Questions tagged [varistor]

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ZNR rating difference between original and replacement PCB

I have a defective AC PCB and its potential replacement. The PCBs are near identical: same voltage zone, same micro controller... except the rating of their 4 ZNR components (surge protection) The ...
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1 answer
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I need help Identifying these two varistors

I need assistance in ordering replacement varistors for the light dimmer switch in my 1998 Nissan Frontier. These are from 2 different switches which have exact part numbers, but the varistors are ...
-1 votes
1 answer
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What is the function of varistor in this design [closed]

Came across this on internet. The description mentioned this module help prevent relay stick to the contact. Please explain why varistor need to be included in the design if it is to connect in ...
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2 votes
2 answers
267 views

Help identifying MOV

Need some help in Identifying MOV ZNR E14221 RU068
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5 answers
175 views

Can I use a normal diode as a Zener/Varistor ? If not, why not? (focus on Varistor use)

When I look at a normal diode graph like that I see the Vz Zener voltage of it looks just like a Zener, so why not using it reverse biased like a Zener? I ask like that because I never saw it being ...
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1 answer
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Confused about back EMF protection in maglock circuit

Straight upfront...electrical engineering is not my forte. However, I am trying to help a client with a particular issue and I'm hoping this community can provide some invaluable insight. They have a ...
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0 answers
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Noise suppression circuits for a 120VAC motor

I am building a circuit for a relay that controls power to a 1000 watt pump motor. I want to do what I can to reduce noise and failure of the circuits from transients etc. Here is my schematic: I ...
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0 answers
62 views

Trying to ID component

Anyone recognize this component or have a NSN or part number? On the back it says: 0Q6Q MEXICO
1 vote
1 answer
117 views

Can placing MOVs on an 240v input be ever a bad thing?

The power supply of my home lighting keeps failing. So far i have 10 of the same power supply failed. Upon inspection the thing that is always get damaged is the Electrolytic Capacitor after the ...
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3 answers
146 views

PWM output to adjust voltage

I am trying to create a dimming system for this set of 10 leds, using an output from an ESP32. This is what I came up with: Using a 20 volt power supply going through a variable resistor which ...
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1 vote
2 answers
209 views

AC input safety and filtering: MOV and class X/Y capacitor

Is there a design practice for having both a varistor and a class X or Y capacitor for safety and voltage transient protection on AC circuits? At my work, a previous employee designed a simple AC to ...
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2 answers
150 views

Crack in surface of varistor, likely bad?

I experienced a power surge at my house and some equipment stopped working. one device just had a blown fuse so I soldered in a new one and it worked fine. Another device had an obviously blown ...
1 vote
1 answer
236 views

Component identification - Power supply circuit component exploded

I am fixing the power supply board of a big mobile sound system. Skytec PA-200 - sadly I could not find any schematics or more information on it. Unfortunately not only an electrolyte capacitor but ...
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-1 votes
1 answer
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Choose a varistor for a broken PC PSU [closed]

My computer's PSU (Corsair RM 650X) has blown. I've searched a bit online and I have found that this is a common defect due to a low quality varistor put in those kind of PSUs before 2018. I know this ...
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1 answer
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Help identifying a varistor from a fluorescent light tube ballast

I am trying to identify the blown varistor from my fluorescent light tube when I was trying to fix it. I have never seen a manufacturer marking logo on it with a "W" and a cross in the ...
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2 answers
331 views

Electric stove heating element and switches

I am having difficulty in understanding how heating elements and switches work to control how much heat is dissipated in the element of electric stoves or other similar settings. From one perspective ...
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1 vote
1 answer
153 views

Can I use a back to back Zener as a flyback diode for an AC coil?

