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Review of the DY294 Digital Transistor Tester-Part 1

By on June 2, 2010


Last week i was busy with the repair course and holiday and finally today i could review the meter. The DY294 Digital Transistor Tester is using 4 pcs of AA batteries and and this tester can be used to test on many type of components. Select to the range as shown in the photo below and you will know the total voltage of the internal batteries:


Below are the result of certain components that i have tested and i will proceed to provide more information on other components in part 2.

Voltage Regulator IC:

Just insert the IC to the respective point (point 1, 2 and 3) and press the TEST button and see the result

duoyi digital transistor tester dy294

 duoyi digital transistor tester dy294

Insulation Test on Non Polar Cap:

There is only one range for you to select to test the non polar cap- 1000v. The 200 volt produce no result when test on non polar cap. Set to 1000v to test on non polar cap that have working voltage of 1kv and above. For a good cap, it will show approximately 1500v and if the non polar cap insulation have problem, it will show a very low voltage from 60 to about 300 volt. This test have similar function like an insulation tester.

 duoyi digital transistor tester dy294

 duoyi digital transistor tester dy294

If you need to test on non polar cap that have working voltages that is less than 1000v then you may need to add a resistor in parallel so that the insulation of the non polar would not fail when you pump in the 1000volt to the cap. As for the resistor value you have to find it on your own because the manual does not comes with it. In the photo below, i found that the resistor of 560kOhm is suitable to test on a non polar cap that have 250 volt working voltage. If you use a lower ohm value the non polar cap insulation may breakdown. From the same photo you could see that the max voltage only hit 231 volt. If this non polar cap insulation have problem, the value could be less than 100volt.

digital transistor tester dy294

Testing on Electrolytic Capacitor:

For your information, this meter is not design to test on the ESR or the capacitance value of e-caps. It test just the same way for a non polar cap.  Just insert the e-cap into the respective section and select 200 VDC as shown in the photo and press the Test button. The LCD display will show the capacitor is charging and it will charge up to 200vdc-make sure that you are testing a cap that have working voltage higher than 200 volt.  The disadvantage of this test is you have to wait for the cap to charge up.

transistor tester dy294

duoyi digital transistor tester

The advantage of this meter over insulation tester is that it can be used to test on e-caps that have lower working voltage like 16 volt, 25 volt, 50 volts and etc. Just make sure that when you want to test a lower voltage of capacitor, the charging voltage should not exceed the working voltage. That means if you want to test a 16 volt cap, make sure the charging voltage would not exceed 16 volt. If there is a problem with the cap, there would be no charging or the charging would just stay at one value for example it stays at 8 volt and stop.

I found that this tester consume lots of current especially testing on the capacitor. If possible get a 6 vdc (2 amp) power adapter to power up this meter. In the long run, you could save the cost of buying batteries. Another thing is that if the batteries voltage is lower than 5.7 volt, i found that the test result would not be accurate especially testing on the non polar caps. Stay tune for more testing result in Part 2.



  1. beh

    June 2, 2010 at 2:09 pm


    thank you so much for all of your effort to test this multitester
    i am waiting for the next part of your test report here

    thanks again

  2. John Preher

    June 2, 2010 at 8:39 pm

    Looking really useful, I think I will definately order one of these. I like that it can be used as an insulation tester and for testing varistors.

  3. admin

    June 2, 2010 at 9:01 pm

    Hi John,

    Yes i recommend it too.


  4. beh

    June 3, 2010 at 1:11 am


    does DY test the VARISTORES as well as other components?

  5. tamakloe

    June 3, 2010 at 7:23 am

    Please where can one get this to buy and how much is it?

  6. admin

    June 3, 2010 at 9:12 am

    Hi Tamakloe,

    Here is the link:


  7. admin

    June 3, 2010 at 9:12 am

    Hi Beh,

    It does test the Varistor.


  8. Sam C

    June 3, 2010 at 4:15 pm


    The eBay seller in Guangzhou, China now wants $30 plus $15 shipping. Used to be free shipping. Here is the new eBay listing.
    The listing Jestine provided is sold out.

  9. daniel segura

    July 18, 2010 at 7:20 pm

    hello where i can buy this machine or dispositive and which your price ( my inglish is not good)

  10. admin

    July 18, 2010 at 8:50 pm

    HI Daniel,

    You can buy from this link:


  11. Arnold Codilla

    August 10, 2010 at 12:42 am

    how much the DY294 INSULATION TESTER?

  12. admin

    August 10, 2010 at 6:32 am

    Hi Arnold,
    If you visit the seller website in ebay, they are selling about USD55.00


  13. Charles H Rowe

    September 28, 2010 at 8:46 pm

    Purchased one of the dy294 tester the manual is in Chinese so that does not do you a lot of good.Tried some of the downloads for the English manual but they are not complete manuals.Just thought i would let the people know before ordering one.If selling in us should include English


  14. admin

    September 28, 2010 at 10:03 pm

    HI Charles,

    Thanks for the comment. But my side here I got Chinese and English manuals. The English manual is a bit blur but still can be read.


  15. J V L Siva Prasad

    March 10, 2011 at 3:56 am

    Please guide me that the Aqupment's (TOOL"S) like degital meaters YOU shown in the pictures And ALL other tools and for it's purposes & how to use.

    AND how mouch of it's prices & where I get that.

  16. admin

    March 11, 2011 at 4:17 am

    HI Siva,

    How this equipment can used already mentioned in this blog. For other equipment i suggest that you get this ebook at because it does show how to use analog/digital meter, digital capacitance meter, blue esr and ring tester to test on electronic components.


  17. Mircea

    April 24, 2011 at 7:01 am

    Very good this tester!I have a tester JL294-3 and I are very pleased with him.

  18. admin

    April 25, 2011 at 5:09 am

    Hi Mircia,

    Good to hear about the tester.


  19. Wimpie

    September 23, 2012 at 2:42 pm

    Hi Jestine
    When testing 400V cap with this tester can i put it on 1000V cause i saw your tester were on 200V just want to make sure and i have a 6V 500mA external power supply measuring over 7V with digital tester will this power supply be ok?
    Thanks Wimpie

    • Jestine Yong

      September 24, 2012 at 9:53 pm

      Hi Wimpie,

      If you use 1000v to test on the 400v cap I'm afraid it will explode because the 400v means it is the highest rated voltage. The external voltage is 7 volt when there is no load but with load it will go down thus you can use it on your meter.



    November 6, 2013 at 4:09 pm

    does it support to test ZENER diode or DIAC ?
    i want to invest this too !

    • Jestine Yong

      November 7, 2013 at 9:17 pm

      HI Steven,
      Good question. I have not tested these components yet. If I have the time I will test it out.


  21. mehrdad

    May 6, 2015 at 11:35 pm

    how can i buy this instrument?
    transistor tester model jl294-3

    • Jestine Yong

      May 7, 2015 at 11:13 am

      Hi Mehrdad,

      Try visit ebay and type in this keywords - DY294 Digital Transistor. You can check the latest price there.


      • Willie

        June 11, 2018 at 4:03 am

        Did you ever do part 2?

        • Jestine Yong

          June 13, 2018 at 9:15 am

          Hi Willie,

          Here is the part 2 and 3:



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