Best Diode Circuit Testers of 2026

Name: OBDResource Voltage Tester Car Circuit Tester, 0V-80V DC Car Voltage Tester with Power Circuit Probe Digital Screen for Testing Car Battery/Continuity/Grounding/Polarity/Diode/Lamp
Brand: OBDResource

Jennifer Fraser

Last Updated: 4 Feb 2026

* We independently evaluate all recommended products and services. If you click on links we provide, we may receive compensation.

Diode circuit testers are indispensable tools for hobbyists, electricians, and engineers. These testers are designed to check the functionality of diodes, which are electronic components that allow current to flow in one direction while blocking it in the other. Diode circuit testers can quickly and accurately determine whether a diode is working correctly or not, saving time and hassle in the troubleshooting process. With various models available on the market, diode circuit testers are a recommended addition to any toolkit.

At a Glance: Our Top Picks

#TOP 1

OBDResource Voltage Tester Car Circuit Tester, 0V-80V DC Car Voltage Tester with Power Circuit Probe Digital Screen for Testing Car Battery/Continuity/Grounding/Polarity/Diode/Lamp

9.8

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OBDResource Voltage Tester Car Circuit Tester, 0V-80V DC Car Voltage Tester with Power Circuit Probe Digital Screen for Testing Car Battery/Continuity/Grounding/Polarity/Diode/Lamp

#TOP1

9.8

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#TOP 2

KZYEE KM10 Car Power Circuit Probe Kit, 12V 24V Automotive Circuit Tester, AC DC Diode Resistance

9.7

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KZYEE KM10 Car Power Circuit Probe Kit, 12V 24V Automotive Circuit Tester, AC DC Diode Resistance

#TOP2

9.7

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#TOP 3

VKALTUL Circuit Tester BT250, Car Power Circuit Probe Kit with AC DC Voltage/Resistance/Diode Test

9.5

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VKALTUL Circuit Tester BT250, Car Power Circuit Probe Kit with AC DC Voltage/Resistance/Diode Test

#TOP3

9.5

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Top 10 Diode Circuit Testers

#TOP 1

OBDResource Voltage Tester Car Circuit Tester, 0V-80V DC Car Voltage Tester with Power Circuit Probe Digital Screen for Testing Car Battery/Continuity/Grounding/Polarity/Diode/Lamp

OBDResource

CP10

blue

CP10

OBDResource Voltage Tester Car Circuit Tester, 0V-80V DC Car Voltage Tester with Power Circuit Probe Digital Screen for Testing Car Battery/Continuity/Grounding/Polarity/Diode/Lamp

9.8

FTB Score

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Features

Brighter Headlights And Screen: The 2 Front Lights Can Illuminate Dark Place Of Your Car Once The Tester Is Connected To The Car Battery. Every Corner Of The Car Can Be Tested While The Length Of The Lead Is Up To 5 Metres. The Digital Acrylic Display And Polarity Indicator Allow You To Intuitively Determine The Status And Voltage Of The Test Lead. Not Only In The Dim Place, But Also In Direct Sunlight, The Data Can Be Read Clearly On The Screen.

Multi-Functional Car Voltage Tester: It Can Test Voltage And Polarity Of Battery, Continuity Of Car Circuit, Locate The Short Circuit, Components Of Car (lamp, Trail Light, Etc;) And The Grounding Condition. You Can Also Repair Or Inspect The Circuit With Jumper Operation. With This Instrument In Hand, You No Longer Have To Worry About Any Electrical Problems Of Car Circuits.You Can Keep It At Home To Quickly Check The Car's Wiring And Components.

Wide Applications: The Test Lamp Kfz Is Compatible For 0V-80V DC Voltage Environment, Which Can Test Circuit Or Components (Especially The Spark Plugs.) On Cars, Pickup Trucks, SUVs, Motorbikes, Construction Vehicles And Boats. If A Vehicle's Electrical System Fails, A Voltage Tester Can Be Used To Quickly Detect And Identify The Problem, Making It The Right Tool For Drivers To Always Have On Hand!

