I have been planning to buy a proper multimeter for a while now and I am going to do so soon.
In one of his videos (can't remember which) Dave mentioned the fact that only cheap multimeters measure capacitance and BJT transistors. My meter is hopeless at measuring capacitance and transistors so I was thinking that before I invest money into a meter, perhaps I should consider buying a semiconductor tester specifically for the use of testing various transistors that I have. So I had a link bookmarked for a while now, perhaps a future project, which was this semiconductor tester using an ATMega8:
http://translate.google.com.au/translate?hl=en&sl=de&u=http://www.mikrocontroller.net/articles/AVR-Transistortester&ei=SQ-hT9TCKrG8iAfksunzBA&sa=X&oi=translate&ct=result&resnum=1&ved=0CCUQ7gEwAA&prev=/search%3Fq%3Dhttp://www.mikrocontroller.net/articles/AVR-Transistortester%26hl%3Den%26newwindow%3D1%26safe%3Dactive%26client%3Dsafari%26rls%3Den%26biw%3D1440%26bih%3D803%26prmd%3DimvnsfdI am thinking should I construct this or not? Perhaps it will be too much of a challenge for me, never done micro controllers, display and circuitry with so many connections!
So then I decide to visit eBay an come across three choices, a pure semiconductor tester, a semiconductor tester with capacitance and ESR, just an ESR meter. Below are a few examples of what I had found.
Semiconductor:
http://www.ebay.com.au/itm/Transistor-Semiconductor-Parameter-Tester-Meter-DY294-/230780280164?pt=LH_DefaultDomain_0&hash=item35bb939d64 Measures only BJT?
OR
http://www.ebay.com.au/itm/Semiconductor-tester-/221010495784?pt=LH_DefaultDomain_0&hash=item3375408928#ht_549wt_1378 Looks ugly!
Semiconductor and ESR:
http://www.ebay.com.au/itm/ESR-C-L-meter-tester-90-kHz-and-Semiconductor-tester-/221006233103?pt=LH_DefaultDomain_0&hash=item3374ff7e0f#ht_576wt_1378] [url]http://www.ebay.com.au/itm/ESR-C-L-meter-tester-90-kHz-and-Semiconductor-tester-/221006233103?pt=LH_DefaultDomain_0&hash=item3374ff7e0f#ht_576wt_1378[/url] Ugly.
ESR:
http://www.ebay.com.au/itm/ESR-meter-100KHz-capacitor-tester-repair-work-light-weight-low-voltage-AU-/290704946335?pt=AU_Electronics_Vintage_Electronics&hash=item43af5d749f#ht_2919wt_1378] [url]http://www.ebay.com.au/itm/ESR-meter-100KHz-capacitor-tester-repair-work-light-weight-low-voltage-AU-/290704946335?pt=AU_Electronics_Vintage_Electronics&hash=item43af5d749f#ht_2919wt_1378[/url] Looks cheap and poor quality?
OR
http://www.ebay.com.au/itm/ESR-Meter-Electrolytic-Capacitor-Meter-DC2-5x5-5-Blue-LCD-/130686906166?pt=LH_DefaultDomain_0&hash=item1e6d8bef36#ht_1644wt_1378 There is a separate thread about this one:
https://www.eevblog.com/forum/product-reviews-photos-and-discussion/esr-meter-teardown-hungarian-cottage-industry-unit-from-ebay/msg94219/#msg94219Are any of these good? I assume I may have posted some which are poor quality, but these are just the main ones that I could find. If anybody has anything else can they please recommend?
Now my final question, which I should of probably mentioned before is whenever this is a useful piece of equipment to have in a lab.
For the transistor tester, it is hard to beat the AVR based one. See the thread on it:
https://www.eevblog.com/forum/product-reviews-photos-and-discussion/semiconductor-tester-identifier-by-%27warf%27-internal-views/In general, if a transistor looks like two diodes on the diode range of your multimeter, it is almost certainly working. A MOSFET should look like a diode source to drain, and the gate is an open circuit.
Past that, you have to start looking at a curve tracer if you want useful parameters for devices. Alternatively, you set up a power supply or two with some resistors, and make a temporary test rig for the device under the operating conditions that you need.
I have been tempted by those high voltage tester, but the voltages are potentially dangerous, especially when you are voltage testing capacitors, and you can easily damage devices. Over 20V will instantly destroy a MOSFET gate, and when you check the breakdown voltage of capacitors, that will destroy the capacitors as well.
Richard.
Dangerous prototypes is working on a component tester based on Markus original design but I think they are expanding the features and already made a smaller PCB for it. It's called Part Ninja. Other people are modifying the original project as well and coming up with interesting ideas.
You can check them out:
http://dangerousprototypes.com/category/part-ninja/I purchased the semiconductor tester from warf.com on ebay. For the most part it works fine. It had some problems with the firmware so I had to download the original firmware from Markus and purchase a USBASP to reprogram the AVR processor.
So you guys recommend that I build one?
I have one of the Jaycar testers, it looks like a clone of the Peak braded ones. It can be found on special at times at around $50 Au. I think I paid $55 for mine, I love it works well for me.
I also have the Chinese Auye one as well, it has the ability to check 3 terminal regs and caps for breakdown voltage as well as zeners. it cost me about $60 from memory direct from China, I recommend it too, it complements the Jaycar one.
