Wednesday, October 4, 2017

LCR-T4 Mega328 Component Tester

LCR-T4 Component Tester

I recently picked up an LCR-T4 Component Tester from E-Bay. I've had my eye on these for a while and for AUD12 (including the acrylic case), I thought it was worth giving one a try. There are LOTS of different versions out there.

So what does it do?

Well it measures components, including resistors (and potentiometers), inductors, capacitors, diodes, dual diodes , transistors (including MOS), SCR's, regulators, LED's, and even ESR.

Photo Credit: EEVBlog

The claimed accuracy is:

Resistance: 0.1 ohm resolution, maximum 50M ohm
Capacitor: 25pf -100,000 uf
Inductors: 0.01mh-20H

These are probably a touch optimistic but for picking out components, the accuracy is adequate.

Photo Credit: EEVBlog

This unit apparently comes with the 2013 M328 version of the software and includes a 128*64 backlit LCD display, which uses about 2mA in stand by. As you can see in the image above, the unit will automatically identify and tell you which pin is the BCE for a transistor, not to mention the gain and forward voltage - nice! One of the features is automated detection of pin assignment, which means the device can be connected to the tester in any order. You can only use pins 1,2,3 of the DIL socket.

The open source firmware and hardware design is based on the work of a couple of German dudes. If you were brave you could flash the firmware to the latest version.

Case Construction

Building the case is fairly simple. What takes the longest is peeling the paper from the laser cut acrylic sheets! Proceed as follows:

  1. Peel the paper from the acrylic (both sides).
  2. Mount the PCB on the base plate using the four smaller bolts and the spacers (see photos below). You may want to pass the battery cable under the PCB, but it isn't compulsory.
  3. Insert the side panels into the base, starting with the top one as it has the tightest fit against the screen ribbon cable.
  4. Snap the top plate in place, it will only fit one way. This should hold things in place while inserting the 4 long bolts and nuts which hold everything together. Done!

What Manual?

The first trick is to make sure that you use a fresh 9V battery, if you don't then the display will be unreadable.

Operation is pretty straight forward. Just plug the component that you want to test into pins 1, 2 or 3 on either side of the DIL socket, then press the blue test button. The unit turns itself off after displaying the results for 10 seconds. If you have surface mount components, you can use the pads on the PCB labelled 1, 2 and 3 instead of the DIL socket.

The unit will automatically detect NPN & PNP transistors, N- and P-channel MOSFETs, JFETs, diodes, small thyristors, and TRIACs. It will measure hFE and base-emitter-voltage for bipolar junction transistors (e.g. Darlingtons).

Up to two resistors can be measured with a resolution down to 0.1 ohm. The measurement range is up to 50 Mohm (Megaohm). Resistors below 10 ohms will be measured with the ESR and a resolution of 0.01 ohm. Note that resolution is not equivalent to accuracy.

Capacitors in the range 35pF (picofarad) to 100mF (millifarad) can be measured with a resolution down to 1 pF. Inductances of 0.01 mH to 20 H can be detected and measured.

The short video below shows an LED being tested.


  1. "Operation is pretty straight forward. Just plug the component that you want to test into pins 1, 2 or 3 on either side of the DIL socket, then press the blue test button."

    Does it matter which of those 6 pins you mention that a diode, LED or transistor gets plugged into?

    1. The socket has 14 holes or connection points. The pins opposite from each other are connected together. The first three holes on the right are "1","2","3" and all of the rest going to the right are all "1".