5uH LISN for Spectrum Analyzer EMC/EMI work

[HallWu]

Hi Bart and the group,

Did you have any issue with the cored inductors rather than air?
was your line lisn 110 or 230V?
Regards
Bart

The inductance of the inductors is not super critical. Ideally the LISN should look like 50 Ohms to the input. The impedance of the 50 uH is 314j Ohms at 1 MHz.

Here are some pictures of my LISN








I did a measurement of the input impedance using an HP 3577A Network analyzer with a s-parameter test set. One of the challenges connecting the power connector to a coax cable. (Where is my precision N to power connector adapter?)



The return loss is 23 dB at 30 MHz



This is a picture of insertion loss. Ideally it would -10db and flat. It is hard to normalize this measurement because the power connectors are not very good at 50 MHz 



Since this is used for pre-compliance testing, you compare the results against the results from the lab.

Regards,

Jay_Diddy_B

Hi Thanks for all the information.

I am trying to design a 5uH LISN based on your works which suitable for DC 200V situation. What should i notice when i choice the compoents and design the pcb ? I have browsed many scheme in the internet which based on your work, such as Wurth and LINEAR, the maximum input voltage is 60V. What should i do to improve the input voltage to 200V. Look forward to your reply.

Best Regard,
Hall.

[TimNJ]

Hi Thanks for all the information.

I am trying to design a 5uH LISN based on your works which suitable for DC 200V situation. What should i notice when i choice the compoents and design the pcb ? I have browsed many scheme in the internet which based on your work, such as Wurth and LINEAR, the maximum input voltage is 60V. What should i do to improve the input voltage to 200V. Look forward to your reply.

Best Regard,
Hall.

The voltage rating is mainly related to:

1. Voltage rating capacitors across AC or DC power rail
2. PCB spacing

For capacitors across the rail, instead of 100V rating, suggest >500V, especially if you are connecting directly to mains. You can consider using X2 or Y2 safety types, or a 630 - 1000V rated normal film type.

For PCB spacing, spacing between line and neutral and between line/neutral to earth should be increased. A rather conservative value is around 7-8mm.

You should also consider adding a bleeder resistor (with proper power rating) across the input capacitors because 200V is quite a bit more painful/dangerous than 60V.  If using with mains, add some fuses.

[HallWu]

Hi Thanks for all the information.

I am trying to design a 5uH LISN based on your works which suitable for DC 200V situation. What should i notice when i choice the compoents and design the pcb ? I have browsed many scheme in the internet which based on your work, such as Wurth and LINEAR, the maximum input voltage is 60V. What should i do to improve the input voltage to 200V. Look forward to your reply.

Best Regard,
Hall.

The voltage rating is mainly related to:

1. Voltage rating capacitors across AC or DC power rail
2. PCB spacing

For capacitors across the rail, instead of 100V rating, suggest >500V, especially if you are connecting directly to mains. You can consider using X2 or Y2 safety types, or a 630 - 1000V rated normal film type.

For PCB spacing, spacing between line and neutral and between line/neutral to earth should be increased. A rather conservative value is around 7-8mm.

You should also consider adding a bleeder resistor (with proper power rating) across the input capacitors because 200V is quite a bit more painful/dangerous than 60V.  If using with mains, add some fuses.

Hello TimNJ,

Thanks for your advice, that helps a lots. I have another questions as follows:

1. Could I use the inductance 744314110 when the Maximum DUT Current no more than 10A, no matter how high the input voltage is?
2. Where should I add the bleeder resistor? Parallel with the input capacitors such as C4 and C5 in the picture? What is the recommended resistance value of the bleeder resistor?
3. Whether the withstand voltage value of the components in the 10dB attenuator needs to be adjusted according to the change of the input voltage?

Look forward to hear from you.
Best Regard,
Hall

[TimNJ]

Hi Thanks for all the information.

I am trying to design a 5uH LISN based on your works which suitable for DC 200V situation. What should i notice when i choice the compoents and design the pcb ? I have browsed many scheme in the internet which based on your work, such as Wurth and LINEAR, the maximum input voltage is 60V. What should i do to improve the input voltage to 200V. Look forward to your reply.

Best Regard,
Hall.

The voltage rating is mainly related to:

1. Voltage rating capacitors across AC or DC power rail
2. PCB spacing

For capacitors across the rail, instead of 100V rating, suggest >500V, especially if you are connecting directly to mains. You can consider using X2 or Y2 safety types, or a 630 - 1000V rated normal film type.

For PCB spacing, spacing between line and neutral and between line/neutral to earth should be increased. A rather conservative value is around 7-8mm.

