2017-06-23 Transistor Tester Arrived

I received the transistor tester that I ordered a week or so ago.  I ordered this one preassembled (the price was only a few dollars more) and with the plastic case, which I have to assemble.  I ordered it from a seller on eBay for $20.

This is different than the component tester I bought last year.  This one has a green ZIF socket with the lever, a digital volume control in the lower right corner, and a color OLED display.  It also has two terminals above the display, and two sets of two terminals at the lower right corner.  The green ZIF socket has a mark above it on the circuit board showing the pin arrangement.  In both rows, the fourth pin is pin 2, the three to its left are pin 1 and the three to the right are pin 2.

I got some parts and started testing a few.  The first was a 625 ohm, 0.05% wirewound resistor.  This is super accurate, to within a third of an ohm.  The tester was also accurate, to within the same 1/3 ohm.  So that’s a very good sign!  But then the screen kept saying that it was not calibrated, and to short the three pins together and calibrate it.  It gave a website to get more information.

The website looked like it wasn’t correct so I went online and searched for transistor tester, and came up with several hits, so I clicked on a YouTube video of how to use it.  The guy showed how to short the three pins and get into the menu and start self test.  After I did that it no longer said it wasn’t calibrated.

The inductance test cannot resolve inductance less than .01 millihenry, which is the same as 10 microhenrys.  The resistance and capacitance tests seem to do better.

The tester said there was a 0.1 uF calibration capacitor with the tester, but I found no capacitor in the package.  But in any case, the tester said that the 0.1 uF capacitor that I had was 102.4 nF.  That’s about 2.4% high, which is well within tolerance.  The tester also gives a value for ESR, equivalent series resistance.  I don’t know how accurate it is, because there is no table or documents with the tester.  Some ESR testers have a chart attached to show maximum values for various types of capacitors.  But not this one.  ESR is given in ohms, so I could put a resistor in series with the capacitor to see if the ESR goes up.  I don’t know if this is the way it is done normally.

 Along with ESR it gives Vloss, a value in percent.  I assume this is calculated from the ESR.  I tested a 10 uF electrolytic capacitor and it said 10.70 uF  ESR=2.2 ohms  Vloss=4.2%   I tested a 104K 250V plastic capacitor, and it said 102.1 uF  ESR=1.6%.  The Vloss was blank most of the time, but occasionally it would pop up with a value of  .1%.  Then I tested a 100 uF 50 V electrolytic capacitor.  The tester displayed 102.3 uF  ESR=.28 ohms  Vloss=.7% .

I tested several very old molded mica capacitors from old radios.  One was large enough to give a reading of loss.  Another low value (I think it was 10 pF) mica was too low to be ‘seen’ by the tester, and it gave a ‘No, unknown or damaged part’ reading.  Another mica gave a reading of 142 pF and was marked 150 pF.  So I thought somewhere between those values, probably 100 pF, is the point where the tester stops sensing the capacitor.  Then I  a 100 pF capacitor and it gave me a reading of 95 pF.  Another just like it gave a reading of 100 pF.  I put a 56 pF mica capacitor on the tester and it gave a reading of 54 pF.  So maybe the no sense point is lower.

I tested a big dual diode removed from the heatsink of a PC SMPS.  I think these D83-004 diodes are 35 amp.  It tested as a diode with a V drop of only 170 mV, indicating that it’s a Schottky rectifier.  I tested another single diode in a TO-220 package, and it said there was 196 mV drop indicating it was a Schottky rectifier.

I connected the base and emitter leads of a TIP127 power Darlington transistor to the tester.  The Vf measured 1.26 volts (it said Uf, in some countries they use U instead of V).  This high value is because a Darlington has two base to emitter junctions connected in series.  This is also why the Darlington transistor’s collector cannot go below about 1 volt when it’s saturated.

In the last few days I’ve experimented with quite a few parts, testing them to see what this tester thinks they are.  The tester does okay with MOSFETs, power transistors, and even some dual Schottky power rectifiers.  It gives the reverse leakage current in uA or nA.  Also the capacitance in the reverse biased junction, but it’s only accurate for 5 volts.

It can’t see that the LEDs are putting out light, but it says they’re a diode, with a high Vf, like 2 to 3 volts.  I can see the LEDs flicker as it tests them.

The tester can’t tell if a diode is a zener because most Zener diodes have a voltage above 5 volts the tester uses, so they’re like a regular diode to the tester.

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