Regards,
Raff
For ESR meter I modified an 5 USD analog meter. Nothing special. I gives you an idea for the capacitor being checked.
Alexander.
For an ESR meter, I have an old but trusty Electronics Australia kit from Dick Smith Electronics. The kit is no longer available from DSE, but there was a revision done by Silicon Chip and a later kitset done. I think Altronics still do that kit.
Here is some info from the designer.
http://members.ozemail.com.au/~bobpar/esrmeter.htmRegards,
Raff
I will have a further look into the design of the ESR meter and perhaps try to construct it once I got everything together, its gonna be one big learning experience!
Here is a pretty good review of the DY294 semiconductor tester.
http://www.jestineyong.com/review-of-the-dy294-digital-transistor-tester-part-1/I bought one after seeing this review and how useful the tester would be for me. I'm forever trying to find out what voltage a zener is for example, and I can remember the number of times I have used it to test 3 terminal regulators.
Hey Dave, maybe you could review one for us? And of course a teardown! I love the teardowns!
Regards,
Raff.
There's a fork of the original transistor tester project on microcontroller.net too. The thread is
http://www.mikrocontroller.net/topic/248078 (German) and the SVN with docs and source code is
http://www.mikrocontroller.net/svnbrowser/transistortester (including an English version). The software is still under development but stable. I've just built a modified version with a PWM controlled backlight and adding features to the software. Maybe some of my modifications will end up in the project. The tester is a really nice project to play around with µCs :-)
If you just want to see if a BJT amplifies,for an NPN transistor ---With your DMM in diode test,connect the Red lead to the collector & the Black lead to the emitter.
You should see "OL" or something similar on the meter.
Now spit on your finger,& use it to connect between collector & base,& if the device is OK,you will see a low reading on the meter.
For a PNP,just reverse the meter leads.
Obviously,this doesn't give a definitive indication of transistor characteristics,but is a useful check.
If the idea of spit grosses you out,make a jig so you can connect between collector & base with a 2k resistor or similar.
Lots of people use this trick,but it is very seldom published,with most discussions just giving the "looks like 2 diodes" check.
To test transistors and MOSFETs I recommend Sencore TF-46, it meausre bias (go, no go) and leakage. You can get used one from eBay for around $40. These are old school very high quality meters that last forever. It also let you test gain for FETS as well as beta, you can identify pinouts and test transistors in circuit (go, no go only)
It also have a feature where you connect transistor and instrument emits sound, you can than twist pins and identify intermittent transistors (this is very rare, however, one you come across one that does that you will love this feature)
Mentioned meters are more to test and sort new components and they are not reliable to detect some defective transistors. (TF-46 was around $500 new)
For ESR it depends what you want to do with it, If you need meter for troubleshooting I recommend analog meter, its faster to work with, very good one is Capacitor Wizard, cheap alternative is MUL-3333 (around $40).
For digital ones make sure its resolution is at least 0.01R.
Casinada,
I have three of the WARF AVR based units. I wrote the original post on the units and they seemed pretty reliable but then I have not used them greatly due to recent ill health...please can you expand on what the firmware issues were and how I would go about changing teh firmware...is the WARF AVR locked in any way ? I am a virgin to AVR programming.
Many Thanks
Aurora
I have three of the WARF AVR based units. I wrote the original post on the units and they seemed pretty reliable but then I have not used them greatly due to recent ill health...please can you expand on what the firmware issues were and how I would go about changing teh firmware...is the WARF AVR locked in any way ? I am a virgin to AVR programming.
I don't think that the WARF AVR is locked, since the firmware is open source. The most inexpensive solution for programming is to build or buy a simple ISP tool supported by avrdude (free programming software). If you got an arduino you may use it as an ISP tool (there's a sketch for that). I'm using the BusPirate. It's a great tool anyway :-) In the pictures of the original post I haven't seen any ISP header, so you might add one if you plan to update the WARF AVR several times. It's more convenient than using clips or removing the ATmega every time.
For the ESR tester, I've owned an AnaTek Blue which is an update of the Dick Smith unit for about 3 or 4 years now. Great meter and has probably saved me a lot of time. Using it becomes second nature interpeting the numbers vs. cap size voltage with use. I also have an old Sencore LC-53 which is the last word in cap value and leakage. There are newer units with ESR and fancier features, but this one works great and can test up to 450V. I can't see a need for any others. The ones in the meters that I have are too limited. For transistors, for most all tests, in circuit performance tell quite a bit. Ohmeter verification usually follows out of circuit. I still have one of those old Radio Shack neon bulb go/no go testers that I've had for nearly 40 years. It's good for bulk sorting if you buy a batch. Somewhere I have an old B&K meter that I haven't used since the early 80's. I keep an "octopus" on top of my analog scope which functions as a basic curve tracer that I built about 30 years ago. Adding a BNC and a switch to allow a square wave input from a function generator instead of using the line transformer can make the octopus usable for deterimining ESR. I haven't done that, but it's an option if someone was on a budget. Having an octopus around is a very useful qualitative tester for caps and anything with a p/n junction. Shame that it's something nearly forgotten and it took someone to essentially package what I described above in a scope frame and call it a signature analyzer by Huntron and other companies. You can build one from almost nothing and just use your function generator as the signal source. In years of protyping and service, I've never seen the need for a formal curve tracer or waste my time with a meter like the B&K or the sencore mentioned above. You can see leakage with an octopus.
