Recent Posts

1

Computers / Re: Format a 256GB pendrive with FAT32 using a windows 10 pc

« Last post by langwadt on Today at 05:40:59 pm »

I seem to recall that you can format large FAT32 volumes in Windows using its bundled command line tools (format or something like that). The 32GB limitation is only imposed by the GUI.

afaiu you can do it on the commandline but it is very slow, so it's better to get a thirdparty tool

2

Projects, Designs, and Technical Stuff / Drive 36" pcb traces

« Last post by davethomaspilot on Today at 05:40:23 pm »

I'm designing a light curtain that has 12 IR diodes spaced 3.5" apart.  The length of a single trace for all 12 diodes would be about 40".

The parts I want to use for the receiver require a clock input at approximately 5 Mhz (for my application conditions).

I can make the pcb trace width whatever is optimal.  I'm thinking that would be minimum trace width to keep the capacitance low (but I'm familiar with transmission line design for impedance matching).

There are actually four pcbs, each 10.5"  long with three receivers each.  They connect with right angle,  .100" headers/receptacles.

Clk input capacitance for the receiver chips isn't specified, so I'm assuming 10 pf (max) each.

I'm thinking I'll need at least a separate buffer for each 10.5" card, but may more. 

Hopefully, I could use something low cost like an AHCT device for the buffer.

I'm looking for suggestions on how to drive the trace, how many buffers (if any) needed, or any other advice.

Thanks!
 

3

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by PlainName on Today at 05:35:35 pm »

I initially thought of it as a Facebook for work related stuff. So you could make use of the contacts you have at work and not have them see the crazy stuff you get up to at the weekend.

I avoid it mostly as it wants to be a job advertising website and is infested with agencies trying to sell me a job that I left years ago.

Some of the headhunters are completely useless. I had one that cold called me on my work phone to try to poach me. I was sitting 1.5m from my boss.

I've had a headhunter call me at my workplace too, company phone! - which I thought was pretty dumb.

I can beat that.  I've had one email me on my work email about a new job offer. Come on, man... How stupid can you be...

I must be living in a backwater. Why is contacting you at work - by a headhunter - dumb? How else are they supposed to contact you@your_work since I'm pretty sure you wouldn't splash your private phone number and email all over the interwebs (and if you did, probably not link them to your CV). Worst case, surely, is they get blocked by your company but there's a chance you may follow up, which is all they're after in the end.

4

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

« Last post by tggzzz on Today at 05:31:32 pm »

I have never understood replies like tggzzz. Nothing valuable to say, full of negative load. Waiting for missing parameters. Oh well...

Suggested reply for the next time:
"It depends on the frequency response, output voltage and drive capability. Please give us more detailed specifications in order to give exact opamp examples. However, in general, I can say that typical opamps used for low-frequency applications, which are the common use cases for wien oscillators, are for example LT1632, LT1013, LT1001".

or.... just ignore the question.

br,
sw guy

Bizarre response. Why spend time and energy avoiding giving the information necessary before people can help you!

Do you actually want to be helped?

5

Beginners / Fast PWM IC

« Last post by elki on Today at 05:26:34 pm »

Is there any IC that could provide a PWM at 100 MHz or so? I would love to use atmega ICs but these go up to 20 MHz, if I am not mistaken. The idea is to use it for a voltage control in sample-and-hold circuit for short input pulses. Thanks!

6

Beginners / Re: Resistor ????

« Last post by Herschel on Today at 05:22:19 pm »

if the second band from the nearest ist band is silver, it would be a 10ohm resistor. So what about the last black band? that depents from where you got that resistor. if its from a cheap chinese powersupply, that makes sense. i have seen a lot of things like this before...
or if the second band is grey, which makes the last(Tolerance band brown making it an 80 ohm resistor with 1% tolerance)

anyway check your resistor here:
https://www.digikey.in/en/resources/conversion-calculators/conversion-calculator-resistor-color-code?_gl=1

7

Test Equipment / Re: EEVBlog 121GW Discussion thread

« Last post by hlj.pycad on Today at 05:08:43 pm »

Hi, I have viewed quite some videos on this DMM and now I am ponderig for it's considerable slow speed against its so many features.
And I also do a little search for other DMM using the same hy3131: Holdpeak HP-770D, UNI-T 171 series, 121GW, AmazonCommercial 90DM860 .. Among thoes name mentioned above, UNI-T 171 series is smoking fast, while the other can place them to "Slow category".

