"New Pro" Differential Probe - Page 1
Forum section: electronics / testgear

author: djacobow
author_rank: Super Contributor
timestamp: March 05, 2015, 01:35:55 am
content: Does anybody have one of the "New Pro" HV differential probes as seen on E-bay? They are in the $210-290 range. I'm tired of floating my scope; I'd rather have proper gear -- well, sort of proper. Accuracy and bw are not that important to me (25 MHz) but safety and convenience are. Mostly for US 110 AC work.http://www.ebay.com/itm/New-Pro-Differential-probes-DC-25Mhz-Max-Voltage-1300V-Tektronix-OEM-Taiwan-CAT3-/300710178863?pt=LH_DefaultDomain_0&hash=item4603b9302f-- dave j

author: grantbob
author_rank: Unknown
timestamp: March 05, 2015, 01:43:49 am
content: I don't know much about them but that one is also listed often as Pintek and seems to be an exact match for what Rigol sells as their RP1025Dhttp://www.rigol-uk.co.uk/Rigol-RP1025D-High-Voltage-Differential-Probe-p/rp1025d.htm#.VPez-WZrXX8Looks like there's a teardown and some more info here:https://www.eevblog.com/forum/testgear/teardown-pintek-dp-25-differentail-probe/I'd also be interested in opinions on this one.-grantbob

author: nctnico
author_rank: Super Contributor
timestamp: March 05, 2015, 01:48:59 am
content: I have bought this one a couple of years ago. It works OK (it does what it needs to do). What I like about it is that is uses a main adapter so no messing with batteries.

author: ElektroQuark
author_rank: Unknown
timestamp: March 05, 2015, 07:49:15 am
content: You can buy itHEREfor 175€, shipping included.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 05, 2015, 10:59:55 am
content: Bit of a design fail that it needs a seperate PSU instead of using the USB power available on most scopes - looks like only 35mA so a small DC-DC would do the trick, but really should have been built in

author: electr_peter
author_rank: Unknown
timestamp: March 05, 2015, 11:12:08 am
content: Looks very interesting. As for power source, it requires only 9V at 35mA for internal DC/DC converter. So any isolated DC/DC power module will do - there are variants with 5V in/9V out at ~1W max.Question is, can you use non isolated power source (like boost converter from 5V USB)?

author: codeboy2k
author_rank: Super Contributor
timestamp: March 05, 2015, 11:37:28 am
content: Quote from: electr_peter on March 05, 2015, 11:12:08 amIf it's done right inside, it would have to cross the isolation boundary with isolated power. So that 9V input is already going to be isolated from the probe side, which means all the more fail, since they really really could have used the USB power from the scope to power this, as Mike said. Every single Rigol scope has a USB port on the front.If their decision was based on wanting to sell to users of other scopes, that might not have USB ports, then they can provide a 5V USB charger type wall wart instead of the 9V barrel adapter, and a removable cable for the wall wart, and that cable can also go into the Rigol front port.

author: nctnico
author_rank: Super Contributor
timestamp: March 05, 2015, 04:00:50 pm
content: The idea of using a DC-DC converter is nice. Perhaps it would even fit in the existing housing. Then again a DC-DC converter would need some serious filtering because the output is far from noise free. I usually put a 330uf electrolytic at the output to start with. For anything analog I also throw in a common mode choke and some ceramics.Then again.. where do you plug your USB stick when the USB port is occupied?

author: djacobow
author_rank: Super Contributor
timestamp: March 05, 2015, 07:11:13 pm
content: Thanks, everyone. I think I'm going to go with the B&K PR-60, as I actually prefer batteries over one more wire hanging out of my setup. Mike is right that a USB-powered unit would have been cool.One thing I like about this unit is that it has a 10x mode. As it happens, some of the signals I'm measuring riding on 120V are smallish themselves.-- dave j

author: grantbob
author_rank: Unknown
timestamp: March 06, 2015, 12:11:26 am
content: Quote from: djacobow on March 05, 2015, 07:11:13 pmLet us know how you like it. Also note when shopping that that one appears to be the same as the Cal Test CT2593-2 and it looks like TPI and Teledyne LeCroy also have similar ones (not sure if all the specs are the same.)-grantbob

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 06, 2015, 12:40:46 am
content: I just ordered one of the ebay ones to investigate...

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: March 06, 2015, 01:16:24 am
content: Hi,If it is the same design as the probe in this thread:https://www.eevblog.com/forum/testgear/teardown-pintek-dp-25-differentail-probe/Then this section of the board looks very much like a dc / dc converter. It looks like it generates +/- rails from the input. It is shame that requires 9V and doesn't work from 5V (USB).Jay_Diddy_B

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: March 06, 2015, 01:24:20 am
content: Hi,I made some measurements on similar probes in in this thread:https://www.eevblog.com/forum/projects/high-voltage-differential-probe-design-for-review/msg600694/#msg600694I found that input capacitance and inductance of the leads from an undesirable resonance. It looks like the Pintek probe has the same issue. A resistor of about 500 Ohms in series with the leads is an effective way of supressing the resonance.Jay_Diddy_B

author: nctnico
author_rank: Super Contributor
timestamp: March 06, 2015, 01:38:14 am
content: I opened mine. There is a DC-DC converter circuit indeed which makes a whole bunch of voltages (it's not very accurate BTW). It switches on with a 5V power supply but it's hard to tell the supply voltages are sufficient.

author: commongrounder
author_rank: Frequent Contributor
timestamp: March 08, 2015, 06:19:12 pm
content: Quote from: grantbob on March 06, 2015, 12:11:26 amAll of the above units are based on the SI-9000 series probes made by Sapphire in Taiwan (although apparently there have been some Chinese clones). I have two of them and they run on 4 AA batteries. The low batt light comes on just at 4.7 volts, so it seems feasible that they could work from USB power directly. I'll have to try that out.