How to choose a transistor-meter ? - Page 1
Forum section: electronics / beginners

author: myf
author_rank: Regular Contributor
timestamp: March 06, 2019, 06:20:08 pm
content: Hi everybody !I want to test and sort transistors, Zener diodes and others components, i am looking for a solid case and an English display.I prefer devices powered by a rectangular 9V-6F22 battery, but I only find device with small lithium-ion battery.Theses devices t7 and tc1 are on aliexpress and ebay for about 15-20eur (= usd17-22).http://www.aliexpress.com/item/LCR-TC1-3-5-160-128-TFT-Color-Display-Graphic-Multi-function-Backlight-Transistor-Tester-for/32974681318.htmlhttp://www.aliexpress.com/item/2016-T7-New-Transistor-Tester-TFT-Diode-Triode-Capacitance-Meter-LCR-ESR-meter-NPN-PNP-MOSFET/32782708054.htmlI don't know which I'll choose. Which one has one a more electrical robustness ?User manual explains that more than 4.5Volt input may destroy the device.Can I test :BJT npn and pnp gain ? Even for Draligton transistors ?capacitance ? with its serial resistor ?Zener diode and led ? until 30Volt ?Triac and thyristor ?mosfet transistors ?Do you have any advice about this device? (or other ones)I post in this beginner forum because I don't want to change the device firmwareThank you a lot.F. from France.

author: schmitt trigger
author_rank: Super Contributor
timestamp: March 06, 2019, 06:54:16 pm
content: Scrolling down on the2017 T7 New Transistor Tester TFT Diode Triode Capacitance Meter LCR ESR meter NPN PNP MOSFET IR Multifunction tester multimeterwebpage, there is a table which describes the device performance and capabilities. What you can read from there, is what we can also read.It does not specifically list Darlington BJTs, but very likely it would.But if you want to be 100% sure, because the feature is particularly important to you, then you should contact the seller and directly ask the question.For the price, I would not expect them to be very robust. Things that usually fail in cheap devices, are flimsy connectors becoming intermittent, the onboard battery not holding the charge, stuck display pixels, etc.But this is an entry level product, which hopefully will last long enough for you to acquire something better later.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 06, 2019, 07:08:06 pm
content: Testing zener diodes will be limited with these cheap 1 µC solutions, as there is obviously no voltage higher than some 5 V. So only low voltage zeners would shown as such.I don't know about gain with darlingtons, but this is likely also difficult. Here the measurement may not be accurate. In addition some Darlingtons include resistors that alter the behavior at low currents that are usually used for such test. So a single gain number is not a good description.Triacs and tyristors can also be tricky as the test current is limited. So higher current devices may not be detected and AFAIK there is no measurement for the trigger current.MOSFETs usually are detected, except for a few with a rather high threshold (e.g. > 4 V)

author: kripton2035
author_rank: Super Contributor
timestamp: March 06, 2019, 07:20:35 pm
content: Quoteno I tested 27v zeners with one comparable tester and they were detected fine. there is a small transformer inside these testers (the one that have a KAA marked on the bottom of the zif socket) and they test zeners till 30V normally.

author: kripton2035
author_rank: Super Contributor
timestamp: March 06, 2019, 07:21:56 pm
content: Quoteyes agree. don't buy these kind of testers in the idea to test triacs and scr's you can only test low current low voltages ones and they aren't many.

author: Audioguru
author_rank: Super Contributor
timestamp: March 06, 2019, 07:50:28 pm
content: Why do you want to test and sort transistors? Don't you buy genuine ones? I have never saved a few cents (francs?) by buying then testing cheap factory rejects from "you know where".I design transistor circuits so that they work perfectly if a name-brand transistor has minimum, typical or maximum spec's. I also use a voltage regulator when one is needed.I notice that the meters you selected are probably VERY cheap no-name-brand from "you know where".

author: Kleinstein
author_rank: Super Contributor
timestamp: March 08, 2019, 07:08:11 pm
content: These testers still have there use. It can be handy on repair to check possibly broken and unknown parts. It's also handy when doing experiments on a bread board or so to see if the parts are still OK, or broken and even to verify the pin-out.Even the capacitor test is not that bad.The downside is that there is very little protection - so one has to be a little careful on use, especially with caps that may still hold higher voltage and not use this unit for in circuit tests.

author: runaway
author_rank: Contributor
timestamp: March 09, 2019, 08:29:50 am
content: Testers mentioned above don't recognize IGBTs. I got the the first one (by links list) for $6 only - the very same one but no case and probes (any need). So, as I just said it doesn't see IGBTs, it shows them as a diode. The second: capacitance of MOSFET' gate will be multiplied for misterious coefficient (many times!), which will be different each time. o_0 The rest it seems to be okay (pnps, npns, jfets, diacs, triacs, leds, zeners up to 4V5, capacitors' capacitance, ESR and losses percentage, inductors' inductance and ohmic resistance) - if your job is to sort out a bunches of transistors by parameters, the device is the very thing you need! Darlingtons? Well I steel have not the case, sorry!

author: Calambres
author_rank: Frequent Contributor
timestamp: March 10, 2019, 11:19:26 am
content: This thread comes just in time...

author: myf
author_rank: Regular Contributor
timestamp: March 10, 2019, 06:49:39 pm
content: Hi everybody,Thank you at every author for your description, your feeling, your advices, your tips.I better understand ability and limits of theses devices.On this forum getting more than one advice is precious.So I buy the recent tc1 on aliexpress.com for about 15eur.Have a nice day !F.

author: myf
author_rank: Regular Contributor
timestamp: May 12, 2019, 05:19:43 pm
content: Hello,I got this tc1 device. It works as expected.Results are fine for PNP and NPN Darlington transistors. Displayed gain for bc516 and bc517 transistors is about 30k or 40k.It's very funny to play with 2-colors leds with 2 pin or 3 pin. Zener diodes are described as 2 diodes mounted head-to-tail.Of course device doesn't detect lm317 and lm337 variable tension regulators, but lm7805 fixed tension regulator is described as 2 diodes.I also test the Zener abilities for this device :With tc1 and a ut61e I get forZener=5.6V - tc1=5.76V - ut61e=5.730V ut61e=3.527mAZener=13.0V - tc1=13.0V - ut61e=13.090V ut61e=2.775mAZener=27.0V - tc1=26.8V - ut61e=26.94V ut61e=1.375mAtc1 can't measure 30V-Zener.The ut61e has two peak-measures : peak-min and peak-max.With the 5.6V-Zener, peak currents are about +/- 9% from 3.25mA to 3.78mA, and peak tensions are around 1%.I test capacitors from 1nF to 4.7mF. I get the same measure for polarised capacitors in both ways, but measures for very large capacity varies : ut61e=5.78mF and tc1=6.09mF.Battery allows about 30 or 50 tests. Phone-charger and its standard cables are fine.Have a nice day !F. from France.