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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63 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
52 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
121 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
58 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
116 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
105 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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525 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
58 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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2answers
48 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. ...
2
votes
2answers
92 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 ...
2
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4answers
150 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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1answer
45 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 ...
4
votes
2answers
241 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 ...
0
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5answers
278 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 ...
3
votes
1answer
97 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 ...
3
votes
1answer
155 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 ...
2
votes
1answer
129 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 ...
3
votes
4answers
269 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 ...
0
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1answer
108 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
77 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 ...
0
votes
1answer
169 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
393 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
277 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
650 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
114 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
votes
3answers
248 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
votes
3answers
1k 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 ...
9
votes
2answers
433 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 ...
4
votes
1answer
399 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
votes
2answers
999 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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1answer
154 views

Switching and Zener Diodes

What's the difference between a Zener Diode and a Switching Diode? I.e: 1N4148 (switching) vs 1N5225 (zener).
3
votes
2answers
710 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
votes
2answers
841 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 ...
3
votes
1answer
371 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} = ...
6
votes
2answers
315 views

Purpose of Zener Diode in Circuit

Can anyone please explain what the purpose of the zener diode is in the circuit shown? The circuit is taken from Figure 3 in the datasheet for the STN1170, an OBDII interpreter IC. simulate ...
3
votes
3answers
595 views

what happens if I apply a negative voltage across a zener?

I have the following circuit (just the input portion of a larger circuit):: The 6V is coming from a walwart or other 6v source. The Schottky diode (UPS120) is there to guard against the input ...
3
votes
4answers
281 views

Why is zener current preferred to be more than load current in a voltage regulator?

In a simple Zener Voltage Regulator, such as this Why should current passing through the zener diode(zener current) be more than the current passing through the load(load current)? or No such ...
5
votes
2answers
297 views

Is my zener diode labeled wrong, or am i seeing a strange failure mode?

I'm experimenting with a power supply circuit to bring 24VAC down to 5VDC. I have an L7805CV, but rectified (a bridge) and smoothed (a 33μF electrolytic), the input is still \$40V_{peak}\$, which is ...
2
votes
1answer
434 views

Floating Voltage to Bias a P-Channel Mosfet without Exceeding Source-Gate Max Voltage

I'm not sure if this is what you'd call "floating voltage" or not. I'm lacking on some terminology so bear with me. Here's the circuit with explanation below: The premise of the circuit is this: ...
0
votes
1answer
147 views

Low voltage/current power supply for wide range of inputs

I was thinking of simple low voltage/current power supply that can accept wide range of input voltages, up to the hundreds. Let's say, the input is 20 to 160V DC and output has to be 10V with 20ma ...
2
votes
3answers
137 views

Trigger Monostable 555 When Capacitor Raises above 0.5 Volts

So I want to trigger a monostable 555 to fire when a capacitor raises above 0.5 volts. My plan was to use a Zener diode to bias an NPN transistor that would trigger the 555. But I discovered the ...
7
votes
1answer
451 views

Understanding a high voltage generator circuit

I found a thread in the forum about a high voltage power supply 3V to 500V DC converter and someone suggested a circuit from techlib H.V. generator for Geiger tubes: However,when I tried to ...
1
vote
1answer
145 views

Zener doesn't seem to be working

So I'm trying to use a zener diode to limit the voltage across a capacitor - specifically, to 2.2V. As you can see, I'm using a 9v supply. The zener is in series with a resistor - either 100 or ...
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3answers
302 views

Charging a low-voltage high-C capacitor. Efficiently

I'm currently upgrading my wind-up torch - upon opening it, I found the manufacturers had been quite sneaky in that the circuit is EITHER windup OR battery powered - worse, the batteries are ...
-1
votes
1answer
260 views

non-inverting schmitt trigger op amp - replacing a zener diode on the input

I wonder if it is possible to replace the second figure below with the first one? Would both Vo output be the same on the figures below? If they are different, ...
1
vote
4answers
589 views

Transistor and zener diode

I have found this schematic and am confused about the transistor and the diode. I know that the phone voltage is around 3V and the PIC voltage is 5v, and it's a level shifting circuit. My questions ...
1
vote
1answer
177 views

LiPo discharge circuit doesn't work

A friend of mine gave me this circuit to discharge a 3V7, 5000mAh single-cell LiPoly accu: simulate this circuit – Schematic created using CircuitLab The zener is to make sure that the ...
7
votes
2answers
343 views

What's the equivalent zener voltage of two parallel zeners?

Assume we have two zeners connected in parallel, one with a zener voltage of x volts, and one with a zener voltage of y volts. What will be the equivalent zener voltage of the circuit?
2
votes
2answers
169 views

Why doesn't this (adapted) circuit work with the given power voltage?

I'm helping a little friend with his first project: an electronic dice from Velleman. The circuit is here (click to enlarge): He built it, I checked and improved it, everything was okay - except we ...
4
votes
1answer
110 views

Does the line on a zener diode correspond with the line in the symbol?

For a normal diode, the thin line on the component corresponds with the line of the symbol. Is this the same for a zener diode?