Recent Posts

1

Projects, Designs, and Technical Stuff / Re: DIY-SMU Project

« Last post by SebastianH on Today at 09:37:26 pm »

Most OPA140/145 in his design either are configured as buffers or do have a capacitor from out to in-. All exceptions that I have found:
1. the integrator/compensator does has an R in series with the capacitor
2. the reference inverter/buffer (there the OPA140/145 might not be the best choice anyway)
3. current sensing (schematics R3, U21.1)
4. voltage sensing (schematics R3, U19.1)

Imho only 3. and 4. are of concern here:
3. In this thread we discussed a different approach using a three-opamp instrumentation amplifier, eliminating the 100k issue. It has been a while - I don't know whether I did a simulation to analyze stability "in circuit". Certainly did a simulation for the instrument amplifier itself (result 2x 10pF .. 22pF for my particular circuit).
4. Might be worth adding footprints for two capacitors (likely something like 2x 10pF .. 22pF as well).

2

Other Equipment & Products / Re: T12 STM32 V2.1S Soldering Station Controller - schematic etc.

« Last post by DavidAlfa on Today at 09:33:08 pm »

Always post pictures,or no help!
Search "245" here: https://www.eevblog.com/forum/reviews/stm32-oled-digital-soldering-station-for-t12-handle/

3

Beginners / Re: What function generator, that does a bit more than just a simple signal

« Last post by radiolistener on Today at 09:32:01 pm »

It also supports arbitrary waveforms uploaded from a computer. Never tried that, either, so I'm not sure what software is available and if it's any good.

It is possible that it is compatible with PSG9080. If so, then can be used my tool: https://github.com/qrp73/PSG9080_ARB

4

Projects, Designs, and Technical Stuff / Re: Vacuum Fluorescent Display Driver

« Last post by floobydust on Today at 09:31:56 pm »

Look if the VFD filament wires are glowing dim orange. Recheck your soldering, especially to the (filament) pins which are on the far outside ends of the tube.
I'm not clear what it is doing now.

5

Buy/Sell/Wanted / Re: FS: Siglent SDS1104X-E

« Last post by mmora on Today at 09:25:05 pm »

It is SOLD now (not in this forum, however, but via the local app).

6

Other Equipment & Products / Re: T12 STM32 V2.1S Soldering Station Controller - schematic etc.

« Last post by geonicz on Today at 09:23:15 pm »

Hi everyone!
Hope someone can help me with my trouble. I've just bought one more pcb from China, cause they're like leftovers from the past and cost much less than other versions without docs, with strange controllers onboard and without ability to flash devidAlfa's firmware. So, it was a good looking choice. I had one for long enough and deividAlfa's firmware forced me buy one more. Mostly for c245 and c210 tips. It's called the "2.1S original pcb" sometimes. At least in dreamcat4's project. Here is a photo of this controller. Schematics is also there. I've flashed firmware, connected t12 tip, connected c210 tip. Everything works fine. But the problem is with the c245 tip. I don't know how to connect it to this controller correctly to work with this firmware. Don't know which traces should be cut and which resistors where should be added to support c245 tips. Maybe someone can help with it?

7

General Technical Chat / Re: What did you buy today? Post your latest purchase!

« Last post by w.v.s. on Today at 09:22:18 pm »

Keithley 2400 broken as does not power on.
So hopefully it is a simple fix.
Will arrive next week 

Benno

Will you share some details on the fix here? Would be interested in reading that!

8

Test Equipment / Re: Micsig Current Probe CP2100A/B Tests and Comparing

« Last post by Kean on Today at 09:21:45 pm »

Apologies, waking up an old post...

Can anybody help translate MicSig's specified Accuracy, identical language for CP2100A & B.  It's entitled "DC accuracy" but then uses "Apk" which I assume means "Amperes Peak", which wouldn't be DC.

DC accuracy (typical)     
3%±50mA (10A)                          {I'm guessing this line is DC, on 10A range, but no equivalent for 100A range}

4%±50mA(100A,500mA~40Apk)  {maybe AC accuracy if Amps peak is <40Amps, up to bandwidth limit  .8 or 2Mhz}

15%(100A,40Apk~100Apk)     {maybe AC accuracy if Amps peak is >40Amps, up to BW  .8 or 2Mhz.  saturation of steel core??  so reads lower than reality}     

Your post is a year old, but I thought I'd reply.

The way I read it has nothing to do with AC current, but DC with possible transients.

DC accuracy (typical)     
3%±50mA (10A)                           {DC accuracy on 10A range}

4%±50mA(100A,500mA~40Apk)  {DC accuracy on 100A range, from 500mA to 40A}

15%(100A,40Apk~100Apk)          {DC accuracy on 100A range, from 40A to 100A}

9

Test Equipment / Re: UTG932 testing by multiple instruments with a lot of screenshots

« Last post by electr_peter on Today at 09:16:43 pm »

Useful data on UTG932 in pdf. There is a main thread on UTG932/UTG962 with detailed info in case you missed it.
UTG932 can be easily persuaded to become UTG962. Also, BNC connector replacement is a good idea.

While UTG932E output frequency is limited by 30 MHz, it is possible to get a sinusoidal wave with significantly higher frequency using Arbitrary waveform defined to contain 10 sinus periods. When using such ARB waveform the actual output frequency is 10 times higher than the frequency shown on the UTG932E screen. Unfortunately, in this case frequency-dependent amplitude correction is not applied by UTG932E, so the amplitude shown by 1 second 10MHz to 80 MHz sweep is lower than it would be in non-Arb mode

Interesting way to obtain higher frequency output.

At the turn-on moment the power supply current has short spikes exceeding 6A, then for about 8 ms the current is between 4A and 3.2A
...
Only after that current drops to normal 1A. Such high current glitches explain why it was not possible to power UTG932E by power bank with 2.4A rated output.

Current peaks are from inrush current to input caps of SMPS. It is not that bad, there much worse cases where switches fail in time (weld themselves) due to uncontrolled high inrush current.
Most powerbanks with <2A should work except those with have very quick overcurrent detection. Solution is to add simple soft-start circuit to limit inrush current.

10

Beginners / Re: What function generator, that does a bit more than just a simple signal

« Last post by shapirus on Today at 09:16:00 pm »

I would pay about 80€ like you had. But they are all around 140€... There is not much in it, its 95% air.

But i think one device would be good, as they have 2 channels which i could combine, to have them running synchronously.

My primary use at the moment would not be logic levels.

One of these https://www.aliexpress.com/item/1005005364938931.html ? Not sure what it displays for you in terms of price, for me it's US$85 for the 60 MHz version.

Not the best ergonomics-wise, but it works. Two channels, so you can combine them using some RF power combiner. I've not tried that though.

It also supports arbitrary waveforms uploaded from a computer. Never tried that, either, so I'm not sure what software is available and if it's any good.