Quick Testing Of Components: With The Power Circuit Probe And Alligator Clip, You Can Control The Probe To Output A Positive Or Negative Voltage By Pressing The Button. So It Can Test Vehicle Components Such As Lamps Offline, Or To Test Components By Connecting Them To The Vehicle Wiring. The Automotive Voltage Tester Also Supports Jumper Operation, Which Can Jump Over The Original Line To Check Or Locate The Short Circuit.

Grounding Test And Buzzer: Some Components Require Good Grounding Of The Negative Iron Part, And A Voltage Tester Can Check The Integrity Of The Component Grounding. If The Grounding Is Good, The Buzzer Will Sound And The Polarity Indicator Will Turn Green, If The Grounding Is Bad, The Polarity Indicator Will Remain Red And The Buzzer Will Not Sound. The Buzzer Will Sound Whenever The Contact Negative Path Is Good.

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#TOP 2

KZYEE KM10 Car Power Circuit Probe Kit, 12V 24V Automotive Circuit Tester, AC DC Diode Resistance

KZYEE

KM10

Orange

KM10

KZYEE KM10 Car Power Circuit Probe Kit, 12V 24V Automotive Circuit Tester, AC DC Diode Resistance,Component Activation,Short/Ground/Continuity/Trailer Test,20FT+20FT Cable

9.7

FTB Score

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Features

[4 Modes Easy-To-Operate Diagnostic] The Circuit Probe Kit's 4 Modes Can Be Accessed By Simply Depressing The Mode Button. DC Voltage: Read The DC Voltage With A Resolution Of 0.1 Volts. AC Voltage: Read The Max. Voltage, The Min. Voltage, Frequency, And Duty Cycle. Resistance: Read The Resistance Between The Tip And Auxiliary Ground Lead. Tone On/Off: Technicians Use The Tone In A Dark Environment To Distinguish The Test Results And Turn It Off When Unnecessary.

[2026 Newer Version KM10 Automotive Circuit Probe] KZYEE Circuit Tester Is Most Accurate Power Circuit Probe Tester Yet, With 160x128 TFT Display Test All 6-30V Vehicle Electrical Systems. It Supports Voltage&Polarity TestContinuity TestSignal Circuit TestComponents ActivateCheck Bad GroundingLocate Short CircuitsShort-Circuit ProtectedCircuit Breaker Protection, Etc. Besides, KZYEE Power Circuit Tester Has Extra Long Cables, Itself With 20ft (6m) Plus Extra With 20ft (6m) Cable; Also Comes With A Cigarette Lighter Plug. Intuitive Interface With Ergonomic Design Makes It Be Best Gift For All Novice Drivers Or Pro Circuit Repairers.

[Packing List And 3-Years Warranty] This Power Circuit Probe Tester Kit Packing List: KM10 Automotive Circuit Probe Tester, User Manual, Cigarette Lighter Adapter, Battery Clip, Steel Probe Tip, 20ft Extension Cable, Carrying Case. Missing Parts Or Got A Used Item? Just Email Support@kzyeetech. Com With Your Order Number And Photos, We'll Resend A Replacement Within 24 Hours. Enjoy 3-Year Warranty, 30-Day Returns & Lifetime Tech Support. We've Got Your Back, Always.

[Instany Identify Polarity] Autel Car Circuit Tester Instantly Checks Component Continuity And Quick Identifies Positive, Negative And Open Circuits. When The Positive Terminal Is Connected, Red LED Lights Up With Beep Sounds. When The Negative Terminal Is Connected, Green LED Light Up With A Low Tone. If An Open Circuit, Neither Of LED Light Will Not Light. The Indicator Light Is A Considerate Working Guide To Facilitate The Smooth Operation Of Detection.