One idea comes up to my mind. Hycon's popular DM0660 is kind of slowly too, but it can double its' speed by changing the 4 Mhz Crystal oscillator to 8Mhz when most of the function keep working¹ . I wonder does this overclocking hack work for HY3131 too. If it is possible, one should change the oscillator of the hy3131 or the MCU, or both of them?

Again, it's amazing how different the speed is comparing UNI-t 171 to 121GW. I would like to have 121GW if I can hack it become faster.



Note:
1. 8Mhz DM0660's voltage, current & temp will work without any modification. Resistor and Capacity will need to tweak the eeprom, easy enough though. Frequency will show result by half, 60Hz will show 30Hz, only function that will "break", but I don't mind for the trade off speed.

8

Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers

« Last post by xvr on Today at 05:02:44 pm »

> For that i need to tune the bias for my single amplifier and to tune sepratly for the pair.

Nothing. Your schematic do not depends of amplifier current (6A for single, 12A for pair), only for amplifier voltage. Voltage the same for both single and pair.
But you need 3 identical channel (including DC/DC and UCC) for control 3 independent subcircuit (1 single + 2 pair)

PS. Consider P channel MOSFETS from my previous post - your current schematic became monstrous 
PPS. Your currently selected MOSFET do not fit to your requirement: only 4A of Id and large Rdsonn - 0.1Ohm. Consider something more powerfull

9

Test Equipment / Re: new killer scope in town - a true game changer from R&S - RTB2002 & RTB2004

« Last post by electronix27 on Today at 05:00:48 pm »

This last thing may be of use to someone.  Decided to purchase four new probes.  According to the Rhode and Schwarz website, I could purchase new probes directly from the company.  Support told me as an individual, not a company or part of a company, they could not help me.  Something about being in the process of changing the way they deal with non company purchasers.  Maybe US market only.

Considered some other options, but decided on OEM probes.  The only place to purchase these in the US currently is TEquipment.  So I ordered four RT-ZP03S probes.  The image, description and specs listed were exactly the same as RT-ZP03 probes, 1X/10X switchable attenuation.  Upon arrival I found the RT-ZP03S are actually 10X only, and all three waveform adjustments are now inside the small enclosure at the BNC connector.  They work, but I really do prefer the switchable attenuation.  Possibly the original RT-ZP03 are no longer made.

Part of the reason I purchased this scope for the higher cost was the claimed superior support.  Other companies may have the same protocol.  Nonetheless my last Rhode and Schwarz purchase.

Russell

10

Beginners / Re: Is it safe to store CMOS devices in the AideTek ESD Boxes

« Last post by shabaz on Today at 04:59:27 pm »

It may get unscalable when everything is stored in individual small compartments. Personally, I leave ICs in their original packaging, and just write with a permanent marker in case the labels fade, and place them all into a box (over time, you could have a separate box per project or separate boxes for (say) analog ICs, discrete semi, digital. Some boxes are long and about the right size to keep all the packets tidy-ish if you prefer that. For anything in tubes, personally, I use a small waste bin (well, slightly nicer than a typical waste bin! It is woven to look not so ugly) and place them all in there (in their original packaging again).

For general practicality while experimenting (i.e., not production), I do have little conductive plastic pots with lids in a couple of small shallow tray-like boxes with lids. These are useful for your most popular devices, e.g. low-power (SOT-23 or similar) BJTs, MOSFETs, diodes, jellybean stuff etc, so you don't need to keep trawling through large boxes for those. But possibly it's still a bit excessive, a simpler option would be to keep a small box of popular parts in their original packaging. Whatever you feel is more practical for you. You can also place conductive foam in ESD-safe tray-like boxes if you have popular through-hole parts.
 
In your case, since it is a specific lab kit, you may wish to do something different for even more practicality perhaps, but I'm not sure there's any single optimal way. One reasonably practical way that I saw was the Digilent component kits. They use a cheap (non-ESD-safe) clear transparent plastic box with dividers, and for the ICs, they shoved them in foam and inserted them into compartments (also, in the photo, notice the chamfered corner on the foam; that's for lifting out because there are more ICs in another layer of foam below). Obviously, this is not good for production use, as there is still a risk of damage, but for learning/experimentation, I think it's a fairly reasonable solution to obtain a large box with many compartments and a large sheet of conductive foam and cut it up. If your lab kit is really massive, perhaps it could be split up into two or three categories, each in its own large box.