30$ JYEtech scobe from ebay: What can it do? MEASURE MAINS!!!! - Page 1
Forum section: electronics / beginners

author: Beamin
author_rank: Super Contributor
timestamp: July 25, 2018, 12:56:12 am
content: I got a few of these mainly because the first two magically self destructed and the screen just would boot up white. Dave did a video on it and every other electronics youtuber.But not wanting to break my last one:Can I measure things like power supplies with the "probes" (alligator clips to BNC) it came with; no A/C filter like putting a cap for protection? Does this act as a low impedance device where it will just short my lab power supply out and kill the scope?Would it be saved if I run a real 10/100X probe on it? Or a 1m resistor in series on it? I have a whole bunch of little power supplies I found and would like to see how clean they are then connect some power resistors and compare. Could be use full for quick and dirty measurement where you don't want to lug around a scope.What the most voltage a scope can take? I never see those specs but I guess it's not a single answer or they just assume you know what you are doing. I'm still hesitant to burn up my tek 3365? scope from the 80's. I did only pay $100 for it, but thats $400+ to replace. If I could learn on this little one it would be perfect.

author: lordvader88
author_rank: Frequent Contributor
timestamp: July 25, 2018, 09:47:14 am
content: Are you talking about a pocket scope like a DSO138 ? Yeah IDK what the highest input voltage is, but it's not that high, maybe 50V.They work fine with 10x probes on RECTIFIED 169V from 120VAC, I think I used it on 320VDC from the PFC stage of a computer PSU.I never bothered to try probing before the rectifier tho so IDK, but with 10x probes I 'think' it should handle it fine.

author: stj
author_rank: Super Contributor
timestamp: July 25, 2018, 12:43:18 pm
content: most probes only have insulation ratings of 300v btw.and that de-rates as the frequency increases too.

author: Beamin
author_rank: Super Contributor
timestamp: July 26, 2018, 12:02:09 am
content: Quote from: stj on July 25, 2018, 12:43:18 pmAs far as the impedance goes: it comes with alligator clip leads. Could I just connect them directly across a <20v power supply like I could a voltmeter?

author: Nusa
author_rank: Super Contributor
timestamp: July 26, 2018, 12:47:40 am
content: The specs for whichever model you have are listed on the appropriate page on the site:https://jyetech.com/Products/Oscilloscope.phpAlso links to documentation if you don't have it. Some of the counterfeits probably left it out.

author: Jwillis
author_rank: Super Contributor
timestamp: July 26, 2018, 06:00:55 am
content: Those DIY scopes are more a curiosity than a workable tool.I wouldn't trust them over a maximum of 50V DC.Mine starts to clip even at 30 Volts .Basically just toys .Have you considered a High Voltage Differential Isolating Oscilloscope Probe.If your concerned about high voltage that might be the safest bet.

author: Beamin
author_rank: Super Contributor
timestamp: July 28, 2018, 09:11:54 pm
content: So I just found the thermostat in my house runs on 24VAC could I use the alligator clips to probe what the different wires do (or rather look at the ac wave forms)? This wont hurt the scope or blow the fuse in the thermostat? Can I assume you can use it the same way you would a multimeter keeping in mind not to probe abouve 50 or 30 volts?If I use the alligator clip leads would it just look like a high impedance source so very little current would pass through it?I hate only having one of something I can't blow up by accident. I want to get comfortable with this device before I start using my tek scope.

author: Jwillis
author_rank: Super Contributor
timestamp: July 30, 2018, 06:08:08 am
content: Why don't you build a simple oscillator circuit with an inductor and capacitor.You can see the varying oscillations by changing the inductor or capacitor. And you can even predict what the resonant frequency is.Frequency in Hertz is f= 1/2pi√L*CYou can run your simple oscillator on a 9 volt battery

author: Beamin
author_rank: Super Contributor
timestamp: July 30, 2018, 11:23:36 pm
content: Quote from: Jwillis on July 30, 2018, 06:08:08 amJust the post I was looking for and it gives me an excuse to build something!I think next I'm going to attach the red lead of the scope to the tungsten tip of the TIG welder and the black lead to its ground turn the amps all the way up and see if the waveform distorts right when I turn it on. Or measure how clean the power from the stick welder when it's all the way up. Something tells me I should video tape this.