MK-168 Transistor Checker
Fig. 1 MK-168 Transistor Checker

Comparing ATmega328 Based Transistor Checkers

by Lewis Loflin

See the video Testing the Kuman Multifunction Transistor Checker.

The MK-168 and Kuman multifunction transistor checkers and the many related clones are inexpensive transistor checkers. Both check far more than just transistors, but a number of semiconductor and passive components as list below.

Both are available on Amazon as of 4-20-2018.

I own both models and discuss their use in the YouTube videos list below.

They are useful for general information on components and for transistors and dual diodes identity pin connections. Both are powered by a 9-volt battery and have auto power shutoff.

The MK-168 with its 3-pin plug-in ZIF board and three clip cables makes checking large components such as TO-3 easy. The Kuman checker has neither and is limited to small parts the fir the ZIF socket.

The color display in the Kuman was nice cosmetically to the plain LCD display of the MK168. It displayed a picture of the device including internal diodes and pinout of transistor and MOSFETs, etc. The MK-168 was text only.

Problems

I did encounter problems with both. The MK-168 had some bad internal solder joints I had to go into and fix.

While it did check low power sensitive gate SCRs it couldn't check most SCRs and no triacs I tried. This is understandable using a 9-volt battery.

The Kuman has some big problems. The ZIF socket is not soldered in and doesn't fit flush with the top of the case as shown below. The case is almost too small to the point a could barely get the 9-volt battery into the tester.

To get around the ZIF socket problem I built my own adaptor as shown in the video.

I found the same SCR and triac problem I had with the MK-168.

The Kuman also has a firmware glitch. If sitting a white pressing the test switch it comes right on. Most of the time I had to switch it off than immediately back on (test) then it worked.

The Kuman was unreliable in checking LEDs as where the MK-168 did a good job.

In my final analysis I preferring the MK-168 over the Kuman tester.

New April 2018:


Features MK-168:

LCD backlight display for easy readings.

Micro-controller uses 8MHz external crystal, the measurement accuracy is better.

One key operation with automatic power shutdown.

Can be powered by 9V battery (not included), also has external power interface for convenient use.

Automatic detection of NPN and PNP bipolar transistors, N-Channel and P-Channel MOSFETs, JFETs,

Diodes, double diodes, Thyristors and bidirectional thyristor, and LEDs. Note: my test show many higher power SCRs and triacs can't be tested.

Automatic identification components pin arrangement.

Measures current amplification factor and base-emitter threshold voltage of bipolar transistors.

It can detect bipolar transistors and MOS transistors protection diodes.

Measures the gate MOSFET threshold voltage and the gate capacitance.

Resistance measurement resolution is 0.1 ohms, 50M ohms can be measured.

It can measure capacitance of 25pF~100mF, resolution 1pF.

2uF above capacitors can simultaneously measure the equivalent series resistance ESR values.

Can display in correct order and the diode symbol display two diodes, and gives the diode forward voltage.

Notice: Before measuring capacitance, the capacitor must be discharged, otherwise very likely damage the meter.

Specifications:

Display: LCD Backlight
Input Voltage: 9V
Current: Approx. 20mA
Power Supply: 1 * 9V Battery (NOT Included)
Resistance Measurement: Max. 50Meg. Ohms
Resistance Resolution: 0.1O
Capacitance Measurement: 25pF~1000mF
Capacitance Resolution: 1pF
Inductance Measurement: 0.01mH-20H

Kuman Transistor Checker
Fig. 2 Kuman Transistor Checker

Kuman Transistor Checker ZIF socket problem.
Fig. 3 Kuman Transistor Checker ZIF socket problem.

The following is from the Amazon website.

WIDE APPLICATION: A must have for any electronic test bench. This multifunction tester can be used to test bipolar transistors, field-effect tube(FET), diodes, MOSFET(MOS), SCR,resistor, capacitor, Inductor, thyristors which is available for various electric transistor testing.

SIMPLE TO OPERATION: Transistor Tester Come with User guide. Only 2 Short detection time. Two-button operation, automatic 40-second countdown shutdown to avoid unnecessary waste. Powered by DC 9V battery(not included).

AUTOMATIC IDENTIFICATION: Automatically detect NPN and PNP transistors, N-channel and P-channel MOSFET, JFET FET, dual diode, silicon controlled rectifier, capacitor´╝łeven 25pF mica capacitor´╝ë, and pin definition. J-FET, PMOS, NMOS, Silicon-diodes of various sizes and LEDs.

LARGE & CLEAR LCD DIGITAL DISPLAY: 1.8" 128*160 TFT high-resolution display with Blue back light , different parameter is shown with different color, it is more convenient for you to check the parameter.