The world easiest, cheapest, and NOT safety way to have an isolated oscilloscope - Page 1
Forum section: electronics / testgear

author: gamalot
author_rank: Super Contributor
timestamp: March 31, 2016, 03:35:48 pm
content: When you have this Rigol 1000Z oscilloscope and a bench power supply (How is my English?)

author: nctnico
author_rank: Super Contributor
timestamp: March 31, 2016, 03:51:45 pm
content: Bad idea because it leaves many metal parts of the scope free to touch. Also the isolation of the power supply may be less than you think!

author: tggzzz
author_rank: Super Contributor
timestamp: March 31, 2016, 04:24:42 pm
content: Istronglysuggest you read the two safety references in the "high voltage" subsection ofhttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/They show you what's safe(which is relatively unimportant), and everybody else what is safe (which is more important).

author: gamalot
author_rank: Super Contributor
timestamp: March 31, 2016, 04:37:20 pm
content: Quote from: nctnico on March 31, 2016, 03:51:45 pmQuote from: tggzzz on March 31, 2016, 04:24:42 pmYes, you are right, thanks for all your advice.I am not gonna use it to test any high voltage, I was just feeling happy that I've found the way to test my isolated device, cuz I don't have any isolation transformer or probe

author: gamalot
author_rank: Super Contributor
timestamp: March 31, 2016, 04:43:58 pm
content: I've changed the topic toThe world easiest, cheapest, and  safety way to have an isolated oscilloscope

author: nctnico
author_rank: Super Contributor
timestamp: March 31, 2016, 04:57:25 pm
content: A couple of months ago I built an instrumentation amplifier box using the AD8421BRZ amplifiers powered from +/-15V to allow measurements with the 0V level floating a couple of volts above or below ground. I made the input impedance 1M Ohm so I can also use a regular 1:10 probe with it.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 31, 2016, 05:29:12 pm
content: Quote from: gamalot on March 31, 2016, 04:43:58 pmyou can cover any exposed metal with tape. if that is not enough, find broken Fluke 87V in dumbster and cut the plastic case to shape, and cover the dso exposed metal part with that, such as usb ports, cal output etc. as for protruding BNCs port, make sure probe always intact, (not exposed metal bnc male endpoint, the original rigol probe), and then mod your probe tip like in the attached. that should give you some level of "safety" (if you have a bit of common sense and dont exceed differential input limit of the probe/dso input). if someone tells you that it is not safe, then what they are trying to say is actually that:1) you are not up for the task.2) they are not confident of your skills and competency.if you are up for the task and they still tell you its not safe, then the industrial Fluke 87V is equally unsafe. but if you are not, then you should concern of yourself more than what you are trying to do, even if you have Fluke 87V at hand.

author: gamalot
author_rank: Super Contributor
timestamp: March 31, 2016, 05:52:51 pm
content: Quote from: Mechatrommer on March 31, 2016, 05:29:12 pmI don't really understand why should I cover all exposed metal with tape, I don't think I am doing anything more dangerous than touching exposed metal on my USB charger ......

author: mmagin
author_rank: Frequent Contributor
timestamp: March 31, 2016, 05:54:26 pm
content: I bet you could sell one of those nice power supplies and get an isolation transformer and have a lot of cash left over.(Not that an isolation transformer is a magic ticket to safety either -- you still have to know what you're doing and proceed with caution.)

author: gamalot
author_rank: Super Contributor
timestamp: March 31, 2016, 06:08:50 pm
content: Quote from: mmagin on March 31, 2016, 05:54:26 pmYes, I will buy myself a good isolation transformer once I got the money from my wifehere is the spec of my power supply, I think 240V is enough in this case - to test another isolated programmable dc power supplyIsolation Voltage, Output to Chassis:Any output can be floated up to 240V (DC + peak AC with AC limited to a maximum of 3Vpk-pk and a maximum frequency of 60Hz) relative to earth ground terminal.Isolation Voltage, Output to Output:Any output can be floated up to 240V (DC + peak AC with AC limited to a maximum of 3Vpk-pk and a maximum frequency of 60Hz) relative to any other output terminal

author: gamalot
author_rank: Super Contributor
timestamp: March 31, 2016, 06:23:01 pm
content: What I am trying to do is to repair this Keithley 2306 battery simulating DC power supply, I had found out and fixed 2 problems, but there is still something wrong with the output channel 1 on the analog board

author: gamalot
author_rank: Super Contributor
timestamp: March 31, 2016, 06:47:30 pm
content: Look at the analog board, it's too complicated to me! Please help! Dose anyone have the schematics of Keithley 2306?