I'm fluent in that and gibberish

I take it that is the case with some analog multimeters and not all multimeters because it seems a bit of a wierd thing to do and I'm not exactly sure why you would do that. When I connect my red probe to be delivering voltage and current that is exactly where I expect it to be coming out of, not switching around. It would actually be a very bad design the more I think about it now, all it would do is add to confusion.

when the transistor is not in a powered circuit there is no voltage to measure but since the base to emitter and collector behave like diodes, the diode check can be used and the meter provides the power for that. if I was using continuity mode I was just checking to see if the transistor has a short circuit and if it does there would still be no voltage to measure if it were powered up.

if you read the paragraph called “function” on this Wikipedia article a few times it might help explain it. en.wikipedia.org/wiki/Bipolar_junction_transistor it all has to do with the physics of the transistor geometry such as the base area being thin and the emitter being more heavily doped with charge carriers and how electrical momentum can be created to allow current flow between the emitter and collector.

One way to tell the difference is if there is different behaviour when shorting the possible drain with gate compared to shorting possible source to gate. The gate-source voltage is what controls the conducting channel, where zero volts (a short) from gate to source will open the channel and give low drain-source resistance. So if we measure low drain-source resistance with gate to pin A but then high resistance when shorting gate to pin B, then pin A must be source because we were able to open the channel.

I have some 30+ year old ceramic disc capacitors that have the exact value stamped on it like "0.1uF" and I thought that was like finding a unicorn. I'm afraid to use it in a breadboard in case I break the leads

@@GadgetReboot lol. Maybe stick them in real bread, then don't forget to take themout and put them into a fresh loaf before it hardens, otherwise you'll break the legs off! Seriously though, I do find the world of electrics electronic magnetism, you name it, bleeding confusing. Universal system??? It doens't exist, that would be too simple. Make a farad huge, that way we'll be dealing with millionths of em, make an amp enourmous, that way when 2 kills someone it'll seem less serious., don't label transistors as that would be telling. Call an amp I, after intensity, just in case anyone was getting to grips with it. It's a bit like yOutube, don't allow viewers to watch the video as they scroll the comments as that would be useful. But then youtube/ google have just dropped the bomb on Blogger. It wasn't broken, so of course they 'fixed it' with a new version that's 'mobile friendly'. Show me the moron that writes 2000 words blog posts on his mobile phone (while walking through traffic, or a park, or at 'work') and I'll show you 2000 words of crap. Great old user platform, dumped for some simpistic moron useful crap. No labels on transistors, tu m'etonne(what a surprise! Take it easy dude

sometimes the component does need to be removed from a circuit to test properly because other things can interfere with measurements.

I haven't worked with JFETs enough to have direct experience observing failures and all the sources I have seen refer to "a few hundred ohms" as normal with gate source connected, so it seems subjective but 550 ohms sounds close enough to good. I think a bad one would more likely have damage on the gate from excessive voltage, so if the diode check works, I'd say it's all good.

@@GadgetReboot Thanks for your swift response.

A couple hundred ohms is normal when the fet channel is fully conducting, so as long as it goes up very high toward infinite resistance when the channel is closed, it would seem to be working fine.

@@GadgetReboot thanks. You are a scholar and a gent.

emitter and collector aren't interchangeable

I just watched the other video and he said NPN gets a reading with positive on the base while PNP gets a reading with negative on the base. But his transistors have different pinouts with the base on the end instead of center pin.

Thank you so much. I was losing my mind trying to figure out which was correct. @@GadgetReboot

The easiest thing would probably be to get another meter, even $10 or less on Amazon I have seen a meter that not only does diode check but it also directly can test certain transistors at least NPN and PNP.

i’ve never seen the part number before but it looks like a general purpose NPN that can be replaced with other general purpose, the ones commonly available to me are 2N2222 and 2N3904. of course use the information at your own risk but that’s the best information I can find on those numbers. envirementalb.com/c945-transistor-pinout/

if it’s blown so that it’s got open or short connections then measuring it won’t work but if you can see the markings then you can try to look up various codes. There’s a lot of different websites about surface mount component markings like alltransistors.com/smd-search.php for through hole parts this might help www.qsl.net/yo5ofh/doc/transistor_codes.htm

when measuring the resistance between drain and source, when the gate is floating the resistance is probably going to be very high up in the megs, but when measuring the resistance drain to source and gate is also shorted to the source, it’ll be lower resistance, in this case it was a couple hundred ohms. So which ever pin shorted to the gate leads to a lower resistance reading from drain to source, that pin that’s shorted to the gate must be the source.

But how we can say that it's source or drain?

if you don’t know what any of the three pins are, you do the diode test to figure out where the gate is because it will have a diode drop from that pin to the other two pins. when you know which pin is the gate, measure resistance across the other two pins which will be source and drain, and do it while connecting the gate to one of those pins and then the gate to the other of those pins. when you see the lower resistance reading, the pin connected to the gate at that time is the source pin.

Thanks a lot 👍👍

If it's a general circuit, substituting might work as mentioned near the bottom of this page where a bunch of common part numbers are mentioned for substituting www.muzique.com/lab/splitter.htm

@@GadgetReboot its a peizo pre amp.. alexrice peizo pre amp..if u take a look www.zachpoff.com/resources/alex-rice-piezo-preamplifier/ Thankyou for reply

they are different in enough ways to be considered unique more than interchangeable.

One day I aspire to have an elaborate multi camera setup and better video editing skills