You should also consider adding a bleeder resistor (with proper power rating) across the input capacitors because 200V is quite a bit more painful/dangerous than 60V.  If using with mains, add some fuses.

Hello TimNJ,

Thanks for your advice, that helps a lots. I have another questions as follows:

1. Could I use the inductance 744314110 when the Maximum DUT Current no more than 10A, no matter how high the input voltage is?
2. Where should I add the bleeder resistor? Parallel with the input capacitors such as C4 and C5 in the picture? What is the recommended resistance value of the bleeder resistor?
3. Whether the withstand voltage value of the components in the 10dB attenuator needs to be adjusted according to the change of the input voltage?

Look forward to hear from you.
Best Regard,
Hall

The inductors will not have much voltage across them. The voltage across the inductors is only caused by the DC resistance of the wire and some voltage related to V = L * di/dt. Generally, voltage breakdown (turn-to-turn) of inductors is unlikely, unless you are working with high voltages (>1KV), with something like a CRT flyback transformer. Don't worry about these inductors @ 200V.

Do you plan to use this LISN with AC? If yes, then do not use a polarized (electrolytic) capacitor for C5. Use a film type (polypropylene) instead. (The large blue/green capacitors in JayDiddyB's post above.) Depending on the standard, usually this capacitor must be 1-10uF, or thereabouts. This capacitors (or group of capacitors) should be rated 630V - 1000V, or use a X2/Y2 class capacitor(s).

The -10dB attenuator does not need to be modified, but C3/C6's voltage rating needs to be increased to work with mains. In the above photo, you can see 100nF film capacitor (probably rated 630V or 1000V). Most of the voltage is  across C3/36, and only a small voltage is developed across R5/R13.

Add the bleeder resistors across C4/C5, yes. You can set the bleeder resistor to any value you want, depending on how quickly you want to discharge the capacitors C4 and C5. http://www.learningaboutelectronics.com/Articles/Capacitor-discharge-calculator.php. Lower value of discharge resistor means faster discharge, but the power dissipation during normal operation will be higher. Suggest a power rating at least 2x the calculated power dissipation @ 200V/240V.

[HallWu]

Hi Thanks for all the information.

I am trying to design a 5uH LISN based on your works which suitable for DC 200V situation. What should i notice when i choice the compoents and design the pcb ? I have browsed many scheme in the internet which based on your work, such as Wurth and LINEAR, the maximum input voltage is 60V. What should i do to improve the input voltage to 200V. Look forward to your reply.

Best Regard,
Hall.

The voltage rating is mainly related to:

1. Voltage rating capacitors across AC or DC power rail
2. PCB spacing

For capacitors across the rail, instead of 100V rating, suggest >500V, especially if you are connecting directly to mains. You can consider using X2 or Y2 safety types, or a 630 - 1000V rated normal film type.

For PCB spacing, spacing between line and neutral and between line/neutral to earth should be increased. A rather conservative value is around 7-8mm.

You should also consider adding a bleeder resistor (with proper power rating) across the input capacitors because 200V is quite a bit more painful/dangerous than 60V.  If using with mains, add some fuses.

Hello TimNJ,

Thanks for your advice, that helps a lots. I have another questions as follows:

1. Could I use the inductance 744314110 when the Maximum DUT Current no more than 10A, no matter how high the input voltage is?
2. Where should I add the bleeder resistor? Parallel with the input capacitors such as C4 and C5 in the picture? What is the recommended resistance value of the bleeder resistor?
3. Whether the withstand voltage value of the components in the 10dB attenuator needs to be adjusted according to the change of the input voltage?

Look forward to hear from you.
Best Regard,
Hall

The inductors will not have much voltage across them. The voltage across the inductors is only caused by the DC resistance of the wire and some voltage related to V = L * di/dt. Generally, voltage breakdown (turn-to-turn) of inductors is unlikely, unless you are working with high voltages (>1KV), with something like a CRT flyback transformer. Don't worry about these inductors @ 200V.

Do you plan to use this LISN with AC? If yes, then do not use a polarized (electrolytic) capacitor for C5. Use a film type (polypropylene) instead. (The large blue/green capacitors in JayDiddyB's post above.) Depending on the standard, usually this capacitor must be 1-10uF, or thereabouts. This capacitors (or group of capacitors) should be rated 630V - 1000V, or use a X2/Y2 class capacitor(s).

The -10dB attenuator does not need to be modified, but C3/C6's voltage rating needs to be increased to work with mains. In the above photo, you can see 100nF film capacitor (probably rated 630V or 1000V). Most of the voltage is  across C3/36, and only a small voltage is developed across R5/R13.