I am using the below AC electromagnet to switch on/off a pneumatic system. (It is a pneumatic actuator. I think that is what it is called.) The issue is, when I turn off (disconnect the switch) the ...
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2 answers
226 views

Help Needed to Identify/Source Varistor S14 K140 0023

Could someone please advise on how I interprate the codes on this Varistor below.. I'm almost there, I can find the S14 / K140 on RS Components, But im unsure about the last 4 digits. RS Website PN:...
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1 answer
70 views

Help Identifying a Component (Varistor)

I am trying to identify the component (I believe is a varistor) in the image below (is from a blender). In another piece of the epoxy I was able to read 14. Should I assume is a 14d241K? Tks! Lino
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2 answers
260 views

Varistor equivalent

I am repairing an old Marantz stereo amplifier and have come across a varistor MV11Y that appears to be the issue. Is anyone able to advise/send me the data sheet for this varistor or perhaps let me ...
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1 answer
133 views

Help identifying a varistor (on a shredder PCB)?

I am trying to identify what I think is a varistor. The markings are : "9 / MVG" and "10K431". I think "10" is the diameter, "K" is the tolerance and "431&...
1 vote
0 answers
296 views

Replacement for TVR 10561 varistor

I am trying to repair the power supply of my PS4. It looks like the fuse has blown out with the TVR 10561 varistor. I can't find this varistor online and I am looking for a replacement. The TVR 10561 ...
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0 answers
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Dynamic voltage balancing in series-connected varistors

I have several varistors (of type MOV-14DxxxK) in series connection. Voltage balancing is very good when applying DC voltage. Does anybody know if there would occur problems concerning dynamic voltage ...
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2 votes
1 answer
345 views

Suitable Substitute for this Varistor MDC Z750 / 40

I am in the process of restoring a vintage EZGO Golf Cart and have came across a component I am unable to locate within the generic golf cart electrical diagram. This varistor is from a 36 volt DC ...
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1 answer
158 views

Is this a capacitor or a varistor? How can I figure out specifics?

Is this a capacitor or a varistor? How can I figure out specifics?
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1 answer
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Transient current value

I am working on a SMPS and wanted to size a varistor at the input to protect the rectifier against transient overvoltage (let's say a 1 ms surge). However, by looking at datasheets the maximum ...
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1 vote
1 answer
567 views

Is this a varistor? WP 270M

I can't figure out whether it's a varistor or any other non-polar capacitor. Please also suggest how to test it.
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1 vote
1 answer
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Protecting a switching regulator in a 12v automotive system

I'm using a MaxLinear XRP7659 as a 12v -> 5v regulator in my design. The circuit has an average power usage of 80mA @ 12v and a maximum usage of ~500mA @ 12v. I have a 750mA fuse on VIN, along with ...
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2 votes
1 answer
735 views

Varistors in three phase application

From this Reference Design, I have the following inquiry: Usually in three phase applications I see varistors connected between phase to phase, or between phase to ground. In the reference design, the ...
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0 votes
2 answers
343 views

Varistor and TVS diodes in series

In the picture below, the input of the rectifier is 690VAC max, so the DC output can reach up to 1kVDC. The DC output goes to a low power DC/DC Converter. In the picture on the left, I'm using a ...
user avatar
1 vote
2 answers
289 views

Why would bridging a varistor with the multimeter leads on any setting have caused the unit to turn on?

So I've been working on fixing this window AC unit for a while, and when I started I knew next to nothing about circuits. At present today, I know a bit about circuits -- enough that i at least know ...
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1 answer
979 views

Do I need to remove the varistor from the circuit to check its validity with DMM?

When I looked up how to measure varistors, I found that the varistor's value should be 0L ohms (Over range, infinite resistance) when measured by a DMM set to test resistance, to indicate its validity....
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1 answer
101 views

Identify a varistor

I'm trying to replace these two varistors from my maytag dryer. I'm not quite sure what party they are. They look like epcos/tdk brand but not sure what the s20 k275 11 08 means, Or the other symbols. ...
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1 vote
2 answers
265 views

Varistor - Place before or after the fuse? [duplicate]

What is safer? Before or after the fuse? In my case the varistor is 10mm, 275Vrms, and it is currently placed after a 250Vac, 7A, 20mm glass fuse. Would the varistor blow the fuse easily if placed ...
-1 votes
1 answer
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Why does the high capacitance of a metal oxide varistor affect sensors and signal sensitivity?

