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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1answer
230 views

Noise generator with LM318

I want to build a noise generator from a Zener diode. I designed the above circuit. The noisy voltage from the diode is filtered via a high-pass filter and input into a 92x gain non-inverting ...
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1answer
45 views

Powering a low current device from a mosfet N

I have a question regarding a circuit providing low current capacity voltage for device powering, that goes down from a lot higher voltage: How does it exactly work? I understand that the Q1 gate is ...
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106 views

P-Mos switch high side

I'm trying to switch P-Mos given that: Vcc > Vgs max Enable_output is 0V or 3V I'm switching both GND and VCC on purpose. 4. 8.4VR at 2uA ! The questions: When Q2 is off, what is Vgs at Qsp1? Is ...
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7answers
2k views

Calculating the voltage drop of two Zener diodes in series? (reverse conducting)

I'm building a circuit powered from a 12V 55mAh (A23 battery). Needless to say that power consumption is a primary concern. The circuit is an ATtiny85 which is driving 13 LED's (in 5 groups). I ...
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2answers
261 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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5answers
216 views

Does a transistor work by connecting the collector to emitter? If so, why do transistor regulators work?

I am wondering why a transistor, such as one used in this Zener diode + Transistor regulator , has the output controlled by the base voltage rather than the collector. My textbook (which has this ...
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1answer
258 views

How does this Current Comparator Circuit Work?

I have a quick couple of questions about this circuit: The schottky diodes are obviously for minimizing slew delay but how exactly do they do this? If the non inverting input is tied to ground and ...
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1answer
76 views

PSPICE graphs work separately for subcircuits, wrong when combined?

I'm working on a pulse generation circuit that will be used to drive an ultrasonic transducer. The following circuit is giving an unexpected output. It might look complicated, but really it can be ...
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1answer
61 views

High side driver internal design

I have a question about the high side driver VN7016AJ for automotive applications, during ISO pulse1 -150 V will be applied at its VCC pin, I found from the User manual (UM1922) that when -150 V is ...
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1answer
502 views

What is a typical reverse recovery time for a zener diode, or is reverse recovery time not applicable to zener diodes?

A little background.. I'm trying to understand how zener diodes respond to high voltage transients. I stumbled across discussions of reverse recovery time and I'm curious how it applies specifically ...
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409 views

How can I create voltmeter with Zener diodes?

simulate this circuit – Schematic created using CircuitLab 5 LEDS One LED is to remain always on when current is passed through. One LED will turn on when voltage is between 50 to 90 volts. ...
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3answers
136 views

High voltage to low voltage in ps/nanosecond time (Zener/opamp?)

So I have a signal that goes from 0 to ~800volts in 30ns. I would like to use this signal to trigger a camera (input impedance of 50ohm) which takes a max of 10 volts and requires the rise time to be ...
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1answer
1k 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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65 views

Zener Shunt Regulator Question

I want an alternative low component, transformerless power supply for low power DC projects, I have used Shunt Regulators in the past but never with AC. Below I have proposed a AC to DC shunt type ...
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2answers
625 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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157 views

Using a zener diode and a bjt to regulate voltage received by a controller

Okay, here goes… I’m trying to create a circuit that will prevent low conductance (from rain water exposure) which occasionally shorts a particular switch, from triggering a controller input that the ...
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2answers
2k views

How can I compare a TVS diode with a varistor?

For a 120Vac line protection element, comparing this TVS diode: With this varistor: The immediate differences I see are: The varistor is marginally cheaper The varistor specifies a maximum working ...
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2answers
217 views

3.3v Zener Diode Shunt Voltage Regulator giving a 4.3v output

We are trying to use a zener diode shunt circuit to develop a voltage regulator. Our input voltage is 5v. Our desired output voltage is ...
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1answer
363 views

Zener diode at inverter op amp's output

I would like to know what would be the effect of placing a Zener diode between the op amp's output and the actual output of the circuit like shown in the schematic. The Zener should be of 5 V. ...
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531 views

Protecting against over voltage but with minimum leakage current

I have a circuit where I sense an input which is a voltage divider with resistor. Since the voltage divider needs to have high impedance, the current flowing through is in the range of 10's of uA. I ...
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1answer
158 views

Why is Zener reverse based on relay circuit?

In a common relay circuit a zener diode, or other diode, is used to shunt the spiked that the relay could cause. Now, why is the zener's cathode connected to the battery (or other source)'s positive ...
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1answer
139 views

Using a voltage divider with buried zener voltage reference

My plan in the below circuit was to use a voltage divider from a Max6225 2.5Vref, to get 2V and 1V from it in order to use the full 16bit bipolar scale of the ADS1115s, but I'm getting strange ...
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1answer
2k views

Create a blinking LED circuit with a z-diode and a capacitor

I was searching for the most simple LED flashing circuit. On a webpage (http://cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html) I found the following circuit with a transistor ...
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1answer
133 views

Schematic for input protection with NMOS? Does this really work?

I was reading an old schematic and found this and sketched it up; (see box in image "Some kind of protection") The closest thing to this schematic that I've been able to find, that could have briefly ...
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2answers
2k views

What is a simple voltage limiting circuit?

