Low cost differential scope probe purchase - Page 1
Forum section: electronics / testgear

author: (In)Sanity
author_rank: Regular Contributor
timestamp: December 20, 2015, 02:53:34 am
content: So working on switch mode supplies more often lately I was thinking it would be a good purchase choice to pick up a differential probe for my scopes.I noticed some of these on eBay in the $190 - $260 range (US).Edit: Link removed due to manufacturer website being infected.Does anyone have any experience with this product? Does anyone have any price comparable alternative probes ?I have an isolation transformer, would prefer the extra piece of mind of having differential probes (real ones, not the scope trick).Thanks,Jeff

author: tautech
author_rank: Super Contributor
timestamp: December 20, 2015, 09:28:53 am
content: Quote from: (In)Sanity on December 20, 2015, 02:53:34 amThey might be worth checking out.Shall we nominate you to do the first EEVblog review?Most are quite happy with DP's from the Pintek (Taiwan) range.http://www.pintek.com.tw/product_classify/landersound-tail/index.php?Product_Site_Classify_SN=17072&Company_SN=6002

author: miguelvp
author_rank: Super Contributor
timestamp: December 20, 2015, 10:59:08 am
content: Or use two channels with the ground leads removed and using A-B if your scope can do math operations.On modern DSOs it's a bit slow but it will get the job done.Edit: as long as both signals have a common earth to the scope's earth.

author: nctnico
author_rank: Super Contributor
timestamp: December 20, 2015, 01:31:29 pm
content: I'd ditch the isolation transformer and get an extra GFI (ground fault interrupter). An isolation transformer does more harm than good because it is easy to create a ground path to the circuit and make it lethal without knowing it. IIRC Tektronix has a good paper on the subject of measuring mains attached circuits safely.Regarding a differential probe: there are many for sale on Ebay and they all are more or less the same. Personally I prefer one with a mains adapter so it doesn't need batteries.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 20, 2015, 03:03:43 pm
content: Quote from: (In)Sanity on December 20, 2015, 02:53:34 amQuote from: miguelvp on December 20, 2015, 10:59:08 am

author: (In)Sanity
author_rank: Regular Contributor
timestamp: December 20, 2015, 05:56:00 pm
content: Thanks for the replies, I must say the isolation transformer always leaves me a bit on edge. That stray USB cable on the bench with it's grounded connector bumping the DUT, stupid stuff like that. I have a Tek 2465B and a Rigol DS2302A, the Tek is a bit nicer to use with the differential probe trick, however from experience I don't care for that method on either scope.I've also been looking at rolling my own differential probe design (like many others). It's easy enough to get usable bandwidth, getting that flat is a little more difficult. I may just spend the cash and get the Instrance 100 Mhz model. Worse case it sucks and I can report my failure. Funny thing is sometimes you just want to see if a reasonable proximity of a signal exists vs spot on accurate. I've also had some luck powering some (not all) switchers from isolated DC, depends on the APFC. I don't recommend that either.Thanks,Jeff

author: mtdoc
author_rank: Super Contributor
timestamp: December 20, 2015, 06:22:50 pm
content: Since you have a classic Tek scope, why not consider a Tek p6046?You can usually find a decent one on eBay for about $100.Of course you could use it with your Rigol as well, though it might curse under its breath as you connected it...

author: vk6zgo
author_rank: Super Contributor
timestamp: December 21, 2015, 12:23:28 am
content: Quote from: (In)Sanity on December 20, 2015, 02:53:34 amWhen I tried the link,AVAST yelled at me & wouldn't let me go there!

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 21, 2015, 02:42:36 am
content: Quote from: vk6zgo on December 21, 2015, 12:23:28 amso is me... the site is infected with some virus script. i've not been able to catch the script name since the site is now totally blocked from me, in contribution by the avast..,edit: here it is (attached) i got it by trying different root branch...

author: (In)Sanity
author_rank: Regular Contributor
timestamp: December 21, 2015, 03:13:09 am
content: Quote from: vk6zgo on December 21, 2015, 12:23:28 amWell that's no bueno, I used one of the free online scan programs to scan their site:Website Malware MW:IFRAME:HD202?v02http://www.instrance.com.cn/( View Payload )Website Malware MW:IFRAME:HD202?v02http://www.instrance.com.cn//Index.asp( View Payload )Website Malware MW:IFRAME:HD202?v02http://www.instrance.com.cn//DownList.asp( View Payload )Website Malware MW:BLK:2http://www.instrance.com.cn/( View Payload )Sorry about all of that. Going to remove the link from my original post.Jeff

author: tautech
author_rank: Super Contributor
timestamp: December 21, 2015, 03:56:31 am
content: Quote from: (In)Sanity on December 21, 2015, 03:13:09 amAnd you wouldn't send them an email to tell them so?None of the 3 AV's on my PC reported a problem.

author: (In)Sanity
author_rank: Regular Contributor
timestamp: December 21, 2015, 04:16:45 am
content: Quote from: tautech on December 21, 2015, 03:56:31 amI thought about it, hard to actually reach anyone who would read an email, take it seriously and do something about it. Now add language barriers and it just gets more futile. With any luck they'll look at reviews on their products and land here, actually more likely then someone reading an email.Jeff

author: tautech
author_rank: Super Contributor
timestamp: December 21, 2015, 04:27:48 am
content: Quote from: (In)Sanity on December 21, 2015, 04:16:45 amFair enough, yet if you made a direct inquiry as a genuine buyer (you are) and relayed you lacked confidence in them as a result of your AV red flag, i'm sure they'd take note and jump through hoops to assist you.