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Cool Tools:  Pen Type Digital Multimeter - Review

Scoring

Product Performed to Expectations: 9
Specifications were sufficient to design with: 10
Demo Software was of good quality: 10
Product was easy to use: 9
Support materials were available: 10
The price to performance ratio was good: 8
TotalScore: 56 / 60
  • RoadTest: Cool Tools: Pen Type Digital Multimeter
  • Buy Now
  • Evaluation Type: Test Equipment
  • Was everything in the box required?: Yes
  • Comparable Products/Other parts you considered: 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 rscasny, 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.

    Tenma 72-9390 Pen Style Multimeter Description

     

    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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