I recently was browsing electronic kits on various websites and noticed that there seemed to be a few component testers that can be bought, some are assembled and others need assembled. I purchased some and will show some of the features and results from testing a few components.
The first one is the following tester
It is described as a Multifunctional transistor tester for the automatic recognition of NPN and PNP transistors, N-channel and P-channel MOSFETs, diodes, thyristors, resistors, capacitors or other means. Easy and convenient to use.
Here are the features
The display is 12864 LCD backlit in white.
Powered by 3.7V lithium battery (not included) or 5V external power source with Micro USB port (Micro USB cable may not be included).
Recognizes NPN and PNP transistors, N-channel and P-channel MOSFET, JFET, diodes, inductors, resistors, capacitors, thyristors or other devices automatically.
Automatically test the pins of a component and show on the display.
Measurement of the gate threshold voltage and the gate capacitance of the MOSFET.
Measure. Bipolar transistor current gain and the base-emitter threshold voltage
Short Detection Time: 2 seconds. It takes more time for large capacitor detection.
Usage : This was taken from the manual
Using of the Transistor-Tester is simple. Anyway some hints are required. In most cases are wires with alligator clips connected to the test ports with plugs. Also sockets for transistors can be connected. In either case you can connect parts with three pins to the three test ports in any order. If your part has only two pins, you can connect this pins to any two of the tree test ports. Normally the polarity of part is irrelevant, you can also connect pins of electrolytical capacitors in any order.
The measurement of capacity is normally done in a way, that the minus pole is at the test port with the lower number. But, because the measurment voltage is only between 0.3 V and at most 1.3 V, the polarity doesn t matter.
When the part is connected, you should not touch it during the measurement. You should put it down to a nonconducting pad if it is not placed in a socket. You should also not touch to the isolation of wires connected with the test ports. Otherwise the measurement results can be affected. Then you should press the start button. After displaying a start message, the measurement result should appear after two seconds. If capacitors are measured, the time to result can be longer corresponding to the capacity.
Lets look at some results
Example 1 : a 5k1 resistor, tried several tests and the range seemed to be from 5111 to 5119 ohms
Example 2 : A 100nF capacitor, two images here. I noticed that the capacitor value fluctuated a fair bit, you can see this in the two screenshots below.
Example 3 : A transistor labelled as a C945 (Its a Chinese made one). After a google search I found it was NPN transistor made by JIANG SU CHANGJIANG ELECTRONICS TECHNOLOGY CO. Here is the result, you can see it recognizes that its an NPN type and importantly recognizes the pinout
The product is available from around the 15$ price, which seems quite reasonable
015 New version ESR Meter 12864 LCD Transistor Tester Diode Triode Capacitance /MOS/PNP/NPN M328 Multifunction Meter
Here is the manual for the tester