Transistor Tester?

[Kinski]

I know a few people around here use the Peak DCA55. But I don't feel like dropping that kind of cash.

Anyone know if these are at all decent?

http://www.ebay.com/itm/Transistor-Tester-Capacitor-ESR-Inductance-Resistor-LCR-Meter-NPN-PNP-MOSFET-Vp-/171398863775?pt=LH_DefaultDomain_0&hash=item27e82b1b9f

[Silver Blues]

It would be great if it were, that's a great price.

[rocket88]

agreed

[IvIark]

I was going to get a new DCA75 but saw these a few weeks ago and thought I'd hold off until someone I know got one, to see what measurements it can make for FETs.  Still looks a bargain at that price though for someone who want a more specialist meter than a bog standard multimeter

[rocket88]

holy crap mark. i just looked up the DCA75, i didn't even know it existed, it doesn't seem like a huge upgrade from the DCA55. i got to say though, being in the US the fact that it connects to a computer for updates, and such makes me really want to get it, plus the image is a little nice.

the one thing they need to change imho is the test leads. i had to fix 2 of mine since i got it in july, the wires were weak and broke inside the clip, i had to resolder them.

[Beaker]

I noticed a whole bunch of these popping up on eBay a few months ago, mostly from China. I almost got one, but decided to hold off as most of them look a bit flimsy - I figured I would wait and see if they started to be mentioned on the forums, to try and gauge if they were woth it or not.

They are stupidly cheap though, and if they work well have to worth a punt.


I like the graphic display on these too.

http://www.ebay.co.uk/itm/New-12864-LCD-Transistor-Tester-Diode-Triode-Capacitance-ESR-Meter-MOS-PNP-NPN-/310926868734?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item4864af80fe

[IvIark]

rocket88 wrote

it doesn't seem like a huge upgrade from the DCA55.

It's the JFET testing that makes me want one, I like the idea of being able to match them at a touch of a button without having to dig out circuits to use and Excel spreadsheets.  If these cheaper ones will do it I'll be happy about that

[rocket88]

IvIark wrote

rocket88 wrote

it doesn't seem like a huge upgrade from the DCA55.

It's the JFET testing that makes me want one, I like the idea of being able to match them at a touch of a button without having to dig out circuits to use and Excel spreadsheets.  If these cheaper ones will do it I'll be happy about that

i missed that. now knowing that, that is a huge upgrade since the DCA55 only tells you the gate location on jfets. i'm going to have to keep an eye on them and see if i can get one for less then $180USD. will be really nice since all the jfet layouts that have been posted

[Heath]

I have one.  It's damn neat in that it's a one stop tester for resistors, capacitors, most transistors (pinout display is nice), diodes (+ it lights up LEDs when it tests which is a little bit useful), etc.

HOWEVER, it does not seem to properly recognize germanium transistors nor does it work right with Jfets in my experience.  I will post some examples when I get home from work.  THIS was the disappointing part for me.  Still, for about $25 it's a super neat little item to have.

[Kinski]

Heath, what do you mean it does not recognize germanium transistors? It wont read the HFE? Or the HFE reading is wrong?

[Heath]

It's been a few weeks, but if I recall (and I will test this as soon as I get home (in about 5 hours) if I put it in one way (ie. EBC) it would say "Damaged or no device" or something like that, where it SHOULD identify the leads and calculate/display accordingly.  Place the opposite way (ie. CBE) it would display what, if I remember right, did NOT match the measurements done by myself (slight risk of user error) or some others I've bought from (very very small chance of error).

I'll test some known value germs and several flavors of jfet when I get home and post my findings.  

Here's the one I bought (with the larger screen), which should have as updated a software version as any others you'd buy right now:





And here is the description text;

