Recent Posts

1

PCB/EDA/CAD / Re: ltspice model for irs2186 half-bridge driver or similar?

« Last post by julian1 on Today at 11:18:39 pm »

Ignore me. There's an official pspice model,

https://www.infineon.com/cms/en/product/power/gate-driver-ics/irs2186s/#!designsupport

2

FPGA / Re: Lattice has silently removed free iCEcube2 license and now charging $471

« Last post by asmi on Today at 11:15:15 pm »

Yeah all those cheap FPGA boards with their devices suddenly turned into pumpkins. I wonder why such a decision was made, as I can't really see them making any kind of serious money with that, but it's guaranteed to drive away customers and prospects alike...

That said, I always thought that their approach of supporting a whole bunch of different toolchains is kind of wasteful and unsustainable in the long term. It seems much more efficient and cheaper to have a single toolchain which supports all devices.

3

Projects, Designs, and Technical Stuff / Re: Parametric TEM cell design

« Last post by tomud on Today at 11:12:32 pm »

I regret the errors, and apologize for any wasted money and effort spent on replicating my unsuccessful design. Please don't build my TEM cell as proposed above, and use this thread as a study on how NOT to design a TEM cell.

I'll bring my new conversations here: https://www.eevblog.com/forum/projects/tekbox-tem-cell-how-is-it-constructed/

- Alex

There's nothing to regret. Personally, I was interested in the topic and decided to repeat the experiment.

When designing my septum, I modeled it on the TekBox septum (based on photos I found on the Internet - although there are not many of them).
I am currently waiting for the PCB I ordered. Once I get the PCB, I will try to reproduce similar effects (time will tell if I succeed).
In the meantime, I am looking for any scientific studies that will explain the theoretical basis of the solution used by TekBox.

Why do I want to follow the TekBox solution as an example? For a simple reason - looking at this chart, you can see that they achieved very good results.

https://essentialscrap.com/tem_cell/tem_cell_vswr.png

4

PCB/EDA/CAD / ltspice model for irs2186 half-bridge driver or similar?

« Last post by julian1 on Today at 11:09:28 pm »

I found a readme that points to IR-HCdrv.zip, independently developed by analogspiceman.

https://ltwiki.org/files/LTspiceIV/examples/LtSpicePlus/Smps/Ir21xx/IR_readme.txt

But cannot find the zip file. on groups.io or from a google search.

Alternatively a model for a similar high and low-side driver, with independent ctrl channels would probably be fine.

5

Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers

« Last post by RFDx on Today at 11:07:10 pm »

When we want to mosfet to be ON we have to put at least 10V Vgs.

That is correct. I have attached a simplified circuit with a similar optocoupler type driver which should make things clearer. The load (think MMIC amp) is shown here as a simple 50 Ohm resistor. When turned on, the gate-source voltage Vgs in this case is 13.4V (37.4-24V). All voltage probes are referenced to real ground. When the load is turned off all voltages and currents are zero.

6

Test Equipment / Re: Tek 2465 Horizontal Sweep Issue

« Last post by tautech on Today at 11:07:01 pm »

Not sure exactly what changed (reseating U700?) but my sweep is back

With a portion of intensified trace from the dual timebase.

7

General Technical Chat / Re: Model Trains

« Last post by andy3055 on Today at 11:06:14 pm »

If you use a fiberglass pen, you can clean the wheels very well.

8

Repair / Re: Com Express Motherboard - No Image

« Last post by 2X on Today at 11:01:34 pm »

Finally I found the problem... the CPU didn't have supply. There was a Cold Solder Joint on the phase PCB which drives the mosfets at CPU. I resolder the chip and now works fine.

9

Projects, Designs, and Technical Stuff / Re: TekBox TEM cell – how is it constructed ?

« Last post by tomud on Today at 10:58:10 pm »

For those interested, I found a scientific article that explains this problem a bit (attached).

Personally, I'm waiting for the PCB I ordered, so I'm not able to write more at the moment. The PCB is modeled after the TekBox septum - I based it on the photos I found on the Internet (we'll see what the results will be).

10

Test Equipment / Re: Tek 2465 Horizontal Sweep Issue

« Last post by kellymcdonald78 on Today at 10:54:59 pm »

Not sure exactly what changed (reseating U700?) but my sweep is back