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63 views

Spark Suppressor Question

I built a timer for my water heater and have a question about spark suppression. I am using a 120v house timer 1875W to operate a Packard (240B) 2 pole 40A 120v coil relay. The output of the relay ...
1
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2answers
58 views

Ethernet surge and protection

I recently worked with a client who experienced a transient on their Ethernet cabling. As you can see, no actual PCs were damaged, only the Ethernet cards of some machines. We don't know where the ...
4
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1answer
143 views

Clamping Inductive Kickback in AC Circuits

I want to eliminate/clamp the inductive kickback that would result from turning off a large inductor, such as a relay or a transformer. In a DC circuit, I would use a diode to flywheel the current. ...
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0answers
45 views

Why would you use both Varistors, TVS diodes in the design?

A similar question has been asked but not really answered here. For transients occurring in class-2 AC powered devices, why would an MOV or just a TVS not be enough and most design include both?
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1answer
98 views

Correct design for large contactor circuit?

After some advice here I'm wondering if this is the correct design of my circuit. I'm now using a SSR as the control device to the contactor. The diode, I believe, should not only protect the SSR ...
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0answers
42 views

Overcoming the voltage gap between a TVS diode's reverse stand off voltage and max clamping voltage

Consider the following scenario (all values are just for example): A device has a max input voltage of 9V and has components where the absolute maximum voltage is 15V. In order to protect against ...
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1answer
73 views

Does this Schottky provide MOSFET transient protection?

I'm studying the schematic for an electronic load available as a kit from Jameco: http://www.jameco.com/Jameco/Products/ProdDS/2161107%20Schematic.pdf There is a Schottky diode shunting the ...
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3answers
209 views

Why do designers use a series diode and zener for coil suppression rather than just a zener?

I understand the use of the Zener but what I don't understand is one topology uses two components, but why can't the other topology be used ? simulate this circuit – Schematic created ...
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1answer
181 views

How do I model an over voltage spike on LTSpice? Any circuit example

I am doing project, I am trying to simulate an overvoltage/under voltage protection controller on LTSpice. How do I create overvoltage/unudervoltage on a source? For example a transient voltage spike? ...
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2answers
101 views

Are all snubbers interchangeale?

There are different kinds of snubbers that can be used. I know of 3, but there could be more. D RC RCD If an certain circuit uses a diode, can I swap it for an RC ? Or if a circuit has an RC, can ...
2
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1answer
558 views

How to conduct “Transient Power” measurement according to ETSI EN 300 220-1 (v2.4.1)?

Background Info The company I work for builds Active RFID hardware that needs to conform to the regulations defined in ETSI EN 300 220 (Part 1). Our working frequency is 433.92 MHz. I am responsible ...
2
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1answer
181 views

Is a 9.6µs over-voltage transient long enough to fry my circuit (Details inside)?

I am designing a board for a 12V automotive environment, with a variety of input voltage transients including load dump and permanent 24V over-voltage. I am using a TVS at the input to clamp to around ...
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2answers
712 views

Transient voltage suppression diode not doing its job

I have a circuit which works on 21V DC and draws 3A maximum current. I need to get it tested to IEC 61000-4-4 and 61000-4-5 standards which are surge immunity tests. I use a UL certified switch mode ...
3
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3answers
281 views

TVS specification understanding

I have some questions regarding Transient Voltage Suppressors (TVS). The specific datasheet I'm referring to is this, from 1SMB22AT3G. Here is some of its specs: \$V = 22V\$ \$V_c = 35.5V\$ ...
3
votes
2answers
632 views

How to suppress current spikes in transistor feedback loop

I am trying to pulse a load with a small constant current pulse (2mA @ 500us). The load does unfortunately have an unknown capacitance in the range 10nF - 1uF, parallel with an unknown resistance ...
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2answers
201 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
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2answers
626 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 ...
5
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1answer
237 views

Current-sense for NES/SNES gamepad detection - getting a voltage spike

I'm in the process of designing a wireless controller receiver for the NES/SNES game consoles. My wireless receiver consists of a bluetooth module and an AVR microcontroller, with the microcontroller ...
4
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2answers
401 views

Regarding ESD diode's architecture

I need one clarification regarding ESD,EFT and SUrge protectors. Different manufacturers have architectures of diodes+Zenar diode combinations for different protection levels for different interfaces. ...
1
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2answers
478 views

Varistor S10K30 for 24-40VDC input?

I was put in charge of redesigning a motor control circuit which accepts 24-40V DC on its input. As a side note: As far as i know, the existing circuit has been working fine for several years. The ...
7
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1answer
632 views

Help tame turn-on transient

I'm working on a dual headphone amplifier. I've discovered that it has a pretty bad turn-on transient that results in a loud pop if headphones are plugged into the amplifier when it is turned on. ...
5
votes
3answers
1k views

How to properly snub transient spikes from a transformer and prevent switch mode power supply burn out

I've received a failed switch-mode DC-DC step down converter (part# LTC3631 from Linear). This circuit was driven by a 24VAC transformer which is rectified on the circuit: simulate this ...
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2answers
4k views

How to decide between a TVS or Zener diode for overvoltage protection?

I'll leave my specific circuit out of this for a more broad question: What criteria does one use when deciding whether to use a Zener diode or a transient voltage suppressor, for overvoltage ...
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2answers
4k views

What are bidirectional Zener diodes used for in DC transient protection?

I often see two zeners (in opposition to each other) being placed across the power supply rails. I don't understand why that is necessary. For example, if I have a 16V Zener diode and a 12V power ...
9
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2answers
2k views

Flyback diodes issues and pull-in & hold current issues in this Relay circuit

Although this may be a basic question but I'm still struggling with it. In this schematic, two zener diodes D1 and D2 are connected back-to back across relay coil L1. The BVds = -30V for Q1. Can I use ...
4
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1answer
174 views

How does a high voltage condition break down a semiconductor?

I have TVS diode in parallel with circuitry for ESD/lightening/transient voltage protection. Say I receive an over-voltage condition which is beyond the specifications of the part, what happens ...
4
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2answers
2k views

Long supply line and capacitor to prevent voltage drop

I have a 30 feet line with DC supply 12 V. A motor on the end draws about 0.5 Amps initially (100 ms). It's logic shuts down because of the line's voltage drop caused by inrush current. A capacitor of ...
16
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3answers
8k views

How to limit inrush current?

I'm designing a device powered from USB. The device uses FTDI FT2232 chip for USB connection. Upon a command from a computer FT2232 chip should enable power via a MOSFET switch to rest of the circuit. ...
3
votes
2answers
363 views

Are transient suppression diodes necessary for a battery powered system?

I've seen on designs where there is a TVS transient suppression diode on the voltage supply. For example, when the voltage supply is say a wall plug. However, are such diodes really necessary in a ...