answers
269 views

Why does the voltage of a zener diode match the voltage at Vout?

In this circuit, if: Vin = 9V Vz = 5V I understand that Vout will be 5V. Does that have to do with Kirchhoff's Voltage Law? How does the zener diode, if it drops 5V to ground, cause Vout to also ...
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55 views

Low current input source - current limiting resistor for z-diode needed?

I have a very low current input source (tiny solar cells) with a maximum short circuit current of 80µA which are loading a supercapacitor (1F/5.5V). To protect the supercapacitor from damage I added a ...
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2answers
441 views

MOSFET controlled by optocoupler using Arduino

I have a question about using an Arduino to control a MOSFET with optocoupler. The question is, the supply voltage may vary from 5 to 36 Volts. For example, sometimes I will use a 5V switching ...
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5answers
572 views

Using a Zener diode to ease a voltage regulator

I was reading a tutorial on how to hook up a zener diode to ease a voltage regulator. Here if you follow this link, as one can see the zener diode is dropping some amount of voltage to ease a voltage ...
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1answer
120 views

Cost-Effective CPLD micropower 1.8V from regulated 3.3V

in my design a ispMACH 4032ZE CPLD (32Macrocells) operates as SPI slave driven by a moderate 8MHz master-clock. The part requires a 1.8V core supply drawing (estimated) tiny 100uA over the full ...
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1answer
262 views

Using a piezo disc as an input and output device to ATtiny85

I am working on an art installation and plan to use a number of these small circuits to make sounds, to sense sound/vibration and also to move the device (using a triangle wave output). This link ...
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1answer
204 views

Transient Voltage Suppressor (TVS) Diode Array

I am having a hard time understanding this logic. Please bare with me if my question is very basic. I would appreciate if someone can explain what is happening? If I look into any typical TVS IC data ...
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4answers
604 views

NPN Transistor in common collector configuration, Vout varies

I am trying to make a power supply which gives a constant 5V at output with a current limit of 1 Amps. I am using D1047 NPN transistor in common collector configuration, with 5V (low current) voltage ...
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1answer
141 views

Determine material of Zener's diode based on its characteristics

I have a plot log (I) = f(U) for a few diodes: Silicon diode, Germanium diode, some LED and a Zener diode. I need to determine the material, from which the Zener diode is made based on the positioning ...
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3answers
94 views

Calculating resistance for zenor diodes?

I am an electronics student, and I was set some homework online. Am not having trouble with the question itself but the theory. It says that the current through the resistor is the same as the ...
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1answer
272 views

LM431 Reference Pin Current High?

I'm working with the LM431, and have successfully observed it regulating voltage in a series pass configuration. The goal is to regulate an input voltage of up to 0-5V to a maximum output voltage of ...
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2answers
777 views

How to use zener diode for negative voltages?

Every one may be familiar with zener diode function in positive voltages but I don't know how to use them in negative voltages. For example in the schematic below, if we use a 10v zener and the ...
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2answers
416 views

LM311 circuit not working

Further to my two, other questions about Zener diodes to detect when an automotive battery is being charged by the alternator, I've developed the following: Note: The Fritzing tool I used doesn't ...
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3answers
992 views

Zener diode can vary current flow to maintain voltage drop, how does this magic effect work?

So it seems that a zener diode is "magically" able to change its resistance to allow more current to pass through it, such that the voltage drop across the diode remains the same. My question is ...
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2answers
141 views

Reopen zener diode after reverse bias breakdown

I've been learning about using zener diodes to generate a reference voltage for a small comparator circuit, the intention is to detect when a motorcycle battery is charging (i.e more than 13v), and ...
3
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3answers
271 views

Basic comparator strange problem

I am trying to create a super simple Low Battery alert monitor, by utilizing an open-loop comparator. LBO is active-low - it's connected to a TTL input pin of a uC, running from same Vbatt voltage. ...
5
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3answers
3k views

Why do we connect a resistor before a Zener diode?

Why do we need a resistor in a Zener diode circuit, like in the diagram below? I understand it is to limit the current but how so, and why do we need it for a Zener diode? Does selecting different ...
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2answers
522 views

Why is a Zener diode in a crowbar configuration dropping the input voltage?

simulate this circuit – Schematic created using CircuitLab I'm trying to hook up a Zener diode in order to add some measure of protection (fused "crowbar") to a circuit that includes a ...
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1answer
890 views

How to calculate minimum zener current if it is not explicitly specified in the datasheet?

simulate this circuit – Schematic created using CircuitLab I'm going to use 1N4740A as a voltage reference in a similar way you see in the schematics above. In textbooks, a zener property ...
7
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2answers
1k views

Using 1N4148 As A Temperature Sensor

Can I know which component senses heat or acts as heat sensor in the following circuit? In the given diagram, it is said that the 1N4148 diode acts as the sensor. But basically it is a zener diode and ...
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229 views

Switching and Zener Diodes

What's the difference between a Zener Diode and a Switching Diode? I.e: 1N4148 (switching) vs 1N5225 (zener).
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2answers
1k views

Zener Noise Generator - NPN BJT Amplifier Analysis

I'm interested in creating a low voltage white noise generator by means of a zener diode, as detailed here: Zener & BJT Noise Generator. Specifically, I want to use the circuit here, in order to ...
2
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2answers
1k views

Alternative to emitter-follower for simple BJT voltage regulator

I want to make a voltage regulator from one or two BJTs and a zener diode. However, I would like to be able to make full use of supply voltages when they are lower than the voltage that the regulator ...
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1answer
449 views

Using Zener Diode for 12v input to Arduino

The MPGuino uses a 5.1v zener diode to read an input from the switching of an injector. According to my very basic understanding of how zener diodes work I used the formula: $$ I_{diode} = ...