Recent Posts

1

PCB/EDA/CAD / Re: Four ground layers stitched together under an Artix-7 FPGA is a bad idea?

« Last post by asmi on Today at 05:52:44 pm »

So now it is
Top
Sig
GND
Sig
PWR
Bottom

Each signal layer is adjacent to GND

It doesn't seem so to me. What about top and bottom layers? What are they referenced to?
Also - referencing high-speed signals to a power rail is an advanced technique which should only be used by experienced designers who understand what are they doing, as there is a very high risk to screw things up.

Is the fan really justified? My implementation report shows room 25.9 *C temperature but it's only 27-29MHz the image part of it

Absolutely. That report is a classic example of GIGO (garbage in - garbage out) - you provide crap input, it generates crap output. Unless you provide it with realistic input switching data, it won't output anything useful at all.
BTW if you need A200T but running only at 29 MHz, I strongly suspect that you can double the frequency and fit everything into A100T.

2

Repair / Re: Agilent 34401A Bubble on PCB ... can it be saved ?

« Last post by Kleinstein on Today at 05:52:24 pm »

A damaged capacitor C210 is possible, e.g. due to PCB stress from the bubble. For a test one could try without or with a different low leakage type, possibly also through hole and a slight larger values like 330 pF.  C0G capacitors should be reasonable low leakage, also for more normal types.

With the flux it is also possible that just re-soldering effects leakage on the PCB. The flux linked should be easy to clean and at least for a first test should even be OK without extra cleaning. Excessive flux that did not got hot may however be a problem and likely needs cleaning.

The AD706 should still be available and the photo shows a SO8 foot-print, not a dip. For the wide / narrow version one often can bridge the gap, though this can make PCB cleaning a bit more tricky.

3

Other Equipment & Products / Re: CFW for KSGER/Quicko STM32 Soldering Stations

« Last post by Chris02 on Today at 05:50:02 pm »

I know this problem very well :-) Step by step I'll countinue and I'm sure I'll also need my time

Sometime ago I read a post from you that is it possible e.g. to run a 12V Iron at 24V by setting PWM. Am I right? Is there any documentation how to do it at the station. I guess you have to halve the duty cycle.

Running C470 @48V/6,6A is working pretty well. Now I want to try to use AT420 (tweezer) with two C245 cartridge @48V. So it will be possible to use one power supply für C470/C245.
The Problem will be two C245 parallel (3,2Ω||3,2Ω=1,6Ω) will result a peak current of 30A. Antiparallel PWM, for every cartdrige, can solve the problem. But I'm not able to adapt your code. Maybe a big cap will solve it too.

Are there any other software parameters I can try to solve this problem?

4

Cooking / Re: Rare "Sunday" dinner time.

« Last post by Bryn on Today at 05:47:24 pm »

So, did you enjoy it nonetheless? Good to eat healthily once in a while...

5

Test Equipment / Re: Fool'n around with DSO & AWG

« Last post by Sensorcat on Today at 05:46:59 pm »

When I discovered this thread, I thought this "Ad-hoc Curve Tracer" is great for me and everyone who does not like to have another box getting dusty while waiting for the next time it is needed. Since I do not have an analog scope, the only disadvantage I see is the not-so-impressive performance of many DSOs, including mine, in XY mode. But it appeared to me that XY mode is not necessary for a curve tracer, because it has a linear function of voltage on one axis, and the usual YT mode has a linear function of time.

So I set up the circuit and my AWG as presented by @mawyatt above and played around with instrument settings on my Rigol MSO5000. For the sake of completeness, the transistor is a BC238A. What I got is shown in image 'curve_tracer_YT'.

Compare this to using XY mode, with and without HighRes activated, images 'curve_tracer_XY_HighRes' and 'curve_tracer_XY_Normal'. HighRes does not perform well (especially in XY mode), a known flaw of the MSO5000, but somewhat reduces the trace width, while producing additional artifacts in XY. I started with YT mode and later did not change channels, so the XY images are not in the commen orientation.

Clearly, YT mode produces a better result, a cleaner image without dots all over the screen. Since it does not depend on the DSOs XY performance, it is expected that using YT mode improves the result on many DSOs. Another advantage of YT mode is that the whole screen area can be used. It would be easy to expand the traces to hide the parts left and right of the actual curve tracer plot, to match the image that XY mode provides. I thought I leave it as it is, because this way it shows what's going on.

The scope settings that required attention are:

• In Display menu, 'Dots' instead of 'Vectors' to reduce line width
• In Display menu, 'Persistance' = 5s, 'Intensity' = 100%, 'ColorGrade' = OFF, 'Waveform Freeze' = ON. These settings make all lines appear similar, regardless of the plotting sequence, and all lines stay on screen if the acquisition is stopped, for instance to take a screenshot.
• In Acquisition menu, 'HighRes' = ON, 'Mem Depth' = 10k

6

Projects, Designs, and Technical Stuff / Re: How to install custom Sigrok Pulseview protocol decoder?

« Last post by AndySymons on Today at 05:45:27 pm »

Yeah 'registration' is not 'installation' and I do have the API spec (https://sigrok.org/wiki/Protocol_decoder_API).

By trial-and-error I found that on MacOS the procedure is

• Find pulseview.app in your Applications folder
• Right click and select 'show package contents'
• Navigate to /Contents/share/libsigrokdecode/decoders/
• Either create your own folder here or copy and existing one then change the name
• Within that folder create or edit the copied files __init__.py and pd.py as described in the HowTo guide (https://sigrok.org/wiki/Protocol_decoder_HOWTO#Files). If you copied an existing protocol to use as a template, you need at least to change its name to a unique one (search for the old name and replace it, preserving the capitalisation).
• (Re)start the Pulseview app
• Now if you press press the decoders button, the resulting list should include your new decoder

     
I Have no idea how to install the PD in any other environment!
 
It is remiss of Sigrok not to include this information in the HOWTO guide.
 
 

7

Beginners / Re: Snubber circuit for MOSFET with inductive load

« Last post by KKK on Today at 05:45:11 pm »

From some simulations done on the first circuit (snubber1) I notice that if you have a low switching frequency, less than 1Khz, if I increase R the peak increases.
The fast recycling diode alone performs much better than the RCD circuit....

8

Repair / Re: screws, bolts and fasteners used on vintage TE

« Last post by mikeselectricstuff on Today at 05:42:25 pm »

imperial allen keys go down to 1/64" increments

9

General Technical Chat / Re: A Little Semiconductor Related History

« Last post by rsjsouza on Today at 05:41:57 pm »

I haven't seen this thread. Subscribed. Hopefully more stories come.

10

Beginners / Re: Lifting and tilting 0402 SMD LEDs by solder paste while soldering

« Last post by ebastler on Today at 05:39:45 pm »

Wait what???
It can do those things when above melting temperature?? I will try in a minute again with 190*C max

I had another "what?!" moment too... On second thought, the temperatures stated in that data sheet appear too low. And suspiciously, they are exactly the same as in the data sheet for the leaded paste. So probably a copy-and-paste error?

https://termopasty.com/wp-content/uploads/2019/07/Profil-karta-tehniczna-Pasta-olowiowa-ang-2-1-new-1.pdf