I am searching for a neat solution for an input voltage limiting circuit. Situation: I have a circuit with an input voltage range from 6 V to 20 V at 3 A peak (the load), however my source can be ...
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1answer
189 views

Lead acid battery charging current dosent become zero

Here I am charging a 6V 4.5Ah lead acid battery by using a 8V-10V LM317 input supply for the circuit. I'm using the BD139 transistor to cut off and a 6.8V zener diode. As the battery voltage reaches ...
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1answer
85 views

High Side Driver IC - Application Information

I have a question regarding VN5025AJ-E: High side driver IC. Datasheet link - https://www.st.com/resource/en/datasheet/vn5025aj-e.pdf In the figure you can see the application schematic. In the ...
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3answers
132 views

1N4728 Zener behavior

Here I have the image of a signal in the output of U2, and the output is shown in green in the graph(sorry for the poor quality). Highest value = 3.3V, Lowest value = 0V, sine wave, 60 Hz. Now I have ...
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2answers
644 views

What's the cheapest way to make a dithered-input ADC?

I know that some of these PICs have ADCs built in, and I may want to use that. I am wondering if there is a way I can effectively dither the input to a low-bit (like 8 bits) ADC with the fewest parts ...
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2answers
316 views

Charge 5,4V supercap with 12V solar panel

I'm building a circuit to charge a series of two supercap (500F, 2.7V each) with a solar panel (wich outputs, not sc, 18V@1.5A with direct sunlight at 12pm). Those supercap will then power an esp8266 ...
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2answers
337 views

Detect 230VAC or 12VDC in the same pin [closed]

I'm designing an input interface for a microcontroller (uC). Want to detect signals (only want to know if there is voltage or not) of different typology, so you can have in the same input to the board:...
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3answers
372 views

Prevent excess current through Zener regulator when system load is switched off

I use a hub-generator powered LED lighting system in my bicycle, made by myself using rectifier, capacitor, and Zener. It's working very well for many years, the Zener does not get hot, and the high-...
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2answers
840 views

Flip a Schmitt-Trigger when current flows through a Zener diode

I am trying to design a circuit using an intermitent power source (a bicycle hub generator), which is rectified and filtered, and regulated at 6,8V. Now I want to "detect" when the power source is ON ...
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2answers
273 views

Is this resistor necessary for protection?

I would like to incorporate this circuit in my design so that I could use a low current capacity slide switch to control the 2A current of a Li-poly. Now, I understand the purpose of having two PMOS ...
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1answer
923 views

Flyback diode is acting weird

I have the following schematic: Vcc can vary from 12 to 15 volts, so the design was intended to switch on the relay through a MOSFET when the input voltage is over 13.4 volts. The actual Zener I've ...
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1answer
87 views

I need some help to identify a few parts

I need some help to identify parts D2 and ZD3 in the photo below. I can't find anything for replacement using their markings which I believe are B704 and XF81, but I could be wrong.
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0answers
164 views

Use of DC source in Zener clamping circuit

A question in my engineering degree asked me to design a clamp circuit that gives a 10V 50Hz AC signal a +5V DC bias. I designed the following circuit as my answer: I assumed 0.6V forward drop for ...
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1answer
483 views

LM311P op-amp strange behavior in comparator mode

I'm trying to build a schematic which will turn on a relay in case motorbike battery voltage will reach some level. I've ended up with the following schematic. simulate this circuit – Schematic ...
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1answer
7k views

How can I use/model a custom diode in LTSpice?

I would like to simulate the behaviour of a zener diode in LTspice. Consider the following schematic simulate this circuit – Schematic created using CircuitLab I'm interested in simulating its ...
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1answer
259 views

Why is the zener voltage increasing with the load resistance in this circuit?

The circuit below is composed of an 8.2V Zener diode, an R2 series resistor and a load which is a variable resistor R1: The load resistance R1 is increasing from 1 Ohm to 2k Ohm. As the load ...
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1answer
1k 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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1answer
1k views

12V 12A resettable crowbar circuit

The idea is to protect the input stage of a control card from improper power supply connection. The power supply is a standard desktop AC-DC power adapter (Meanwell GST160A12) with inbuilt shortcut, ...
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2answers
191 views

Line regulation of zener diode with jfet

How am I able to calculate line regulation (S=dUout/dUin) for zener diode with current provided by JFET with zero gate - source voltage? Schematic below Lets say it's typical BF256B as JFET and BZX84-...
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1answer
62 views

Avoiding accidental earthing, voltage rejection, and voltage dividers for a motor control output circuit

I'm trying to connect up an integrated control DC motor with a 24V output (Motor manual - relevant page p32) with my 10V PLC (PLC Manual), and looking for a little help please. I don't understand why ...
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2answers
124 views

Transfer Function of Op Amp Circuit

How can I obtain the transfer function graph of this circuit, assuming the zener diodes voltage are 4.3V and silicon diodes 0.7V.
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1answer
327 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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0answers
68 views

LCD default boxes not showing when contrast pin is hooked to old-fashioned regulator circuit

I have an HD44780 compatible character LCD display (2 rows 16 characters a row) powered with 5v through a regulator (4.97V according to voltmeter). If I connect a 2.2K resistor between the LCD ...
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1answer
82 views

Solution for unconnected GPIO extender pin

I have a situation like the one below The GearN is either GND or not connected. I don't have control over those states (it's a motorcycle gearbox sensor). When the pin is not connected I reach 7.5V ...
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2answers
130 views

How to calculate properties of voltage regulation circuits [duplicate]

I have a few options of adding voltage regulation to my pcb circuit (the regulation is from 12V to 5V). The options are stataed in the figures below. My question is: How do I calculate the ...
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3answers
859 views

zener diode i-v confusion

So zener diodes in reverse bias apparently only work within a specific current, Is min and Is max which generally have basically the same X value. On the zener diode graph usually lets say Is min is ...

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