[Continuity Test, Signal Circuit Test] KZYEE Electrical System Probe Tester Can Test The State Of Sensors, Quickly And Accurately Judge The Connectivity Of Circuit Via Transmit Signal, Performing Continuity Test. Two Ways To Test Continuity: 1: In Resistance Mode, If The Resistance Is 0.0Ω And The LED Lights Up, It Means Continuity. 2: Power Up The Connection Using The Power Switch, If The Circuit Breaker Trips, That Means The Resistance Is Low And There Is Continuity.

[Compnent Activation & Test] This Automotive Power Circuit Tester Lets You Activate And Test On-Board And Off-Board Components With Ease. It Supports A Wide Range Of Vehicle Systems, Including Blower Motors, Power Window Motors, Windshield Wipers, Rear Window Defrosters, Lights, Radiator Fans, And Fuel Injectors. By Sending The Required Signal To Each Component, You Can Quickly Determine Whether It Is Functioning Properly. Designed For Both Professional Technicians And DIY Enthusiasts, The Tool Works Hand-Held, In-Vehicle, Or With Grounded Connections, Providing Fast, Accurate Diagnostics And Making Electrical Troubleshooting Simple And Reliable.

[20FT Extension Cable, Built-In Flashlight] Kzyee Automotive Electrical Tester Comes With Extra 20ft Extension Cable In Addition To Its Own 20ft Cable, Allowing You To Access Any Position Of The Vehicle And Test It. Ideal For Trailer Wiring, It Can Be Tested Along The Vehicle Without Having To Find A Suitable Ground Point. The Built-In Flashlight Is Convenient For Detection, Even In The Dark Or Dim Environment, It Can Provide The Best View For Who Need To Work In Night.

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#TOP 3

VKALTUL Circuit Tester BT250, Car Power Circuit Probe Kit with AC DC Voltage/Resistance/Diode Test

VKALTUL

BT250

black

VKALTUL Circuit Tester BT250, Car Power Circuit Probe Kit with AC DC Voltage/Resistance/Diode Test, Short Finder,Overload Protection,Colorful Display for 6-30V Automotive Electric Systems,1.5M

9.5

FTB Score

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Features

[Quick And Easy] With This Automotive Circuit Tester Tool, You Can Determine At A Glance Whether A Circuit Is Positive, Negative, Or Open Without Having To Reconnect Clips From One Battery Pole To Another; Test For Continuity With Its Built-In Auxiliary Ground Wire; Test For Poor Ground Contact Immediately Without Having To Perform A Voltage Drop Test; And Trace And Locate Short Circuits Without Wasting A Fuse.

[Multi-Functional] The Main Functions Of The Electrical Tester Include: Voltage And Polarity Testing, Continuity Testing, Signalling Circuit Testing, Activating Components In Hand, Activating Components In The Vehicle, Activating Grounded Components, Checking For Poor Ground Contact, And Tracing And Locating Short Circuits. The Power Circuit Probe Tester Kit Supports Diagnosis Of Electrical Systems In Other Vehicles Such As 6-30V Cars

[User-Friendly Design] The Car Electrical Tester Has A Built-In LED Light That Makes It Easy To Work Even In Dark Or Low-Light Conditions, And A Colour Display With High Resolution That Allows You To View Data Clearly And Comfortably. Powered By Car Battery Or Cigarette Lighter, No Extra Batteries Or Cables Required, 1.5 Metre Test Leads

[Overload Protection] The BT250 Auto Circuit Tester Is Protected By An Internal Circuit Breaker, Which Provides Additional Safety Protection For The User. If Overloaded, It Will Trip And Automatically Disconnect The Protection Circuit. Before Using The Auto Circuit Light Tester, The Tester's Quick Self-Test Function Ensures That The Tester Is In Good Condition. Fuse Tester Output Current Can Be Reversed To Form A Loop Power Supply.

[4 Adjustable Modes] Test Light With DC Voltage Test Mode, AC Voltage Test Mode, Resistance Test Modediode Test Mode,the Test Light Probe Kit Can Also Detect The Resistance Between The Probe Of The Circuit Under Test And The Auxiliary Ground; The Diode Test Can Quickly Detect The Operation Of The Diode Assembly And Determine Whether It Is On Or Off.

