Cool Tools:  Pen Type Digital Multimeter - Review

Table of contents

RoadTest: Cool Tools:  Pen Type Digital Multimeter

Author: dixonselvan

Creation date:

Evaluation Type: Test Equipment

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: Shanghai Mastech MS8211D ($19.95), UNI-T UT118A ($22) - There is no visual difference in appearance between this multimeter and the road test unit, the road test unit Tenma pen style meter 72-9390 is priced at $36.59. The prices mentioned here are taken from Amazon.com as on July 29, 2018.

What were the biggest problems encountered?: 1) The power cum mode (Voltage measuring mode/ Resistance, Diode, Capacitance and Continuity testing mode) switch is hard to slide. When we slide it, it moves to the other extreme and does not stop in the middle at times. 2) The Display has edges which are a bit curved at the edges which limit the angle of vision and makes it hard to read unless you have the backlight turned ON.

Detailed Review:

Last Modified Date & Purpose - August 09, 2018 & Road Test Review Creation

Introduction

 

    Like the stethoscope for a doctor, multimeters are for Electrical/ Electronics engineers. Multimeters come in various sizes and models, manufactured by different manufacturers. The common multimeters are like the one in the picture #1 [Tenma 72-2595] below. Have you ever struggled while using one of them? Let me tell my reason for the struggle. These kinds of multimeters have a display with a multimeter unit and the probes separate. Whenever you need to have a look at the value of current/ voltage across components in your PCB, you have to locate them using the probes and then look at the display in the multimeter unit. During this process, sometimes you tend to move the probes away unknowingly from the expected position and then you have to relocate the probes again. Some have alligator clips to hold the probes in place. But still, we have some components where we can not use clips to hold and need the probes to be held in position. Also, what if the location where your PCB is mounted does not have proper lighting? Either you need to light the area using a torchlight or you have to take the PCB out.

             

  #1 - Common Multimeter              #2 - Pen Style Multimeter

 

    But what if your multimeter, probe, and a torchlight are combined together? See it in the picture #2 [Tenma 72-9390] above, the handheld Tenma pen style digital multimeter priced around $37. Also, Tenma is not the only company which manufactures this type of multimeters. See some of the similar products above, under the title - ‘Comparable Products/ Other parts you considered’.

 

    To know more about multimeters, I suggest to check out the Wikipedia article in this link. This will be my road test review of the Tenma 72-9390 pen style digital multimeter. Click here if would like to know About me.

 

Table of Contents

Plan

 

    The road testing process of this pen style multimeter is split into the below stages along with duration to complete, as per the plan proposed in the road test review application. As usual for every other road test I do, the first would be an unboxing and the out of the box experience video. Next is to test the functionalities mentioned in the product's package case followed by a comparison with the multimeters that I have.

 

    • Unboxing and First Experience with video - 1 week
    • Test all of the below-mentioned functionalities - 4 weeks
      • AC/DC voltage
      • EF Function
      • Resistance
      • Diode
      • Continuity
      • Capacitance
    • Compare it with Tenma's 72-2595 Digital Multimeter and a cheap DT830D Multimeter - 3 weeks

 

Unboxing and First Impression

 

    The package arrived in great form. Thanks to , Element14 community and UPS for the delivering the product safely. Inside the package case, we have

    • a Multimeter unit,
    • a Ground/ Negative probe,
    • CR-2032 3V Lithium battery and
    • an Operating Manual in English.

 

    The multimeter unit has a black body and an orange top. This is a positive probe continued with a display. It has functional buttons and a switch at the front. We have options to insert battery at the back. The ground/ negative probe is pretty good in quality and comes with a cap to protect the lead when not in use. The operating manual has all the pieces of information to get started out of the box along with safety precautions and warnings. Check out the video below for the Unboxing of the Tenma pen style digital multimeter.

 

 

Specifications

This section has contents that have been taken from the Operating Manual.

    The Tenma 72-9390 uses a large-scale Integrated circuit with professional multimeter IC as its core and has full range overload protection. This a 3000 counts pen type digits multimeter which means the maximum value that can be displayed is 2999. The meter is compliant with the EN61010 standard: in pollution degree 2, overvoltage category (CATIII 300V) and double insulation. CAT.III: Distribution level, fixed installation, with smaller transient overvoltages than CAT.IV.

 

    The below image explains the various parts of the multimeter. It has a positive lead at the front top inside an orange cap. Pull down and twist the orange cap counter-clockwise to expose the input terminal. This is followed by the functional buttons which are as follows:

 

    • Display Backlight button - To turn on and off the display backlight and test lead LED (It will automatically turn off after a minute).
    • Select button - To switch between resistance, AC/DC voltage, continuity, and diode measurement mode.
    • Max/ Min button - To store maximum and minimum input values.
    • Hold button - To hold the value obtained.

 

    Then, we have a slide switch to switch between the various mode (Voltage / Resistance, Capacitance, Diode, and Continuity test mode) and it is can be used to turn off the meter manually. By pressing and holding the select button, the meter enters into sleep mode. It has a non-rotatable fixed LCD display with backlight.

 

Basic Functions

This section has contents that have been taken from the Operating Manual.