New 12864 LCD Transistor Tester Capacitance ESR Meter Diode Triode MOS NPN LCR

2014 latest M328 version of the software ,more functions.Chip: Atmega328
128*64 big Backlight LCD display,only 2mA when stand by.
Using 9V battery (Not inlcuded)  
NEW Function:
1:Automatic detection of NPN and PNP transistors, n-channel and p-channel MOSFET, diode (including double diode), thyristor, transistor, resistor and capacitor and other components
2: Automatic test the pin of a component, and display on the LCD
3:Can detect the transistor, MOSFET protection diode amplification coefficient and the base to determine the emitter transistor forward biased voltage
4: Measure the gate and gate capacitance of the MOSFET threshold voltage
5:Use 12864  liquid crystal display with green backlight
Size:140*90*55MM
Specifications:
1,One -button operation, automatic shutdown .
2,Only 20nA shutdown current.
3,Automatically detect NPN, PNP bipolar transistors , N -channel and P -channel MOS FET, JFET , diodes , two diodes, thyristors small power unidirectional and bidirectional thyristor.
4,Automatic identification components pin arrangement .
5,Measuring bipolar transistor current amplification factor and base - emitter threshold voltage.
6,Via the base - emitter threshold voltage and high current amplification factor to identify Darlington transistors.
7,Can detect bipolar transistors and MOS transistors protection diodes.
8,Measuring the gate MOS FET threshold voltage and the gate capacitance.
9,Can simultaneously measure two resistors and resistor symbol is displayed. Displayed on the right with a decimal value of 4 . Resistance symbol on both sides shows the pin number. So you can measure the potentiometer. If the potentiometer wiper is not transferred to an extreme position , we can distinguish the middle and both ends of the pin.
10,Resistance measurement resolution is 0.1 ohms , 50M ohms can be measured .
11,Can measure capacitanceCan measure capacitance of 30pF-100mF , resolution 1pF.
12.2uF more capacitors can simultaneously measure the equivalent series resistance ESR values. The two can be displayed with a decimal value , resolution 0.01 ohms.
13,Can be in the correct order and the diode symbol display two diodes , and gives the diode forward voltage.
14.LED is detected as a diode forward voltage higher . Combo of the LED is identified as two diodes.
15,Eeverse breakdown voltage is less than 4.5V Zener diode can be identified.
16,Can measure a single diode reverse capacitance. If the bipolar transistor connected to the base and collector or emitter of a pin , it can measure the collector or emitter junction reverse capacitance .
18 can be obtained with a single measurement rectifier bridge connection.
Notice: Before measuring capacitance , the capacitor must be discharged , otherwise very likely damage the meter .
Package Include:
1 x New 12864 LCD Transistor Tester Capacitance ESR Meter Diode Triode MOS NPN LCR (not include the battery)

[IvIark]

Thanks for the info buddy

[Heath]

Got totally sidetracked after work.  Here's some, hopefully, good info.  Beware, long and lots of (bad) pictures (please excuse the typos, I'm tired):

Seriously, pardon the shitty pictures.  Cell phone, Doritos fingers on screen protector, and an uncooperative overhead desk lamp *sigh*

NPN Si BJTs seem to measure fine
2n5088:


2n5133:


PNP Si BJT, no problem
2n3906:


A Darlington measures normally
MPSA18:


From here down I will limit my editorializing as I am quite stupid about a lot of this.  I'll point out glaring obvious weirdness, though.  For most of these I've measured them then flipped and measured them again.  On the ones where the transistor is difficult to see I've either marked the flat side, or in some cases I've traced it when it was really hard to see.  For the metal can Germaniums, well, you'll have to take my word that I checked the pin-outs first and they actually do match up though you can;t see it.

NPN Germanium
MP38a (known hfe 67, about 200mA leakage):



PNP Germanium
2n404a (known hfe 195, about 80mA leakage):




Now for Jfets, where it gets wonky (or maybe I'm just dumb)
2n5952 (note that I simply flipped the transistor but the pin-outs don't match that, measurements still the same though):



2sk30a (flipped it and it still reads the same pin-out.  DON'T TRUST IT! ):



j201 (Fairchild from Tayda or Mammoth, I don't recall, Identifies as an NPN-BJT with a CEB/BEC pin-out... weird...):



j201 SMD (got these from Chromesphere from Australia (super nice dude), the device has the same issues reading it.  It's mounted one one of those tiny pcb adapters so you can't see the orientation, which is why I included the purple text for comparison):



2n5457 (pinout numbers vs. meanings seem to be incorrect when flipped, but it's late and I'm tired and jfets confuse me):




Now here's a mosfet for fun
2n7000 (correct me if I'm wrong, but I think this is measuring correctly):




So make of that what you will.  Even with the issues I'm seeing, it's a nifty little gadget for $25.  Showing the proper pin-outs was what I was really hoping for, so I'm a touch let down there.  It seems to do okay with Germaniums in that regard, regardless of my previous post, so THAT is handy, especially with the more obscure Russian ones.  

I REALLY wish it measured the Germanium transistors taking the leakage into account, but even without that, the numbers don't look spot on to me... maybe hand-warmth messed with that some.  When I initially tested them with the layout on this site I left them alone for a while before taking the measurements.  This time I tried to give them a little settle time, but less than before. Sorry, I'm tired, been a long arduous week at work.

If anyone wold like me to show how it measures anything else it's supposed to be able to measure, just let me know and I'll do my best.  Happy to help.

[Ross]

This circuit is actually a ripoff of an open-source hardware project that some German guys put out. They even did their own vero layout for it (in DIYLC, no less!) I built the vero version, and while a lot of readings were bang on, a lot were not even close.

I am ordering parts to build a second one with better accuracy. It would probably be cheaper by now to just buy one off eBay, but I'm treating this as an excuse to learn more about AVRs. Heck, it's a lot cheaper than a Peak.

http://www.mikrocontroller.net/svnbrowser/transistortester/Here's the link to the SVN to download the project files. Don't worry, everything's in English (I can't speak German either). There's even the DIYLC file if you want to try to make a better vero (theirs is pretty terrible!)

[Luke51411]

Regarding JFETs, aren't source and drain often interchangeable? That could account for some of the inconsistencies if that is the case. I've done the adapter boards for smd jfets and the mmbf5457 data sheet has source and drain as interchangeable on those.

[Kinski]

Got the Peak DCA55. Awesome!