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#TOP 4

JIMCOM 6V/12V/24V Circuit Tester Light

JIMCOM

B0C4KFL8K3

6V/12V/24V

JIMCOM Circuit Tester, 6V/12V/24V Test Light Automotive Truck Car Electrical Circuit Continuity Tester Test Light Indicator with Pen Tool Electrical System Tester

9.4

FTB Score

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The JIMCOM Circuit Tester is an essential tool for checking automotive circuits ranging from 6V to 24V. Its lightweight design makes it easy for you to carry around, while the illuminated handle indicates when a circuit connection is complete. Crafted from durable materials, it features a carbon steel handle and a stainless steel probe that allows you to access hard-to-reach areas. Additionally, its solid copper clip and insulated cover ensure safety while you work, protecting against electric shock and providing a secure grip.

What We Like

Lightweight and portable design

Durable materials used

Safe with insulated cover

Quick circuit checks

#TOP 5

Circuit Tester Car Fuse Tester 3-70V Digital LED Automotive Test Light Digital Display Voltage Tester Pen

RLMVGBX

KDC-239

Compact

Circuit Tester Car Fuse Tester 3-70V Digital LED Automotive Test Light Digital Display Voltage Tester Pen Cover

Circuit Tester Car Fuse Tester 3-70V Digital LED Automotive Test Light Digital Display Voltage Tester Pen with Retractable Spring Wire And Crocodile Clip for Wiring Circuit Checking (No Battery)

9.2

FTB Score

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Features

[Easy To Carry] This Long Probe Pen Circuit Tester Features A Coiled Spring Wire That Is Lighter And Smaller Than Other Styluses, So It Doesn't Need To Take Up Much Space In Your Toolbox Or Any Other Storage Area.

[Wide Application] This Circuit Tester With Alligator Clips And Indicator Light Can Be Used To Detect Power Ground And Find Shorts And Breaks In Wires, Quickl.fuse Tester

[Material] Sharp Stainless Steel Probe For Piercing Wires, Also Suitable For Hard To Reach Narrow Areas. Insulation-Protected Rubber Tip Protects You From Electric Shocks. Heavy Duty Test Light Body Made Of High Quality ABS, Which Is Sturdy And Durable, Resistant To Electricity And Heat.

[Indicator Light And Digital Display] The Socket Tester Features An Indicator Light On The Handle That Illuminates When The Circuit Connection Is Established. Additionally, It Is Equipped With A Red Digital Display That Allows Users To Easily Read And Interpret Test Voltage Results. The Anti-Bending Design Of The Tail Wire Ensures Secure And Reliable Contact During Testing.

[Bidirectional Voltage Testing] You Can Attach The Alligator Clamp Either To Negative Or Positive Ground, There Is Also A Light Emitting Diode On The Circuit Board For Polarity Indication, Red Light Indicates Positive Polarity And Green Light Indicates Negative Polarity. 5-90V Low DC Volt Circuit Test Light, Designed For Checking Various Vehicles' Electrical Circuits, Such As Automotive Headlights, Taillights, Faulty Sockets, Fuse, Also For Testing Other 5-90V DC Wiring And Circuits.

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#TOP 6

Rapid Revive - Automotive Circuit Voltage Tester 3.5-36V DC

Rapid Revive

5060990470783

Blue

Rapid Revive - Automotive Circuit Voltage Tester 3.5-36V DC Cover

Rapid Revive – Automotive Circuit Voltage Tester 3.5-36V DC – Car Battery Short Circuit Finder with Digital Display, Electrical Fuse Tester, LED Light, Overload Protection & Long Test Lead

9.2

FTB Score

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Features

Fast Polarity Identification – Red Light Indicates Positive, Green Light Indicates Negative; Also Supports Continuity Testing And Jumper Lead Operation.

Multifunctional Tool – Supports Voltage Detection, Continuity & Diode Testing, Polarity Check, Ground Detection, Short Circuit Tracking, And Component Activation.

