Author Topic: Picotest Injector Teardowns  (Read 2017 times)

0 Members and 1 Guest are viewing this topic.

Offline 16bitanalogue

  • Contributor
  • Posts: 32
  • Country: us
Picotest Injector Teardowns
« on: April 10, 2020, 12:05:00 am »
Hello All,

I am not sure if this is the best place to start a discussion about PicoTest Line Injectors. They are useful tools, but tend to be on the expensive side. I wanted to upload what I have to be archived, and for those who wish to design their own or at least are interested in such topics. I hope this helps someone, somewhere.

Picotest J2120A Line Injector
Price: $525
BOM:

(4) Capacitors
  • C1||C2 = 35.7uF
  • C3||C4 = 1.98uF
(1) Resistor
  • 10k
(1) nMOS
J2120A front and rear pics attached.

Picotest J2130A DC Bias Injector
Price: $525
BOM:

(24) Capacitors
  • Parallel, Series network = 27uF
(1) Resistor
  • 10k
I do believe the equivalent network of the 24 caps is 27uF, I may wish to double check when I get a chance.

J2130A front and rear pics attached.

Ridley Injector Isolator Transformer
No specifications really. The manufacturer looks to be Avel Lingberg.
Model CA8518.

I hope this comes out clean, first time poster. Hell of a time with the pics.

*EDIT*
Added front picture of the J2120A.
« Last Edit: April 10, 2020, 07:38:51 pm by 16bitanalogue »
 
The following users thanked this post: Jay_Diddy_B, thm_w, Neomys Sapiens, Sighound36

Online Sighound36

  • Regular Contributor
  • *
  • Posts: 197
  • Country: gb
Re: Picotest Injector Teardowns
« Reply #1 on: April 10, 2020, 12:44:44 pm »
Hello 16Bitanalogue

This was going to be a couple of my next purchases much appreciated.

Seeking quality measurement equipment at realistic cost with proper service backup. If you pay peanuts you employ monkeys.
 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #2 on: April 10, 2020, 12:55:42 pm »
16bitanalogue,

Thank you for the teardown pictures and welcome to the group.

Hello All,

I am not sure if this is the best place to start a discussion about PicoTest Line Injectors. They are useful tools, but tend to be on the expensive side. I wanted to upload what I have to be archived, and for those who wish to design their own or at least are interested in such topics. I hope this helps someone, somewhere.

Picotest J2120A Line Injector
Price: $525
BOM:

(4) Capacitors
  • C1||C2 = 35.7uF
  • C3||C4 = 1.98uF
(1) Resistor
  • 10k
(1) nMOS
J2120A front and rear pics attached.

Snip ...

I hope this comes out clean, first time poster. Hell of a time with the pics.

You seem to be missing the J2120A front picture, showing the AOT2618 MOSFET.

Do you have the J2111A Current Injector in your collection? I would like to see teardown pictures.

Thanks!!

Regards,

Jay_Diddy_B
 

Online fcb

  • Super Contributor
  • ***
  • Posts: 1599
  • Country: gb
  • Test instrument designer/maker G1YWC.
    • Electron Plus
Re: Picotest Injector Teardowns
« Reply #3 on: April 10, 2020, 03:08:34 pm »
Great first post.

The Ridley Injector unit (in blue) is still PatPending (and has been since at least 2010 - no sign of an actual granted patent), looks like it might have a second transformer (3E27 - which is MnZn core material) to handle the HF.

Whilst none of these boxes look like good-value, the BOM cost on the Ridley Injector ($600) unit is much higher than the Picotest ($525+) units.

Ridley videos on YT are pretty interesting.

https://electron.plus Power Analysers, VI Signature Testers, Voltage References.
 

Offline 16bitanalogue

  • Contributor
  • Posts: 32
  • Country: us
Re: Picotest Injector Teardowns
« Reply #4 on: April 10, 2020, 07:46:54 pm »

You seem to be missing the J2120A front picture, showing the AOT2618 MOSFET.

Do you have the J2111A Current Injector in your collection? I would like to see teardown pictures.


I added the front picture of the J2120A to my first post.

I did manage to capture tear down information for the J2112A High Current Injector which is the big brother of the J2111A. I stashed the penciled schematic, BOM, and pictures somewhere. I will have to see where I squirreled them away, but if not I will have to capture them again.

I realize that most of these have a hell of a markup (engineering effort, mechanical design of the box, etc.), but it is certainly worth a DIY solution.
 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #5 on: April 10, 2020, 08:03:46 pm »
Hi group,

Here is the J2120A schematic:




Regards,

Jay_Diddy_B
 

Offline 16bitanalogue

  • Contributor
  • Posts: 32
  • Country: us
Re: Picotest Injector Teardowns
« Reply #6 on: April 10, 2020, 08:10:18 pm »
Picotest J2112A High Current Injector
Price: $1,995
BOM:
I will need to go back and measure the components. I lost that information. It is also difficult to see the part number on the SOIC8 - I want to recall it was an op-amp of some kind.

