Recent Posts

1

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 60 cm/nsec time of flight this means a timing resolution of 2.5 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

2

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.

3

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?

4

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

« Last post by djacobow on Today at 04:14:37 pm »

The classic code to convert a string with spaces into an array of null-terminated strings uses strtok.

Something like this:

Code: [Select]

uint8_t console_argumentize(const char *input_string, const char *argv[], uint32_t max_count) {                                                                                                                                                             
    uint8_t argc = 0;                                                                                                                                                                                                                   
    memset(argv, 0, sizeof(char *) * max_count);                                                                                                                                                                                         
    char *saveptr = 0;                                                                                                                                                                                                                   
    char *tok = strtok_r(input_string, " \t", &saveptr);                                                                                                                                                                     
    while (tok != NULL && (argc < max_count)) {                                                                                                                                                                                         
        argv[argc++] = tok;                                                                                                                                                                                                             
        tok = strtok_r(NULL, " \t", &saveptr);                                                                                                                                                                                           
    }                                                                                                                                                                                                                                   
    return argc;                                                                                                                                                                                                                         
}


const char *argv[MAX_ARGS];
uint8_t argc = console_argumentize(input_string, argv, MAX_ARGS);

Then, using the struct that nctnico provided, you implement some sort of find command that returns a pointer to the instance of the struct that matches argv[0] (assuming argc is not zero and there is a match), and from that you use the function pointer therein to call the command function with the argc and argv you just created. Et voila!

A fun thing I've done in my last project is to make a command that will take off the first argument and then redispatch to another command with the rest, thus letting me creating command with arbitrary nesting subcommands using the same framework.

5

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

« Last post by KungFuJosh on Today at 04:14:35 pm »

comical or not, professional or not, sds800x cannot see 400-500MHz even on one channel active, prove me wrong.

🤣🤣🤣 I don't need to. The FACT of REALITY is that if you're trying to measure outside of the scopes designed bandwidth, then the results simply won't be accepted by any professional. The results shapirus showed of his DHO800 measuring 500MHz were TERRIBLE. If you think that's something to be proud about, I don't know what to tell you.

Do you need to measure a 500MHz signal? Your scope better be CERTIFIED to do so, or you could be subject to legal action when the product you're trying to sell doesn't meet specs, or the device you certified as functional isn't. Standards and reality matter, unless you're talking about a toy.

Are you looking for a toy or a tool?

Your scope will not be "certified" whatever that means when out of cal either, and I bet most, if not all of your equipment is not calibrated regularly.
Certainly mine isn't, and I intend that to stay that way.

You're right about me personally not needing cal certs (though most of my gear is still within cal, and yes, I will send stuff to be calibrated when I deem it needed).

I couldn't care less about 500MHz signals right now, which doesn't mean being able to visualize that signal is completely useless for everybody. Very few people buy either of the scopes discussed in this thread for certification and measurements in which legal liability is involved, and nobody without periodic calibration.

I do sometimes care, and I have a 500MHz scope, so that's pretty easy to visualize ACCURATELY. 😉 Look at shapirus' 500MHz example above. That's absolutely not an accurate visualization of the waveform. If you want to see an accurate visualization of the waveform, see my video that follows the sweep on a 500MHz scope. Pretending they're the same thing doesn't make it so.

Let's keep the discussion where it belongs. I do agree that the SDS800X-HD is a better oscilloscope overall. I can also see why, for basic use, the DHO800 can be more than enough and in that case in particular it might be a better purchase due to some usability and convenience advantages.

Keeping the discussion where it belongs means actually discussing the limits and proper use of both scopes. Yes, that means the reality of what the scopes are capable of. As I said in my summary, accurately, they both have their pros and cons. As you said, the SDS is a better scope overall. I agree. I'm not arguing that the DHO isn't a good scope for what it is. If the SDS didn't exist, and somebody needed a 12-bit scope under $500, I'd tell them to get the DHO, despite me hating Rigol in general. But the fact is, if you don't need HDMI out, there's a better scope available for the same price. 🤷

6

Beginners / Re: Any off-the-shelf clock using DS3231?

« Last post by floobydust on Today at 04:13:04 pm »

DS3231 does cost an arm and leg USD $12 ea. so there are clones 1/10 the price at large. Some are good.
I have a few Aliexpress clock kits, one is very accurate and another (plexie) runs fast, like a DS1307 not so accurate. I haven't tried replacing the RTC with a reputable part, or it could be crappy firmware.

7

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

« Last post by gf on Today at 04:13:03 pm »

No, it does not have to be periodic. "Perfect reconstruction" only requires that the original signal sampled by the ADC sampled was bandwidth-limited.

The signal in this image is bandwidth limited (5Hz signal, 11Hz sample rate) but sin(x)/x won't reconstruct it unless the filter is infinitely wide and the signal is periodic (which can't happen in practice).

For a practical reconstruction you do not need the infinte sequence. However, you must acquire additional samples, in front of the time window you want to reconstruct, and after the time window. For the reconstruction of 5Hz @11Sa/s with 60dB out-of-band attenuation, about 50 extra samples are sufficient (or IOW, a filter with a length of about 50 sampling intervals).

8

Metrology / Re: Remote controlled DMM DCV INL tester based on voltage divider idea

« Last post by Kleinstein on Today at 04:11:12 pm »

The idea of doing the zero readings also with 2 different readings is to also include a possible offset error (thermal EMF) from the switches. With a careful layout this offset may be small. So only the zero reading at the center would not include the offset from the switches.  For the test one +-10 or +-5 V range this sytem can be OK.

It would be mainly for the low voltage test that a slightly different switch configuration would have been better. This could still be the SPDT switches, just in a different configuration, so that the first switches are used to select the voltages for the test and the 2nd set of switches are used for the 4 steps in a sequence.

9

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

« Last post by OneGeekGuy on Today at 04:08:59 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!

10

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

« Last post by mawyatt on Today at 04:07:46 pm »

That being said, I just got my SDS800X-HD. I'm thinking of buying a DHO800 just to compare them thoroughly, but it's a bit of an expensive thought.

Go for it, we can compare notes

Best,