Wide Compatibility: Works With All 3.5V–36V DC Electrical Systems Including Cars, Trucks, SUVs, Motorcycles, Boats, And Construction Vehicles

No Messing Around: Extended Cable Length Covers The Entire Vehicle - Simply Connect Clips To The Car Battery And Begin Testing Circuits Quickly And Accurately.

Built-In Overload Protection: Auto Disconnects When Current Exceeds 7A With Buzzer Alert; Includes Self-Test Function For Safer, Reliable Operation.

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#TOP 7

ZKTOOL LED Power Circuit Probe

ZKTOOL

ZKEU650

blue

LED Type

ZKTOOL LED Power Circuit Probe, Automotive Electrical System Tester DC 6-24V, Car Circuit Tester, Short Circuit Tester, Voltage Tester, Polarity Identify, Test Light, Component Activation

9.2

FTB Score

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Features

Features: Compared With Traditional Power Circuit Probe Kits, This LED Power Circuit Probe Kit Has Safer Operation, Protects The Vehicle Computer Board From Potential Damage And Burning, And Adopts Sharp Probes To Easily Pierce The Wires And Enter Narrow Areas.

Function: Continuity Tester For Testing Components Inside And Outside The Vehicle Electrical System: This Electrical Tester Can Be Used To Test And Activate Components Inside And Outside The Vehicle Electrical System, Testing Voltage Polarity, Relays And Diodes, Fuses And Circuit Continuity, Checking Lights, Checking Motors, Track And Locate Short Circuits, Test For Poor Grounding, Test Cable And Plug Polarity, Measure 6V To 24V DC Voltage, Etc.

Remind: Do Not Use This Item Near Explosive Gas, Vapor Or Dust. When Pressing The Power Switch (Note: Or Shaking), The Battery Current Will Be Directly Conducted To The Pen Tip, Which May Cause Sparks Can Be Caused When Touching The Ground Or Certain Circuits. Do Not Use The Device Under 110/220V Indoor Current, Only For DC6~24V System. There Are Detailed Instructions In The Product Box, Please Refer To The Operation.

Friendly To Use: This Circuit Tester Light Is Equipped With A Bright LED Backlit Display, Ensuring Visible Test Voltage Readings In Low-Light Or Glare Environments.

Application: LED Light Prompt Helps You Quickly Identify Positive And Negative Polarity Of Electric Cables And Plugs. When The Probe Tip Contact To The Positive Electrode, The RED Light On. When The Probe Tip Contact To The Negative Electrode, The GREEN Light On.

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#TOP 8 Best Digital Circuit Tester

KAIWEETS Smart Circuit Tester with Backlight

KAIWEETS

VT501

Black

KAIWEETS Smart Circuit Tester with Backlight Cover

KAIWEETS Smart Circuit Tester, 0.8V-100V DC Voltage Tester with Backlight, Digital Test Light with Flashlight Measures Polarity Continuity, Automotive Fuse Tester for Car Battery

9.2

FTB Score

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The KAIWEETS Circuit Tester is an innovative tool that simplifies your electrical testing tasks. With its SMART mode, you can effortlessly measure AC/DC voltage, polarity, resistance, and continuity without any manual adjustments. The tester supports a wide voltage range from 0.8V to 100V, making it ideal for various automotive circuits. Its user-friendly design includes a long, durable wire and a large alligator clip for easy one-handed operation. Additionally, the clear green LED display ensures you can read measurements accurately in any lighting condition.

