Differential Probe - Reverese Engineered - Page 3

bading · 22nd April 2016, 04:57 PM

The ground circled in red are the same or the ground of the high voltage signal is isolated ?

ground.jpg

Thank's
Dario

underwurlde · 25th April 2016, 09:31 AM

Is the same (common) ground.

Mauby · 28th July 2016, 09:04 AM

Nice work!

I would like to build 4 of these for my works at home.

Do you have some pictures from the pcb, so that i could get an idea of the design ?

COSMOS2K · 12th October 2016, 01:38 PM

Excellent project and excellent reverse engineering.

Thanks for sharing.

Greetings.

Armadillo · 12th February 2017, 10:36 PM

Anyone has the BLM700 datasheet?

Calvin · 14th February 2017, 02:26 PM

Hi,

here´s an interesting DIY build of a Diff-Probe:
click here

jauu
Calvin

engenius · 7th April 2017, 06:20 PM

first of all I´d like to thank underwurld for sharing his work results.
I just bricked my SI-9000 (THT version) by accidently applying 30V revers voltage to the output when calibrating it :-(
The output buffer OP amp (U3) had gone. As the code had been sanded off and the part has quite some demanding specs, a suited spare wasn’t easy to find.
Some types mentioned in this forum (AD797, etc.) won´t probably work, because they use V+ instead of V- referenced offset adjustment.

After spending some time investigating, I figured out these typed:

AD817
AD847
LM6361
LT1357
LT1360
LT1363

All of these have at least 25 MHz bandwidth, 300V/µs slewrate and low noise. I will give the LT1360 a try because it´s availability and price (about 4 EUR/1) and its excellent specs.

In the meanwhile, I run the SI-9000 with a TL081 (crappy 100 kHz bandwidth)

emocabras · 10th April 2017, 09:42 PM

Hello I write from Italy, you very good great job reverse engineering.

probe power supply be your creation or integrated probe?

I can feed with different dual power supply 9v battery 500mah

resistors marked point have tolerance 1%?

What power Watts have resistances this circuit?

You can publish original probe picture layout component

Coyote973 · 25th July 2017, 07:34 PM

@underwurlde : Great post!

Perhaps adding a photo of other PCB side and how compensating capacitor are arranged (under resistor divider) would make even more clearer (if your device is still apart).

I took a look on schematics SMD type, but I think that R40 is somehow positioned in wrong way. I have searched many current mirrors, Wilson, Widlar,...any current mirror that exists, and haven't found any such mirror that has a resistor in that place.

The listed components are quite old and difficult to find. The U441 is now produced by Linear Systems. I wish I could understand the principles of the weird pair jfet + bjt.

AndrewT · 26th July 2017, 08:27 AM

Underwurlde,
Can you attach your pics now lost from posts 1 & 2?

14th February 2017, 02:26 PM	#26
Calvin diyAudio Member Join Date: Nov 2004 Location: close to Basel	Hi, here´s an interesting DIY build of a Diff-Probe: click here jauu Calvin __________________ My Website

7th April 2017, 06:20 PM	#27
engenius diyAudio Member Join Date: Apr 2017	U3 substitutes and spares first of all I´d like to thank underwurld for sharing his work results. I just bricked my SI-9000 (THT version) by accidently applying 30V revers voltage to the output when calibrating it :-( The output buffer OP amp (U3) had gone. As the code had been sanded off and the part has quite some demanding specs, a suited spare wasn’t easy to find. Some types mentioned in this forum (AD797, etc.) won´t probably work, because they use V+ instead of V- referenced offset adjustment. After spending some time investigating, I figured out these typed: AD817 AD847 LM6361 LT1357 LT1360 LT1363 All of these have at least 25 MHz bandwidth, 300V/µs slewrate and low noise. I will give the LT1360 a try because it´s availability and price (about 4 EUR/1) and its excellent specs. In the meanwhile, I run the SI-9000 with a TL081 (crappy 100 kHz bandwidth)

26th July 2017, 08:27 AM	#30
AndrewT R.I.P. Join Date: Jul 2004 Location: Scottish Borders	Underwurlde, Can you attach your pics now lost from posts 1 & 2? __________________ regards Andrew T.

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22nd April 2016, 04:57 PM	#21
bading diyAudio Member Join Date: Mar 2015 Location: Italy	The ground circled in red are the same or the ground of the high voltage signal is isolated ? ground.jpg Thank's Dario

25th April 2016, 09:31 AM	#22
underwurlde diyAudio Member Join Date: Feb 2005 Location: S.England	Is the same (common) ground.

28th July 2016, 09:04 AM	#23
Mauby diyAudio Member Join Date: Jul 2016	Nice work! I would like to build 4 of these for my works at home. Do you have some pictures from the pcb, so that i could get an idea of the design ?

12th October 2016, 01:38 PM	#24
COSMOS2K diyAudio Member Join Date: Jun 2016	Excellent project and excellent reverse engineering. Thanks for sharing. Greetings.

12th February 2017, 10:36 PM	#25
Armadillo diyAudio Member Join Date: Oct 2014	Anyone has the BLM700 datasheet?

10th April 2017, 09:42 PM	#28
emocabras diyAudio Member Join Date: Apr 2017	Hello I write from Italy, you very good great job reverse engineering. probe power supply be your creation or integrated probe? I can feed with different dual power supply 9v battery 500mah resistors marked point have tolerance 1%? What power Watts have resistances this circuit? You can publish original probe picture layout component

25th July 2017, 07:34 PM	#29
Coyote973 diyAudio Member Join Date: Jul 2017	@underwurlde : Great post! Perhaps adding a photo of other PCB side and how compensating capacitor are arranged (under resistor divider) would make even more clearer (if your device is still apart). I took a look on schematics SMD type, but I think that R40 is somehow positioned in wrong way. I have searched many current mirrors, Wilson, Widlar,...any current mirror that exists, and haven't found any such mirror that has a resistor in that place. The listed components are quite old and difficult to find. The U441 is now produced by Linear Systems. I wish I could understand the principles of the weird pair jfet + bjt.