 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #7 on: April 10, 2020, 08:27:04 pm »
Hi group,

For the J2130A the insertion loss is given as:




Working backwards from this the capacitance is 28.2uF with zero bias.

so 12x 4.7uF in parallel, 2 sets in series.


So we have:




967414-2

Regards,

Jay_Diddy_B
 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #8 on: April 10, 2020, 08:59:36 pm »
Picotest J2112A High Current Injector
Price: $1,995
BOM:
I will need to go back and measure the components. I lost that information. It is also difficult to see the part number on the SOIC8 - I want to recall it was an op-amp of some kind.



This looks like this:




This is basically a current sink that can work with either positive or negative inputs:

Regards,

Jay_Diddy_B
 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #9 on: April 11, 2020, 01:00:39 am »
Hi group,


**** Error - See this Message ****


https://www.eevblog.com/forum/testgear/picotest-injector-teardowns/msg3011600/#msg3011600


*****************************




Here is a working model that comes close to matching the specification that are published by PicoTest.

https://www.picotest.com/images/download/j2112a-spec-sheet-final-hires.pdf

LTspice Model





This is using one of the op-amps available in LTspice.

Simulation Results




I have attached the LTspice model.

Regards,
Jay_Diddy_B

« Last Edit: April 12, 2020, 11:01:46 am by Jay_Diddy_B »
 
The following users thanked this post: thm_w, exe, Neomys Sapiens

Offline 16bitanalogue

  • Contributor
  • Posts: 32
  • Country: us
Re: Picotest Injector Teardowns
« Reply #10 on: April 11, 2020, 04:41:40 pm »
I believe I can get a hold of a few more Picotest injectors.
I am hoping there is a J2110A floating around and the common mode transformer J2102B.

I'll try to keep this updated as they come.
 

Online Sighound36

  • Regular Contributor
  • *
  • Posts: 197
  • Country: gb
Re: Picotest Injector Teardowns
« Reply #11 on: April 11, 2020, 04:50:03 pm »
Thanks for all your efforts chaps first class.

Howabout a group design and build?
Seeking quality measurement equipment at realistic cost with proper service backup. If you pay peanuts you employ monkeys.
 

Online 2N3055

  • Super Contributor
  • ***
  • Posts: 2453
  • Country: hr
Re: Picotest Injector Teardowns
« Reply #12 on: April 11, 2020, 05:55:58 pm »
Fantastic topic!! Great work here!!
 

Offline Ribster

  • Regular Contributor
  • *
  • Posts: 220
  • Country: be
  • Electronics prototyper. Design. Prototype. Consult
    • Ash Labs
Re: Picotest Injector Teardowns
« Reply #13 on: April 11, 2020, 07:27:58 pm »
I can design and assemble some boards if you guys are interested..
www.ashlabs.be
Design of hardware, software with stm32 and prototyping.
 

Online Sighound36

  • Regular Contributor
  • *
  • Posts: 197
  • Country: gb
Re: Picotest Injector Teardowns
« Reply #14 on: April 11, 2020, 10:37:23 pm »
More than happy with that thank you
Seeking quality measurement equipment at realistic cost with proper service backup. If you pay peanuts you employ monkeys.
 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #15 on: April 11, 2020, 11:13:02 pm »
Hi group,

Just playing around in KiCAD:



This software is new to me. I normally use something else.

100mm x 100mm board, no case.

Which injectors are the most useful?

Regards,
Jay_Diddy_B
 

Online Sighound36

  • Regular Contributor
  • *
  • Posts: 197
  • Country: gb
Re: Picotest Injector Teardowns
« Reply #16 on: April 12, 2020, 05:22:15 am »
Hi Jay_Diddy_B

Thank you for your efforts personally I would interested in all of them however the Picotest J2120A Line Injector would be a great place to start
Seeking quality measurement equipment at realistic cost with proper service backup. If you pay peanuts you employ monkeys.
 

Offline _Wim_

  • Frequent Contributor
  • **
  • Posts: 805
  • Country: be
Re: Picotest Injector Teardowns
« Reply #17 on: April 12, 2020, 05:47:55 am »
I can design and assemble some boards if you guys are interested..

I am also interested in these!  :-+
 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #18 on: April 12, 2020, 10:58:48 am »
Picotest J2112A High Current Injector
Price: $1,995
BOM:
I will need to go back and measure the components. I lost that information. It is also difficult to see the part number on the SOIC8 - I want to recall it was an op-amp of some kind.