I want to know why the high capacitance of metal oxide varistors affects sensors, signal sensitivity. How does capacitance affect sensitivity ? If we add a low capacitor in series will the total ...
1 vote
0 answers
80 views

Can we use tvs and mov together for thruster?

I want to know if we can use both tvs and mov varistor together ? What will be good for thrusters ? And placement between esc and thruster or before esc? Update: system voltage is power supply ...
1 vote
1 answer
2k views

Why often is used a varistor 7D471K for 220-240vac surge protection rather than a lower nominal voltage one?

In my "supposedly" surge protected power stripe there is a varistor for surge protection configured to simply short-circuit the entrance wires in case of surge. Checking the model it's a MOV-7D471K ...
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1 answer
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Varistor in a DC circuit

I'm employing a Varistor in a simple circuit that will be used in a car. The Varistor is there to ensure that any load dumps / vehicle transients will not result in catastrophe for the circuit. My ...
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1 answer
677 views

Calculation of varistor parameters for AC line protection

There is a task to choose a varistor to protect the AC circuit, controlling several coils of magnetic starters. Characteristics: Mains voltage 230-240V AC Frequency: 50Hz Starting current of coils ...
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1 vote
1 answer
195 views

Identify unknown disc-shaped component - markings include VF10 0471K

I am trying to identify this piece, which I believe is a varistor, though I'm not sure. It comes from a Samsung rice cooker. I have attempted numerous google searches on the markings, but I have so ...
3 votes
1 answer
732 views

Are external components required for HLK-PM01?

Apologies in advanced as this is kind of a vague question and due to my lack knowledge in this specific sector. I'm designing a circuit using a HLK-PM01 as the power supply which is a 3W AC-DC ...
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1 vote
2 answers
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Placement of varistor with respect to fuse

My design includes a pretty standard AC/DC converter powered by mains for intended use at home. For overvoltage and overcurrent protection, I am planning to use a combination of varistor and fuse ...
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1 answer
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Trying to ID this component & where to get a couple of them? Is it a varistor?

Here's a photo I made to show back and front of this thing. I think it's a varistor. The main body is roughly 8.5mm in diameter. I straightened the two legs but I think they are SUPPOSED to have ...
0 votes
1 answer
54 views

Need some help Identify a Varistor

I had a either a surge or a part failure cook a few components on board. The board is rather old from a discontinued product. On the board the only components I've not been able to identify that need ...
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17 votes
3 answers
2k views

Varistor? Purpose and principle

In the AL9910 LED driver datasheet it shows a part, which I assume is a varistor, is it so? Varistors are shown to be connected across L and N lines, but here it is connected in series. Please explain ...
3 votes
1 answer
578 views

Creating a temperature-dependent solar cell in LTSpice (using varistors)

I'm currently working on my master thesis and therefore need to simulate a solar cell in LTSpice. I've already modeled and simulated some examples with constant values. But for a more accurate model, ...
2 votes
2 answers
226 views

How much buffer room is required for a varistor?

I am working on a circuit board design that uses a fuse resistor for protecting from short circuits and a varistor to protect from over voltage. The board is a simple power supply of only a few watts. ...
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1 answer
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What is this solar power RC circuit doing?

I am a CSE student working on a project. We are using a solar powered microcontroller. The solar panel's power goes through a fuse and an RC circuit with a varistor to the charging system. What ...
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1 answer
1k views

Why does my varistor cause my fuse to blew up?

I have made the following circuit (copied from a very similar picture on internet): At one side of AC/DC I put a normal fuse. The MOV is a 14D391K 14K391 390V varistor diameter 14mm AC 250V DC 320V ...
5 votes
2 answers
5k 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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