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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Simple overvoltage protection

I'm looking at a very simple method for overvoltage protection of a load connected to a standard external switching power supply. The load is powered by a 12V power supply, but this could be mistaken ...
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3.3v Zener Diode as Clamp not working

I have been trying to use a zener diode and cannot get it to work as expected. I have been searching forums and watching youtube videos without any luck, so hoping someone can explain it to me I want ...
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Mosfet Vgs protection

If I have a P-channel mosfet and I want it to operate with Vgs much more than absolute maximum ratings what's the best solution which can I do? I thought that a zener between gate and source might be ...
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395 views

Do I need buffers prior to a comparator?

I have the following circuit which generates digital noise... The reason for the 2 diodes has to do with stochastic uniformity of the noise output and I don't really want address this aspect. The ...
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Zener Diode at Base of Transistor [closed]

simulate this circuit – Schematic created using CircuitLab I am building a so called protection section for my mini project which involves a 3.9V zener diode parallel to a battery as a shunt ...
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388 views

What is the rating current of zener 1N702

I'm trying to solve a problem which requires the rating current of this diode 1N702. In the book, the author uses 1N961 zener for the examples and states that the rating current \$I_z = 12.5\$mA. In ...
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Load resistance determination in Zener Diode

Design a Zener regulator, regulated power supply using a 12V zener diode. When source voltage range from 15V to 20V and the load current ranges from 20mA to 100mA. a. Determine proper choice of Ri b....
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Zener diodes in glass axial package - not inherently shielded from photoelectric effect?

I discovered today that a glass packaged axial leaded 5V Zener diode will become a source of about 0.450 Volts when the glass package is held in the beam of a low-power purple (405nm) laser pointer. ...
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Zener voltage is not stable

i have a made transformer less power supply to power a arduino board and and two relays. The circuit is designed to get 6v and a current of 150mA. after building the circuit i have connected one ...
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151 views

Zener diode level conversion of tristate output

I have an MCP73831 li-ion charger connected to an ATMega1284p. The charger has a tri-state status pin which can be High(5V), Hi-Z or Low. The ATMega runs at 3V3. I want to be able to read the value ...
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How to get a +15v&-15v DC from variable AC source using Full-wave rectifier? [closed]

How to get to DC voltages (+15v & -15v) by using Full-wave rectifier, and if I change the AC source, the output stay stable, i.e Independent on AC source... any help? ..... I want to change AC ...
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159 views

How zener diode regulates voltage [duplicate]

I don't understand how a zener diode placed in series with a resistor creates a constant voltage for a load in parallel with the diode. The load voltage drop must be the same as the zener diode ...
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129 views

Switchable regulator with a Zener diode

I'm trying to develop a switchable 5v/3.3v power supply. I've got a switching 5V regulator that will drive my 3.3v rail. I've looked into using an LDO, and I think I'm going to go that route after ...
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612 views

24V to optocopler (voltage drop of 22.8V)

I have to detect a signal of 24V. The lenght of the signal is 1 second. So I use an optocopler. The led inside the optocopler must receive 1.2V. First I use a resistor (4k7) but the resistor heat ...
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Will this laptop charger work?

My laptop adapter just broke out, so I decided to make a simple adapter of my own but I would like someone to check the circuit diagram and tell me if it would work or not??
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Zener Diode Overvoltage Protection

a busy cat http://www.learningaboutelectronics.com/images/Overvoltage-protection-circuit-schematic.png Design Operating Characteristics Current Draw: 2 amps Operating Voltage: 13.5 V This design ...
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Zener Diode maximum current calculation based on max rated Power dissapation

Question as in picture part 3 a) Do I calculate the maximum current based of the slope resistance of 1 ohm and Pmax 3W (I squared R) Or do I calculate the the maximum current based on the 15V zener ...
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880 views

Why use a Zener in a regulator as opposed to a regular diode?

If you had a regular diode with a turn-on voltage of 5V (hypothetically), and a Zener diode with a reverse-bias of 5V, would the Zener diode still be preferred in a voltage regulator? I'm trying to ...
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274 views

Setting maximum opamp input voltage by zener diodes with respect to supply voltage

When I was about to implement a circuit with a 24V supply voltage I noticed that the comparator's inverting input in the part below receiving 24V with respect to ground when the input signal goes high....
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How to select series resistor for a Zener Diode

I have to simulate the reverse bias curve in Multi Sim with a 1N4681 I understood the equation to work out the series resistor to be: $$R_s = \frac{V_S-V_Z}{I_Z}$$ Which in my case would create a ...
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Simple Zener diode circuit for UVLO

Please see this circuit attached in this post/. Basically, I want to build a simple UVLO CCT for my LED controller and I came up with this circuit. simulate this circuit – Schematic created ...
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631 views

A zener diode versus a linear regulator for a 5 V 100 mA output

I have a 12 V supply and wish to use it to provide 5 V supply to NodeMCU, which draws about 110 mA. Which would be better to use? A 5 V 1 W zener and a 70 ohm resistor? Together they cost about $0.10 ...
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855 views

Hall Effect Sensor to a +24VDC PLC Input

I have a square wave from a hall effect sensor giving between UL 7.7v-8.7v to UH 11.3v to 12.7v from a 13V Supply. I need to pass this into a logic input on a controller which is nominally 24vdc but ...
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648 views

Electromagnetic Brake Control Circuit

I am troubleshooting a servo motor that is running while the brake is on when it shouldn't be. I have traced the control circuit for the brake as far back as made sense to. The brake is on a Panasonic ...
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Microcontroller input conditioning