The pictures that were included are actually the J2111A

I was having difficulty getting the component values, that I can read in the photograph, in the model agree with the datasheet performance.



This are the specifications:



LTspice model J2111A





And the modelling results:



I have attached the LTspice model.

Regards,
Jay_Diddy_B
* J2111A concept model.asc (5.46 kB - downloaded 5 times.)
 
The following users thanked this post: 16bitanalogue

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #19 on: April 12, 2020, 04:30:16 pm »
Hi Jay_Diddy_B

Thank you for your efforts personally I would interested in all of them however the Picotest J2120A Line Injector would be a great place to start

Hi,

I am a few hours into using KiCAD. This what I have come up with for the 2120A:



I am showing the IRF540, but the plan is to use the AOT2618.

The artwork is single-sided:






The board is 100mm x 100mm

The plan is to use Keystone 575-4 for the connections.

Comments?

Jay_Diddy_B
 

Offline 16bitanalogue

  • Contributor
  • Posts: 32
  • Country: us
Re: Picotest Injector Teardowns
« Reply #20 on: April 12, 2020, 10:14:17 pm »
Picotest J2112A High Current Injector
Price: $1,995
BOM:
I will need to go back and measure the components. I lost that information. It is also difficult to see the part number on the SOIC8 - I want to recall it was an op-amp of some kind.



The pictures that were included are actually the J2111A

I was having difficulty getting the component values, that I can read in the photograph, in the model agree with the datasheet performance.



Oops! I couldn't remember which version since it has been several months. The performance is really close to the datasheet, so I would move forward with what you have. In the future, I can update with actual measured values and track down the op-amp that is being used. It may be moot, but I'll be happy to do it.

According to the User's Manual for the Signal Injectors, the J2111A is bi-directional; i.e., it can only SINK current up to 100mA with positive and negative voltages. Where as the J2112A can SINK up to 1A with positive voltages only.
 

Offline 16bitanalogue

  • Contributor
  • Posts: 32
  • Country: us
Re: Picotest Injector Teardowns
« Reply #21 on: April 12, 2020, 10:36:54 pm »


The board is 100mm x 100mm

The plan is to use Keystone 575-4 for the connections.

Comments?

Jay_Diddy_B

I am personally partial to Keystone 7006 and 7007, but for low cost purposes the 575-4 are good.

2-layer, FR4, 1oz copper top pour.
 

Offline Wolfgang

  • Super Contributor
  • ***
  • Posts: 1357
  • Country: de
  • Its great if it finally works !
    • Electronic Projects for Fun
Re: Picotest Injector Teardowns
« Reply #22 on: April 13, 2020, 12:13:11 am »
Picotest J2112A High Current Injector
Price: $1,995
BOM:
I will need to go back and measure the components. I lost that information. It is also difficult to see the part number on the SOIC8 - I want to recall it was an op-amp of some kind.



The pictures that were included are actually the J2111A

I was having difficulty getting the component values, that I can read in the photograph, in the model agree with the datasheet performance.



Oops! I couldn't remember which version since it has been several months. The performance is really close to the datasheet, so I would move forward with what you have. In the future, I can update with actual measured values and track down the op-amp that is being used. It may be moot, but I'll be happy to do it.

According to the User's Manual for the Signal Injectors, the J2111A is bi-directional; i.e., it can only SINK current up to 100mA with positive and negative voltages. Where as the J2112A can SINK up to 1A with positive voltages only.

When trying to build your own, watch for two pitfalls:

- The part has a dead zone at small voltages where the current drawn is completely incorrrect, even if the sense resistor says its OK.
- Have a look at the transistor datasheets. They will die if you draw max. current (dynamic plus offset) at 40V. If you want to keep
  this spec, you need better transistors and better cooling.

 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #23 on: April 13, 2020, 03:03:06 am »
When trying to build your own, watch for two pitfalls:

- The part has a dead zone at small voltages where the current drawn is completely incorrrect, even if the sense resistor says its OK.
- Have a look at the transistor datasheets. They will die if you draw max. current (dynamic plus offset) at 40V. If you want to keep
  this spec, you need better transistors and better cooling.



Wolfgang,

Thank you for the guidance. The cooling for the transistors is certainly inadequate for 3W of dissipation.


And yes there is a dead band where the devices doesn't work properly.



My interest in building these is to find out what they can do.


Regards,
Jay_Diddy_B
 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2073
  • Country: ca
Re: Picotest Injector Teardowns
« Reply #24 on: April 13, 2020, 03:32:51 am »
Hi,

Further to my last reply, the manual that can be found here:

https://www.picotest.com/support.html

On page 44 it says the maximum input voltage is DC +  AC is 5V

5V x 74mA = 375mW

This is consistent with the transistor selection and mounting method.

Regards,
Jay_Diddy_B

 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf