Recent Posts

1

Buy/Sell/Wanted / Re: FS (EU/US) PHV 1000 100:1 400MHz High Voltage Oscilloscope Probe

« Last post by OneGeekGuy on Today at 04:37:59 pm »

Hi HighVoltage,

I bought it long time ago and never used it!, not sure if the prices are up-to-date:

https://www.datatec.eu/de/en/pmk-860-622-b00-tastkoepfe-high-voltage

Price can be negotiable, I am not currently on the HV world anymore.

Thanks!

2

General Technical Chat / Re: H5N1 bird flu and how we're risking another global pandemic

« Last post by nctnico on Today at 04:37:37 pm »

https://www.reddit.com/r/H5N1_AvianFlu/comments/1cfdykj/opinion_this_may_be_our_last_chance_to_halt_bird/

Spillovers from animals to humans are common, yet pandemics are rare because they require a chain of unlucky events to happen one after the other. But pandemics are a numbers game, and a widespread animal outbreak like this raises the risks. When dangerous novel pathogens emerge among humans, there is only a small window of time in which to stop them before they spiral out of control. Neither our animal farming practices nor our public health tools seem up to the task.

It's inevitable that factory farming is going to cause another pandemic. If not H5N1, it will be something else later. It adds to the many other health problems related to factory farming as justification to phase it out and replace it with sustainable farming.

It doesn't work that way. You have to keep in mind that humanity is factory farming humans. The only advantage of factory farming humans is that humans can be vaccinated to higher levels as humans don't need to be consumed. Farm animals bread for consumption are a little more sensitive as their meat ends up in our food chain. Either way, infectious disseases will spread and the only way out is through keeping vaccination levels up to high percentages. Over here in the NL people (mostly young kids) die again of disseases which have not been problematic for decades due to stupid people not trusting vaccines due to spread of false information.

History has shown world-wide pandemics occur about once every 100 years so you are safe.

3

Repair / Re: Laser Level Charger PCB ID

« Last post by coromonadalix on Today at 04:32:56 pm »

You could have a battery pack with "memory", meaning  they could show some voltage  but wont charge if everything is okay ...

Sometimes  companies use cheap packs or cell ...  if you can provide some 4volt  on the battery connector and everything powers up,  you'll know they are not good

and yes  with found parts dustsheets, STM32 mcu and the battery charger ic       you should be able to pinpoint where is your problem is / are  if there is, or the battery is not good

some rechargeable batteries do have some protection on one end,  when you unfoil the blue plastic,  some batteries may or could have an small pcb, and this pcb can open if there is a problem, it may act as a fuse / bms  ...

4

Projects, Designs, and Technical Stuff / Re: Linear acceleration of stepper motor

« Last post by Doctorandus_P on Today at 04:32:10 pm »

Just an FYI for Andre, there is a project that might suit called GRBL: https://github.com/grbl/grbl
which runs on an Arduino, it takes GCode commands and controls the stepper motors, it is used quite extensively and would probably suit your application.

GRBL is an old project. It has not been updated for several years. Development of GRBL has moved on to grblHAL. Development of GRBL was forked into many different uC architectures, and lots of forks on github and this made introducing new features difficult. GRBL has also outgrown the classic 8-bitters, and benefits from both more Flash a faster uC (Cortex M3, ESP32, etc, and probably more advanced features (DMA and such). With GrblHAL (= Hardware Abstraction Layer) a lot of forks of GRBL have come together again, and you can compile in extra modules (for example for controlling a frequency inverter over MODBUS).

There is a quite popular article about calculating acceleration / deceleration written by David Austin. It is published on a lot of sites (EDN, EEtimes, etc). It has found it's way into several application notes (Including atmel back then, now microchip), and you find a lot of other references:

https://html.duckduckgo.com/html?q=david+austin+stepper

But overall, I would probably just fork GRBL-HAL, add a self written module to generate some lines of G-code on the uC itself and put that in the right buffer and then be done with it. Some architectures with grblHAL support upto 8 motors.

5

General Technical Chat / Re: Dumpster diving save VFD

« Last post by Miti on Today at 04:30:49 pm »

I see a lot of wires, does this module have a serial port? Some of them have a small 3 pin header on the board for serial. I think it even breaks out to the parallel header

This is 3 lines serial module, but you need to supply 5V, 36V, GND, filament supply.
So what you see there is exactly that, 5 wires going to Arduino and the supplies to the module itself.

Cheers,
Miti

6

Projects, Designs, and Technical Stuff / Re: Build or buy? Multi-level vessel temperature logger

« Last post by voltsandjolts on Today at 04:29:47 pm »

Aside: This ^^ has been done many times!

Yes, it's been done many times.
We use it several km underground and it works well.
But I haven't seen any low budget options, which might be an interesting project for a multi-level vessel temperature logger (which is the thread title btw).

7

Microcontrollers / Re: primitive serial CLI / Console for embedded systems - Ideas for implementation?

« Last post by nctnico on Today at 04:29:44 pm »

And one extra question.
Does it make sense to optimize the CLI for VT100/Putty/miniterm type of communication (each character transmits immediately after the keypress) or for terminals that "wait for enter" (e.g. Termite) and send the whole line?

In my implementation I echo the incoming characters and support the use backspace for use with hyperterminal/putty/mincom/etc. Thats it. I find the single like terminals (like Cutecom) highly annoying to use because you need to switch between input fields all the time.

8

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by shapirus on Today at 04:25:49 pm »

The results shapirus showed of his DHO800 measuring 500MHz were TERRIBLE.

No, they were actually unexpectedly good. Mind you, I was capturing a signal way beyond the scope's claimed specs.

The point of showing that capture was only to demonstrate that the digital backend was capable of visualizing signals of that high a frequency, and if one would wish to modify the input low-pass filter on one of the channels to make it a special high-frequency input, then it would not be pointless at all.

I have no reason to expect that the SDS800X HD will not show an equally terrible, or good (if not better), result in the same test scenario. Might even be much better (because of a higher sampling rate), but it would equally require a modification of the input filter to make it practically useful.

Your comments on the number of channels and effective bandwidth sound somewhat apocalyptic. No, it's nowhere near that in reality.

It's true that the front page specs are somewhat misleading. If we consider DHO924, then the claimed bandwidth (250 MHz) is only usable in single channel mode, and just barely hits it in dual channel. Does it render the scope useless? Of course it doesn't. Is Rigol DHO800/900 worse than the respective Siglent for multi-channel high-frequency measurements (simultaneously)? Yes, apparently so. Is it worse in every other aspect? No it's not. Siglent also has a significant number of things that can be more or less annoying.

It's good to know the instrument's limitations (and bugs/weird design choices), and that's where the forum comes to help, as we can test things to see what practical implications their limitations may create.

9

Test Equipment / Re: Siglent SDS2000X Plus Hack

« Last post by blurpy on Today at 04:24:42 pm »

I was also curious about the .ads files (that's another interesting thread), and it looks like they're still using some of the same obfuscation techniques (reverse file, xor 0xff pattern), but it does look like it's not exactly the same as it used to be.

Seems to work exactly the same to me. What change did you encounter with the obfuscation?

10

Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude

« Last post by TimFox on Today at 04:24:01 pm »

But I do know today that I am iterating options how to generate sine wave - as clarified in the initial message including an example circuit.

Quadrature oscillator might be "the fresh idea I was looking for". Just that none of the first examples I tried to simulate on LTspice didn't work. Like this one:
Probably a simulation related issue - I need to analyze it further...

Whilst that circuit has two waveform at 90', it also has 3 RC elements, so it is less suited to a knob controlled oscillator.
When simulating such oscillators, you need to adjust the idealized gain, to account for real opamp effects.
You then find a trade off between oscillator startup time and clipping of one node when stable.

Lab instruments (such as the Krohn-Hites) using quadrature oscillators require precision resistors on decade switches and precision capacitors on the range switch.
The OP's requirement is for a fixed, non-critical frequency, so matching resistors and capacitors using reasonable meters can give an acceptable solution for non-tunable frequency.