FunctionRangeBest Accuracy
DC Voltage3V/ 30V/ 300V±(1%+3)
AC Voltage3V/ 30V/ 300V±(1%+4)
Resistance300Ω/ 3KΩ/ 30KΩ/ 300KΩ/ 3MΩ/ 30MΩ±(1%+3)
Capacitance3nF/ 30nF/ 300nF/ 3µF/ 30µF/ 300µF±(3%+5)

 

    AC/ DC voltage

To avoid damage to the meter, never input greater than 300 voltage

              The maximum voltage which could be measured without damaging the meter is 300V. To measure AC/ DC voltage, you have to do the following steps:

      • Slide the switch from 'OFF' to 'V' (with ~ AC & - DC symbol on top of it) in order to measure the voltage.
      • Place the positive lead on the positive end of the voltage source and vice versa for ground/negative.
      • By default, the meter is in 'Auto Scan' mode. You can toggle between Auto Range AC and DC by pressing the select button.
      • The voltage of the source/ battery will be displayed on the LCD Display in the meter.

 

To avoid damages to the meter or to the devices under test, disconnect circuit power and discharge all the high-voltage capacitors before performing the below measurements/ tests

    Resistance

               To measure the resistance, you have to do the following steps:

      • Slide the switch from 'OFF' to the other extreme (Resistance, Diode, Capacitance, and Continuity test mode).
      • Connect the test leads with the object being measured.

 

    Capacitance

               To measure the capacitance, you have to do the following steps:

      • Slide the switch from 'OFF' to the other extreme (Resistance, Diode, Capacitance, and Continuity test mode).
      • Connect the test leads with the object being measured.

 

Special functions

 

FunctionRange
Sleep Mode
Auto Ranging
Input Impedance for DC Voltage Measurement≥ 10MΩ
Diode
Full Icon Display
Continuity Buzzer
Sleep Mode
Max/ Min Mode
Data Hold
Display Backlight
Low Battery Display
Max Display2999

 

    Sleep Mode

              To preserve battery life, the meter automatically goes into a 'sleep mode' if you do not press any button for around 10 minutes. The meter can be activated by pressing any button, then it returns to the display for the function selected previously.

To avoid damages to the meter or to the devices under test, disconnect circuit power and discharge all the high-voltage capacitors before performing the below measurements/ tests

    EF Function

              To measure NCV, you have to  do the following steps:

      • Slide the switch from 'OFF' to 'V' (with ~ AC & - DC symbol on top of it).
      • Press the select button once to go to the Auto AC voltage measurement mode.
      • Place the meter near to the source whose NCV is to be measured.

 

    Diode

               To perform the Diode test, you have to do the following steps:

      • Slide the switch from 'OFF' to the other extreme (Resistance, Diode, Capacitance, and Continuity test mode).
      • Connect the test leads with the diode being tested.

 

    Continuity Test

               To perform the Continuity test, you have to do the following steps:

      • Slide the switch from 'OFF' to the other extreme (Resistance, Diode, Capacitance, and Continuity test mode).
      • Connect the test leads with the ends of the circuit whose continuity needs to be tested.

 

Comparison

 

     Below is the comparison chart of functionalities, specifications, and quality of Tenma 72-9390 (Pen Style Meter), Tenma 72-2595 and a cheap DT830D multimeter.

 

 

Tenma 72-9390

TENMA 72-2595

DT830D

Voltage Measurement (DC)

Maximum/ MINIMUM  value:

Yes (Auto-Ranging)

300V/ 3V

Yes

600V/ 200mV

Yes

1000V/ 200mV

 

 

 

 

Voltage Measurement (AC)

Maximum/ MINIMUM  value:

Yes (Auto-Ranging)

300V/ 3V

Yes

600V/ 2V

Yes

1000V/ 200V

 

 

 

 

resistance Measurement

Maximum/ MINIMUM  value:

Yes (Auto-Ranging)

30MΩ/ 300Ω

Yes

20MΩ/ 200Ω

Yes

2MΩ/ 200Ω

 

 

 

 

Current Measurement (dc)

Maximum/ MINIMUM  value:

NA

-

Yes

10A/ 2mA

Yes

10A/ 2000µA

 

 

 

 

Current Measurement (Ac)

Maximum/ MINIMUM  value:

NA

-

Yes

10A/ 20mA

NA

-

 

 

 

 

capacitance measurement

Maximum/ MINIMUM value:

Yes (Auto-Ranging)

3mF/ 3nF

Yes

200µF/ NF

NA

-

 

 

 

 

Special functions

Sleep mode,

Auto Ranging,

Low Battery display,

Diode,

Continuity Buzzer,

EF Function,

Max/ Min mode,

Data Hold,

Display Backlight,

Test lead LED

Sleep mode,

Temperature measurement,

Low Battery display,

Diode,

Continuity Buzzer,

Data Hold

Sleep mode,

Low Battery display,

Diode,

Continuity Buzzer,

 

 

 

 

Operating manual

Yes

Yes

No

 

 

 

 

Probe Quality

 

 

 

 

Build Quality

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     Below is the video showing the comparisons and functional tests performed using Tenma pen style multimeter and two other meters.

 

 

Conclusion/ Summary

 

     I am glad that I received this wonderful multimeter. This is small, portable and with all the required functionalities with desired specifications. Below are some of the pros and cons that I have noticed during the two months of this road test.

 

     Pros

    1. Sleep Mode.
    2. Easy to see the display while placing probes in components.
    3. Portable - You can carry it around as it fits in your pocket.

 

     Cons

    1. Length of the probe is short.
    2. The display would be convenient only for right-handed as it is fixed and can not be rotated.

 

     With this ends my review of the Tenma 72-9390 Pen-Style Meter.

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