Recent Posts

1

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

2

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.

3

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.

4

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.

5

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?

6

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.

7

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

« Last post by mag_therm on Today at 04:23:54 pm »

Food grade, you might have standards for this, for example if the thermowell breaks, leaks  etc. I was thinking of suggesting silicon oils but that may be toxic.
On the other hand I was reading recentlty that FDA in USA  does not actually prohibit machinery bits and pieces rats mice cockroaches etc.

They only prohibit that stuff from exceeding a certain ppm. !

8

Projects, Designs, and Technical Stuff / Re: No interrupt from AS6501...

« Last post by dietert1 on Today at 04:22:16 pm »

Someone who wants to develop firmware with difficulties using C. Hm.

Today i found a laser range meter in our supermarket at € 17.90. They claim accuracy of 1.5 mm. At 15 cm/nsec time of flight this means a timing resolution of 10 psec. Having seen a unit price of € 27 for the AS6501 at digikey i thought: Is it possible there is a TDC inside and bought one. But nope. They implemented it with an ARM Cortex (GD32E230F6) and a Si5351A synthesizer. So it isn't single pulse detection but a phase measurement.

Regards, Dieter

9

Test Equipment / Re: Cheap oscilloscope for checking mains power quality? Also logging equipment.

« Last post by Phil1977 on Today at 04:18:44 pm »

For finding EMI misbehaviour I can really recommend such a TinySA spectrum analyzer together with an inductivce probe.

By "scanning" your devices with the inductive probe you - contactless! - find the characterstic emission of e.g. SMPS or LED drivers. If you trace down the power supply line with the inductive probe and clearly see one of the contributors, then chances are high you have found the bad guy.

Big advantage of using an inductive probe (e.g. just a 5uH ferrite inductor soldered to a SMA-cable) is that *usually* the coupling for dangerous signal components (DC or 50Hz) is so bad that nothing happens to you or to the SA - at least as long as you slowly approach your subjects.

Probably you would even get along with the non-official TinySA-Clones for this purpose, but the "real" TinySA is so valuable and the price difference is not that much that I would principly take a real one.

10

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

« Last post by HighVoltage on Today at 04:15:27 pm »

For selling PHV 1000 High Voltage Oscilloscope Probe

100:1 400MHz

Datasheet can be found here: https://www.farnell.com/datasheets/33840.pdf

Ideally shipping within Europe, but also possible abroad.

Price 100Euro

Shipping EU around 10 Euro
Shipping abroad around 15 Euro

Thanks!

That price seems high for a 100:1 probe.
What is the new list price?