I have the following circuit to condition signals reaching my microcontroller's pins. This circuit reads both digital signals in the range 0 to 30V, and analog signals in the range 0 to 3.3V. ...
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Determining power and resistor values for a zener voltage regulator [duplicate]

Above is a zener diode circuit used for voltage regulation. In Art or Electronics textbook theres a following exercise about choosing the right zener: Always Vz = Vout and 10mA is the zener ...
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534 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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189 views

Zener resistor configuration

Recalling this question: Choosing series resistors for zener diodes I thought to open a new question related to this, because it is centered to a specific part of the old question. It is said that, ...
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How to quickly distinguish DO-35 Switching diodes and Zener diodes

I do not have a magnifier glass handy. And many a times I saw Diode Numbers get wiped out after reusing the diodes. Is there an easy way to distinguish between DO-35 packaged Switching diodes like the ...
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Is there a passive component able to stabilize current (as zeners can do with voltage)?

So I need a component which will have a flat сurrent–voltage characteristic (constant current in a wide voltage range). Initially I was intended to ask a general question: what kind of the device can ...
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401 views

Zener diode selection in a led boost ic circuit

I'm wondering how to select a correct zener diode value for this led driver I am using RT4533AGJ6 (link to datasheet). My understanding of boost converters is limited, although I understand that there ...
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598 views

Characteristics of built-in Zener protection on FET gates

A lot of SOT-23 FET gates have built-in back-to-back Zener diodes to source, presumably to protect against over-voltage. However, the datasheets typically say nothing about the characteristics of ...
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how does this power supply work?

I was reading the datasheet for the LT1161, and dicovered the below construction in an example application toward the end of the document (Page 11). It appeared to be powering some Logic ICs. This ...
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SLA Battery warning circuit

I'm looking for a simple circuit to light an LED when a SLA's voltage gets below ~11.5 or some preset value. I found this one online but am having trouble understanding it. Nor does it function as it ...
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Small solar panel + ultracapacitor + zener

I am buliding a very small and low power "intermittent" sensor, powered by a tiny solar panel and an ultracapacitor. It works with a voltage from 1.9V to 3.3V, but the transmitted radio range greatly ...
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When considering Zener current, is lower current generally better?

I'm creating a small assortment for my parts box, and I wonder about Zener currents. For example, a selection of 4.7V 500mW Zeners spans a wide range of Zener current values: BZX79C4V7 = 5 mA Zener ...
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Investigate methods for analog Input Overvolatge fault protection

I have 8 analog input coming from various 5v and 3.3v sensors that have to be interfaced to a 3.3v micro-controller. The main system voltage is 24v-48v , i need to protect the ADC inputs against over-...
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“A zener with series diode”?

So I'm still reading The Art of Electronics Third Edition. On P.39, when dealing with indicative "kick", I found this sentence: For the fastest decay with a given maximum voltage, a zener with ...
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Limiting resistor for zener voltage regulator driven by transistor

I have this circuit: simulate this circuit – Schematic created using CircuitLab And I would like to understand why I need a limiting resistor for the current flowing through D1. I know the ...
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What decides the response time parameter requirement for zener diode

Assuming that a zener diode is being used to prevent over voltage condition from destroying an electronic component; how does the designer know what range of response time is required when choosing ...
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With limited components, how do I emulate a reverse-biased zener diode?

I understand that reverse-biased zener diodes don't conduct at all until they've reached a certain breakdown voltage, after which their voltage drop remains constant. I want to use this property in a ...
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What use is a Zener diode's leakage current spec?

Consider this datasheet for a family of Zener diodes. All of the parts 3V and under have their leakage current rated as some current at 1V. I've seen this is multiple family datasheets, but it really ...
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How do zener diodes regulate voltage? [duplicate]

So i read about the Zener diode voltage regulator circuit in the The Art of Electronics book, it made no sense to me, then I read about it in this article which was ...
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Can I achieve debounce using a zener diode?

I am interfacing a 4x3 keypad with LPC1778 using GPIO pins. These pins are 5V tolerant. Can I use zener diodes in the debouncing circuit? Can I use zener diodes like this?
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Rationale for operating the diode in the (reverse biased) breakdown region

For the circuits I've studied thus far involving diodes (which admittedly are not that many), they have been nominally used in the forward-bias mode. For example, the LED only lights up when it's ...
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918 views

Why is the voltage across a Zener diode so dependent on current?

I was going to use a 3.3V Zener diode to protect the analog inputs of an Arduino Due, but I found that the voltage drop across it was only 2V. So I tested connecting it to my power source with a ...
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Which circuit best approximates a zener diode?

Above on the left side is the original zener diode circuit. I want to draw an approximation of this circuit, given the zener voltage Vz and zener resistance Rz (Rz is considered constant for ...
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Obtaining dynamic resistance of a zener diode in LTspice

Please left-click to enlarge Above is a circuit where: D1 is a 10V(breakdown) zener diode, V1 is a voltage source which varies from 11V to 5OV DC and R1 is a 1k resistor. My aim is to identify the ...
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775 views

Square wave at line frequency. How does it work?

I found the following circuit next to a switching power supply in an electrophysiology amplifier (AXOPATCH 200A, an instrument for a technique called "patch clamp"). References to power outlet: L: ...
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Replacing zener diode with a resistor in current limiter circuit

Can we use a resistor to replace the zener diode in this current limiting circuit ? Why do you think using a simple resistance is not enough to trigger the base ?