DROK Transistor Tester LCR Meter, Mosfet Transistor Capacitor Tester, Mega328 NPN PNP Transistor Diode Resistor Inductor Capacitance MOS SCR ESR Meter Automatic Checker Detector

First one I bought failed after reading about 20 components. The replacement has been working good so far.

Works fast. DOES NOT test unijunction transistors, silicon unilateral switches, or silicon controlled switches (old analog exotic devices). DOES test JFETs, SCRs, MOSFETs, BJT's and diodes.

Great - works on every component I could find!

This device is invaluable in its flexibility and simplicity. A couple of things to keep in mind:1. This is 9V battery version of this. It will eat batteries quickly, on the order of needing a new battery every 200-250 tests. I switched to the rechargeable USB version.2. There are several versions of this device on the market. They range in price from this one being about the most expensive to others that are less than half the price of this one. Internally they are all the same. Prefer the one that provides the best price/value in terms of attachments and test leads. You will get the same results regardless of how much you pay for one of these simple devices. The one I switched to is currently $19.95USD. It has leads, and it construction is superior to this one.3. As far as simplicity, It’s not important which holes the component under test goes in as long as they are close together and into the left side of the plug. I find I get better results by following this simple guideline. Positioning of the leads in any specific order is not necessary. And that is the beauty of this device. It figures it out for you!

I spend a good amount of time troubleshooting electronic faults at work, replacing faulty components. In many cases, I am working with circuit boards that I don't have the ability to power on the circuit using a DC power supply or batteries, for regular troubleshooting by measuring voltages with a DMM and a oscilloscope.This device is handy, it's always with me.For example, some LEDs can be tested using a DMM such as Fluke, set to the diode test measurement, depending on the power requirements for a particular LED and its color and illumination characteristics. On some LEDs one can see the diode light up briefly using a Fluke (or other DMM). Some LED's however will not illuminate using just a diode tester on a DMM. When testing LEDs, I reach for this device before a DMM, it reliably illuminates and LED with briefly or a rapid series of pulses, including Cree LEDs.As another reviewer has mentioned, not all circuit-testing is done on live circuits simply because the ability to energize the circuit may not be feasible or possible. This device has saved me a lot of time where a circuit arrangement that I test results in a complete oddball of a test result, such as reporting a double diode instead of a bijunction transistor, or other circuit boards do not result in the same repeatable test result for faulty boards, while the board is not energized.I could not do my work without a multimeter available as my most important tool, I simply wouldn't bother. At the same time, this device reports results that are arrived at by intuition and practice using just a DMM.One other valuable function of this device is that I can take a number of transistors and get a consistent reading for range of performance so that I can match a number of transistors in cases there they must perform almost equally well. Using this device is far simpler than creating a test fixture to test transistors so they can be matched. I do this even with resistors too, 1% tolerance sounds nice but is not always the case--I use the ohmmeter function on my DMM for that, it's simple. For testing transistors or diodes, this device makes segregating similar performers together, much simpler.I haven't even needed to change the 9V battery in almost two-years of use.

The Drok tester is similar to many units, but is better built than most. The product includes a zero insertion force socket which may be plugged into the header socket holes protruding from the front of the unit. The fit of the ZIF could be firmer, and it probably would have been just as well to mount the ZIF to the circuit board and not bother with headers.The operation is pretty straight forward and the unit had no trouble identifying various types of thyristors, junction transistors, MOSFETs and diodes I tried. The only device which tripped up detection was a 50 Amp Schotty diode, which showed as “no component.” To be fair, that diode also eluded an expensive tester. I know the diode is good because it behaves properly under load.I believe this tester is a handy addition to have on the work bench as long as you keep your expectations realistic about what it can do.