Starterman
28-01-2016, 22:26
A friend alerted me to a natty little tester for checking transistors etc on Ebay.
I did a bit of research and found that the tester is based on a jolly clever public domain design by a chap called Karl-Heinz Kuebbeler and this paper details what it's all about:
http://www.avrtester.tode.cz/upload/ttester_en.pdf
I think the most cost effective and latest hardware/software version is this:
http://www.banggood.com/DIY-M12864-Graphics-Version-Transistor-Tester-Kit-LCR-ESR-PWM-p-986954.html
How could I resist buying from a shop called "Banggood"? :)
I also ordered the matching case (which has not yet arrived):
http://www.banggood.com/Supporting-Shell-For-DIY-M12864-Graphics-Version-Transistor-Tester-Kit-p-989949.html
Parts quality is fine and the critical 6 resistors are 0.1% tolerance and do indeed measure spot on using my Fluke DVM. They also included the 8 Meg crystal and a TL431AA 2.5V +/-0.5% reference from Wing Shing :eek: so at least they are aiming for decent accuracy.
http://s10.postimg.org/btli07hcp/IMG_0201.jpg
A couple of hours later:
http://s27.postimg.org/6bdvp96g3/IMG_0212.jpg
http://s27.postimg.org/bliugjqoz/IMG_0213.jpg
I haven't fitted the ZIF socket because I want to see how it can be used with the case, although I have added some J-hook leads which make it a lot easier to connect to larger components.
So what's it good for:
Identifying pinouts of transistors, diodes, FETs, JFETs ( noneed to worry which leads you connect where)
Transistor Beta at 5mA - much more useful that the uA my Uni-T DVM measures at. VBE and diode Vf.
Mosfet threshold voltages
Some indication of junction capacitances of transistors and if they are leaky
Decent idea of capacitor values and ESR ( I think the capacitance is quite accurate, but low values of ESR are perhaps a bit less so, I still trust my capacitance bridge more but it takes a lot longer to get readings). Good down to about 20pF or you can parallel with a known value to get some idea for even smaller caps.
Rough idea on largish inductor values - not sure how accurate this is, I need to measure some parts with a decent LCR bridge to determine this.
Good for measuring low value resistors (perhaps better than the Fluke).
What does it need:
Reverse battery protection (it's not that difficult to try to fit a 9V battery the wrong way round and then it will go bangforgood!)
Input protection and/or a cap discharger - again to avoid a banggood scenario.
Of course a proper piece of kit like the Peak DCA75 will do a more comprehensive job with transistors, but it is 5X the price and doesn't measure all the passive components like the AVR tester.
Overall, I am very impressed at the range of capabilities and decent accuracy of this piece of kit for ~£20. Recommended.
I did a bit of research and found that the tester is based on a jolly clever public domain design by a chap called Karl-Heinz Kuebbeler and this paper details what it's all about:
http://www.avrtester.tode.cz/upload/ttester_en.pdf
I think the most cost effective and latest hardware/software version is this:
http://www.banggood.com/DIY-M12864-Graphics-Version-Transistor-Tester-Kit-LCR-ESR-PWM-p-986954.html
How could I resist buying from a shop called "Banggood"? :)
I also ordered the matching case (which has not yet arrived):
http://www.banggood.com/Supporting-Shell-For-DIY-M12864-Graphics-Version-Transistor-Tester-Kit-p-989949.html
Parts quality is fine and the critical 6 resistors are 0.1% tolerance and do indeed measure spot on using my Fluke DVM. They also included the 8 Meg crystal and a TL431AA 2.5V +/-0.5% reference from Wing Shing :eek: so at least they are aiming for decent accuracy.
http://s10.postimg.org/btli07hcp/IMG_0201.jpg
A couple of hours later:
http://s27.postimg.org/6bdvp96g3/IMG_0212.jpg
http://s27.postimg.org/bliugjqoz/IMG_0213.jpg
I haven't fitted the ZIF socket because I want to see how it can be used with the case, although I have added some J-hook leads which make it a lot easier to connect to larger components.
So what's it good for:
Identifying pinouts of transistors, diodes, FETs, JFETs ( noneed to worry which leads you connect where)
Transistor Beta at 5mA - much more useful that the uA my Uni-T DVM measures at. VBE and diode Vf.
Mosfet threshold voltages
Some indication of junction capacitances of transistors and if they are leaky
Decent idea of capacitor values and ESR ( I think the capacitance is quite accurate, but low values of ESR are perhaps a bit less so, I still trust my capacitance bridge more but it takes a lot longer to get readings). Good down to about 20pF or you can parallel with a known value to get some idea for even smaller caps.
Rough idea on largish inductor values - not sure how accurate this is, I need to measure some parts with a decent LCR bridge to determine this.
Good for measuring low value resistors (perhaps better than the Fluke).
What does it need:
Reverse battery protection (it's not that difficult to try to fit a 9V battery the wrong way round and then it will go bangforgood!)
Input protection and/or a cap discharger - again to avoid a banggood scenario.
Of course a proper piece of kit like the Peak DCA75 will do a more comprehensive job with transistors, but it is 5X the price and doesn't measure all the passive components like the AVR tester.
Overall, I am very impressed at the range of capabilities and decent accuracy of this piece of kit for ~£20. Recommended.