What We Like

Automatic measurement detection

Wide voltage testing range

User-friendly design

Bright LED display

Durable construction

#TOP 9

2Pcs Car Electric Circuit Tester Set

selliner

SLUK-101

black, red

2Pcs Car Electric Circuit Tester Set Cover

2Pcs Car Electric Circuit Tester,3-48V DC Battery Testers with Digital LCD Display, Auto Voltage Continuity Tester with Extended Spring Wire for Car,SUV,RV,Truck,Lawn Mower,Power Tool

9.1

FTB Score

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The Selliner Circuit Tester is an essential tool for anyone working with automotive electrical systems. It includes two testers, one black and one red, specifically designed for testing 3-48V DC voltage, allowing you to check various vehicle circuits like headlights and faulty sockets. The unique stainless steel probe and anti-bending tail wire provide durability and ease of use. Plus, the extended 78-inch spring wire gives you the flexibility to access hard-to-reach areas, making diagnostics simpler and more efficient.

What We Like

Durable stainless steel probe

Extended flexible spring wire

Easy-to-read LED display

Bidirectional voltage testing

Ideal for various vehicles

#TOP 10

CarBole Circuit Tester 6-48V,Power Circuit Probe

CarBole

Circuit Tester

CarBole Circuit Tester 6-48V,Power Circuit Probe,Auto Electrical System Tester,Equipped with a 13foot (4m) Long Test Lead,Suitable for Voltage Tests and Short-circuit Detection

9.0

FTB Score

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Features

Wide Compatibility：Suitable For All 6V-48V Electrical Systems, This Tester Works With Cars, Trucks, SUVs, Motorcycles, Construction Vehicles, And Boats. It Can Directly Connect To The Vehicle Battery, Making It An Essential Tool For Both Professional Mechanics And DIY Enthusiasts Dealing With Various Vehicle Types

Multifunctional Diagnostic Capability：This Circuit Tester Is An All-Round Solution For Automotive Electrical System Diagnosis. It Supports A Wide Range Of Tests, Including Voltage Detection, Polarity Identification, Continuity Testing, And Component Activation. Whether You're Troubleshooting A Short Circuit Or Testing A Diode, Its Comprehensive Functions Enable Quick And Accurate Problem - Solving, Significantly Reducing Diagnostic Time

User-Friendly Design：Featuring A 13foot Extended Detection Line And Intuitive Operation, The Tester Allows Easy Access To The Entire Vehicle's Electrical System. The Built-In LCD Display Clearly Shows Voltage Values, And The Front-Lighting Design Helps With Testing In Dark Environments. Additionally, The Overload Protection Ensures Safe Use

Safety And Durability：The Tester Comes With Overload Protection, Automatically Disconnecting When The Current Exceeds 20A And Sounding A Buzzer Alert. Made Of High - Quality Materials, It Is Durable And Reliable, Providing Long-Term Service For Automotive Electrical System Diagnostics

Precise Detection Features：Equipped With Advanced High-Sensitivity Probes, The Tester Offers Accurate Polarity Identification. The Red And Green LED Lights Clearly Indicate Positive And Negative Polarities. It Also Excels At Short-Circuit Tracking, Quickly Pinpointing Faulty Wires With The Help Of Its Sensitive Probes, Ensuring Efficient Problem - Solving

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Frequently Asked Questions (FAQs)

1. What instrument is used to test a diode?

The Diode Test Mode is the best way to test a diode as it relies on the characteristics of the Diode. In this method, the diode is put in forward bias and the voltage drop across the diode is measured, using a Multimeter. A normally working diode will allow current to flow in forward bias and must have voltage drop.

Editor's Notes

During our diode circuit tester research, we found 41 diode circuit tester products and shortlisted 10 quality products. We collected and analyzed 5,992 customer reviews through our big data system to write the diode circuit testers list. We found that most customers choose diode circuit testers with an average price of £17.31.

The diode circuit testers are available for purchase. We have researched hundreds of brands and picked the top brands of diode circuit testers, including OBDResource, KZYEE, VKALTUL, JIMCOM, RLMVGBX.

Written by

Jennifer Fraser

Jennifer Fraser is a licensed contractor specializing in sales, maintenance, and kitchen, bathroom, and home appliances, tools, and utilities. She owns a store in Leeds where you can get any home and tool appliance. Jenny has a degree in literature, but she combines her knowledge and experience with her degree to publish DIY articles on solving home appliances issues to keep up the family enterprise.