Add the bleeder resistors across C4/C5, yes. You can set the bleeder resistor to any value you want, depending on how quickly you want to discharge the capacitors C4 and C5. http://www.learningaboutelectronics.com/Articles/Capacitor-discharge-calculator.php. Lower value of discharge resistor means faster discharge, but the power dissipation during normal operation will be higher. Suggest a power rating at least 2x the calculated power dissipation @ 200V/240V.

Hello TimNJ,

Thanks a lot for your excellent advice . I will start my design based on your advice. Looking forward to a good result.

Best Regard,
Hall

[uski]

Hi,

Hello All,

Thanks to Jay_Diddy_B & Noy.

I have made these modifications to the layout:

1) Corrected the trace widths for 50 ohm impedance.
2) The spacing between +/GND and -/GND banana jacks has been changed to standard value of 0.75" (19.06 mm).
3) "JLCJLCJLCJLC" moved to bottom side of the PCB.

Regards,
Mathews

I was considering building this.
However, it seems like the Gerber files are from the previous, unmodified version.

Can you please upload the modified gerber files?

[EDIT] I was able to export the Gerber files from Kicad. No guarantees. See attached file. Thanks!

Thanks!

[Jay_Diddy_B]

Hi,

I viewed the gerber files provided in the previous message. This is what I found:







The banana plugs have 19.05mm 3/4 inch spacing.

They look reasonable.

Jay_Diddy_B

[uski]

Thanks for looking. I am ordered a few PCBs from JLCPCB, and a whole bunch of parts from DigiKey. I am going to build one.

What abou the 50uH version? I am confused, what is it used for? I thought the 50uH LISN were line voltage LISN, and this 60V LISN can't do it. Right? What am I missing? What is the purpose of having a 50uH version of this small LISN?

I do have 2 LISN of the "original" design by Jay_Diddy_B (thank you!!!) that I used successfully in the past (thank you!!! saved my ass during precompliance testing), but I like the "all in one" version.

[T3sl4co1l]

You probably wouldn't want to apply line voltage to that, given the clearances, yeah.  Inductors that size won't have great saturation current, either.  But you could still use it for 24VAC things I suppose, if that was ever a need?...

Probably not a lot of things running at low voltage, that would still be useful to know their response at lower frequencies (10s instead of 100s kHz cutoff), but regardless of applicable standards, that's simply the effect, so, whatever you make of it.

Oh also, for posterity, I should link this high current LISN I made: https://www.eevblog.com/forum/projects/high-current-lisn/msg4576645/#msg4576645 No PCB designs, it's just bits soldered/glued together anyway, obvious enough.  Capacitors rated 400V so it could potentially be used for quite some power.

Tim

[Smokey]

...
Will upload the design files for CM/DM seperator in the other thread..

Did you ever end up making that CM/DM separator?  How did it work?

Note:  Probably this thread: https://www.eevblog.com/forum/projects/diy-dm-cm-seperator-for-emc-lisn-mate

[Smokey]

I'm looking at making one of these dual 5uH LISNs...

I read through the thread and I didn't see anyone with any numbers on how much it actually costs to make one of these... so..

Based on the files in this post by matbob: https://www.eevblog.com/forum/projects/5uh-lisn-for-spectrum-analyzer-emcemi-work/msg3789893/#msg3789893

10 PCBs from PCBWay, with shipping = $36USD
BOM at Digikey (1 set of parts, no shipping) = $75USD

So, as of right now, about $125USD to make one dual 5uH LISN.

[Smokey]

Thanks for looking. I am ordered a few PCBs from JLCPCB, and a whole bunch of parts from DigiKey. I am going to build one.

What abou the 50uH version? I am confused, what is it used for? I thought the 50uH LISN were line voltage LISN, and this 60V LISN can't do it. Right? What am I missing? What is the purpose of having a 50uH version of this small LISN?

I do have 2 LISN of the "original" design by Jay_Diddy_B (thank you!!!) that I used successfully in the past (thank you!!! saved my ass during precompliance testing), but I like the "all in one" version.

There is another whole thread about 50uH LISN:
https://www.eevblog.com/forum/rf-microwave/50uh-and-250uh-inductor-design-for-lisn/

[ironcurtain]

I found this: https://github.com/westonb/leery-lisn/tree/master

Not sure if it has been linked before, but it does mention this thread. The design seems quite sensible. I had some difficulty digging out the part numbers, unfortunately, but most were visible in the photos.

Uses a bunch of ECQ-UAAF275K which are sadly EoL :-(