Recent Posts

1

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.

2

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.

3

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.

4

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.

5

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.

6

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).

7

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

8

Repair / Agilent 3458A 8.5-Digit Multimeter Repair, Teardown & IC Analysis

« Last post by Hugoneus on Today at 10:50:52 pm »

You can watch the video here: [30 Minutes]
youtu.be/VTocNUyGIWM





** SPOILER **

In this episode Shahriar repairs a faulty Agilent 3458A. These highly desirable multimeters have continued to climb in price in the past few years. The last time The Signal Path has repaired one of these units was back in 2018.

This instrument generates several errors both during power up as well as Auto Cal procedure. The error points to a failure in the OHMS measurement mode. Detailed instrument block diagram and schematics are examined. Measurements also show incorrect DC current sourcing during OHMS measurements and the associated circuits are closely analyzed. The problem is traced to a quad-comparator IC. Replacement corrects all problems during ACAL. The battery backup of the SRAM ICs are also replaced to eliminate non-volatile errors. The IC of the comparator chip is also extracted and examined under the microscope.

The repaired instrument performance is verified by using voltage, current and resistance standards.

9

Projects, Designs, and Technical Stuff / Re: ANITA MK IX Restoration

« Last post by SL901B on Today at 10:41:53 pm »

That's fair! I'll have to cross that bridge when I get there, I get that most components weren't built to last ~60 years haha

10

Buy/Sell/Wanted / Re: SOLD — Learning Art of Electronics course kit

« Last post by YetAnotherTechie on Today at 10:31:37 pm »

Just a few days someone was looking for PCB design files, program code, Microcontroller Code, etc. because he couldn't find them anywhere anymore. Do you have them?

https://www.eevblog.com/forum/buysellwanted/tom-hayes-the-art-of-electronics-hands-on-lab-course-program-and-code-listings/msg5442092/#msg5442092