I have a Fluke 75 that has been totally reliable for years - which is a preface to saying I have no idea about current offerings... I am looking for a DVM for matching transistors. I have a bench supply that will provide a constant current and my fluke will display to .001V and give a repeatable stable reading, but I wanted a bit more resolution.
I did buy an Aicevoos 6000 count meter but it appeared to function like an underdamped random number generator. So it went back.
Any recommendations for something <$80?
cheers
I did buy an Aicevoos 6000 count meter but it appeared to function like an underdamped random number generator. So it went back.
Any recommendations for something <$80?
cheers
That Fluke is hard to beat.. although this is not the best method to match transistors. You need a curve tracer. I think there are PC based DIY devices.
It’s always good to include more info, as in what is the application and what devices are involved. All I’ve ever used is a fluke 37 in diode test mode to test and compare Vbe.
Maybe take a look at the PEAK DCA 75:
https://www.peakelec.co.uk/acatalog/dca75-dca-pro-semiconductor-analyser.html
That one is easy to use and offers some good functionality, though not cheap. Still way cheaper than a real curve tracer.
Downside: It is flimsy, and of course it will only test low voltage/low current. So not the right thing to match power transistors.
https://www.peakelec.co.uk/acatalog/dca75-dca-pro-semiconductor-analyser.html
That one is easy to use and offers some good functionality, though not cheap. Still way cheaper than a real curve tracer.
Downside: It is flimsy, and of course it will only test low voltage/low current. So not the right thing to match power transistors.
I really do not know why folks spend so much time and expense on matching bjt's, to me it's a 10 second operation, if at all needed.
Today the devices are so much alike and who matches NPN to PNP? Just maybe for some open loop app where you want the lowest of thd or other parameters.
I do select/match lsk489 and lsj689 for DH-220C but that's done in circuit with bias I adjusted by a pot, full supply V.
Today the devices are so much alike and who matches NPN to PNP? Just maybe for some open loop app where you want the lowest of thd or other parameters.
I do select/match lsk489 and lsj689 for DH-220C but that's done in circuit with bias I adjusted by a pot, full supply V.
The old Fluke is fine for the vast majority of everything I do and totally reliable thus far.
I want to match using my bench supply at 200mA and I want at least two sets of three from a pool of 50+ devices. I am led to believe that it might be possible to get matches of Vgs to 3 decimal places. I am not in a hurry and have a big heatsink.
I'd also like to have a second DVM so that I can hook two simultaneously when adjusting bias and offset
-so I want a second one and it may as well be better.
(and thanks)
I want to match using my bench supply at 200mA and I want at least two sets of three from a pool of 50+ devices. I am led to believe that it might be possible to get matches of Vgs to 3 decimal places. I am not in a hurry and have a big heatsink.
I'd also like to have a second DVM so that I can hook two simultaneously when adjusting bias and offset
-so I want a second one and it may as well be better.
(and thanks)
I bought a Brymen BM235 (the EEVBlog one, as it happens) a few years back and have been quite pleased with it. It's not quite as nice as my Fluke 189, but I also don't feel nearly as bad about carrying it in my backpack. If I had to recommend a DMM to someone, that would be it. I have yet to find a sub-$100 meter that isn't hot garbage. If I had to spend less, I'd buy something used on eBay.
If you want to match transistors, you need a curve tracer. The PEAK Atlas still only measures current gain at one operating point. Even the cheap $40 kits on eBay are acceptable, and there are a few pretty decent DIY designs here and on the EEVBlog forum. The gold standard is a Tektronix 576 or a pair of Keithley 2400 source meters.
That said, I usually try to design my amplifiers such that transistor matching isn't critical, because matched transistors = manufacturing nightmare, and if it really matters then you probably want them to be on the same die anyway. I have a 576, and it honestly gets used about twice a year (it's a good thing it's so darn cool looking, because it sure takes up a lot of bench space for how often it gets used).
If you want to match transistors, you need a curve tracer. The PEAK Atlas still only measures current gain at one operating point. Even the cheap $40 kits on eBay are acceptable, and there are a few pretty decent DIY designs here and on the EEVBlog forum. The gold standard is a Tektronix 576 or a pair of Keithley 2400 source meters.
That said, I usually try to design my amplifiers such that transistor matching isn't critical, because matched transistors = manufacturing nightmare, and if it really matters then you probably want them to be on the same die anyway. I have a 576, and it honestly gets used about twice a year (it's a good thing it's so darn cool looking, because it sure takes up a lot of bench space for how often it gets used).
I recently bought an excellent UNI-T UT61E+ because it's True RMS ability has an extended frequencey range. (40-10kHz)
www.amazon.co.uk/UNI-T-Digital-Multimeter-Resistance-Capacitance/dp/B08NDLYLY3
Can't fault it.
www.amazon.co.uk/UNI-T-Digital-Multimeter-Resistance-Capacitance/dp/B08NDLYLY3
Can't fault it.
I matched a whole bunch of J113s with a bench supply and a Flir DM62 DMM. Looks like it is occasionally under USD$80 depending on where you look. I certainly paid a lot more over here a few years back. It's not the most full featured thing, but it's 6000 count and pretty solid. I have no complaints. Nice stock leads.