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Test Equipment / Re: Power supply for home lab - do I really need a R&S?

« Last post by J-R on Today at 10:32:55 am »

Overall the E36313A is pretty great, with its available rear outputs + sense but you'd have to find a used one to have any hope of reaching the target price point.

Biggest flaw in my opinion with the E36300 series is the front panel control knob UI. You can't select a specific digit to adjust up and down, so you're left with a somewhat crude acceleration feature. If you want to do 100mV steps, you would need to program it to do that. I use the keypad exclusively so no issue personally and I have other bench supplies with better knob UIs.

The GPP-4323 isn't perfect either, there are reports of recent firmware issues as well as some other items. Also, the load feature has some limitations, such as 1.5V minimum operating voltage.

Could also add Rigol to your list.

Repair / Re: Please help, how can I adjust this transistor?

« Last post by daisizhou on Today at 10:23:33 am »

I measured the voltage between GND-R1 and GND-VR1,If you mean the voltage between R1-VR1 please tell me and I will re-measure.
thanks

Microcontrollers / Additional high res. PWMs by using Configurable Logic Cell (CLC) block?

« Last post by jm_sanz on Today at 10:14:53 am »

Good morning,

I am in the design phase of a SMPS GaN based that will operate at around 1MHz with many four-switch Buck-Boost (FSBB). Most of the MCUs for this kind of applications only have 8 pairs of high res. PWM (around 150ps) but I need more. Having an MCU with more high res. outputs increases its price significantly.

I have thought of using the “Configurable Logic Cell (CLC)” that many of these microcontrollers have for generating complementary outputs and only using one pair for every full-bridge thanks to some logic.

I found an Application Note from Microchip Technologies that talks about this possibility in Fig. 11.
https://ww1.microchip.com/downloads/en/AppNotes/00002133a.pdf

dsPIC33CK include this block:
https://ww1.microchip.com/downloads/aemDocuments/documents/MCU16/ProductDocuments/DataSheets/dsPIC33CK1024MP710-Family-Data-Sheet-DS70005496.pdf

What do you think about this possibility for high frequency application? Feasable?. I am afraid about possible delays this block could produce but cannot see why it would not work.

Best regards,

Miguel.

Metrology / Re: LM399 based 10 V reference

« Last post by Birb on Today at 10:12:54 am »

Ok, so I've modified the circuit to add the overcurrent / overvoltage protection like the example shown.
However, based on some simulations, it seems that the 10k resistor also should be quite stable, as it can affect the output voltage.
Also, are the LM78XXs suitable for this? Or should some other linear regulator be used?
Thanks!

Metrology / Re: Is anyone into quantum technologies and quantum metrology?

« Last post by zrq on Today at 10:11:43 am »

Well, not necessary true. For many cold atom experiments one don't need cryogenics, but in fact a heated oven to generate a beam of atom to be Zeeman slowed and loaded to a MOT.... For the projects using warm vapor it's more obvious.

Microcontrollers / Re: RIP Z80

« Last post by peter-h on Today at 10:06:11 am »

Aha I did see that project but on a quick look didn't realise they actually put it in an FPGA.

The EP2C20F484C7 is GBP 102

and they are using 11% of it. The Spartan-6 6x1s16csg324-2 I could not find. The devkits all list as obsolete.

Yes; this is what I found years ago when looking at FPGA versions of the TMS9900 UARTs. Very expensive back then. The UART used up a chunk of a GBP 200 Xilinx 4k FPGA.

So to be doing this, you would probably be working on a project which needs a big FPGA anyway, and there aren't many of those. I see things like $5000 ARINC429 interface cards using 3 digit priced FPGAs...

It is not efficient to use FPGA logic structure for a design which was totally hard-wired.

Beginners / Re: Buck-Boost converters and the details of the inductor (field collapse)

« Last post by soldar on Today at 10:04:57 am »

I am not sure what you are asking. The inductance stores energy and then dumps it into the LED. If the LED is 2.8 V then that is what you will see.

Test Equipment / Re: service manual

« Last post by coromonadalix on Today at 10:00:27 am »

ask velleman ?

Sold iunder this name Velleman DVM645BI

and maybe other names ...

https://cdn.velleman.eu/downloads/1/dvm645bisoftware.rar
control software attached. remove the txt extension it's a rar file

the best thing is open the meter and search for the main dmm ic many Mastech have Fortune Semiconductor, or maybe Cyrustek ic's

examples here : https://sigrok.org/wiki/Multimeter_ICs

Buy/Sell/Wanted / Re: Canceled Because Thread All Shit Up by "tggzzz"

« Last post by coromonadalix on Today at 09:57:13 am »

And now since all has been said / written, i think this thread can be left alone .... 4 pages is enough

if i was a mod i would close it

Test Equipment / Re: DHO924S vs MSO5074 vs SDS804XHD+AWG

« Last post by Muttley Snickers on Today at 09:57:02 am »

I forgot to mention that you can edit or modify your post at anytime to add or delete text, images, links and so on... Once your post is quoted though it virtually becomes the property of others so it always pays to do a proper proof read before posting, otherwise someone might quote your post before you get a chance for an edit. Also, I'm not a moderator here, just a dodgy member so best to read the rules.

In regards to the test equipment, I am also looking to purchase an SDS804X HD, SDM3055 and either a SDG1032X or SDG2042X, undecided on the latter and there are some good threads about on comparisons of these models. I have also noticed a few other local members pondering over similar acquisitions and wonder if some are just waiting for a better deal or certain models to go on special, which very rarely happens down here. I am not in any rush and need to feel like I'm getting a good deal before handing over the cash, this practice becomes habitual with business.