Recent Posts

1

Beginners / uCurrent Gold Schematic

« Last post by uf29857 on Today at 03:55:58 am »

I am working on my university project to design current meter to measure currenst from nano amps to 3 amperes positive DC only. Design is based on Dave's ucurrent gold and videos designing a better multimeter. Components being used are, MAX4239,CSD16340Q3(NMOSFET), ADS1115, ESP32 ucontroller. Charging circuit for battery, and usb to uart (CP2102). I have attached my schematic. Please review it and feedback will be highly appreciated.

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Projects, Designs, and Technical Stuff / Re: "practically smallest" debug connector on tiny pcb

« Last post by Kasper on Today at 03:54:10 am »

If you include an extra pin, you can use it as a key, to reduce the chance of someone plugging the programmer in backwards.

3

Microcontrollers / Re: RIP Z80

« Last post by CatalinaWOW on Today at 03:50:13 am »

The high volume markets drive the chips (and the SW toolsets).  The low volume folks have to dodge around and try to figure out where the high volume people are going so that their choices will meet their market needs.  And there is a big split in the low volume market.  Those who will be producing for years or even decades, and those who make a production run or two and then move on to the next model or product.  That first group is the one that really needs to be clairvoyant or clever.  Fortunately many of those old chip designs can be adequately emulated on current hardware allowing transparent to software and user replacements for ones that have gone EOL.

4

Security / Re: Microsoft repackages apps with a telemetry .NET wrapper

« Last post by helius on Today at 03:33:52 am »

Of course corporations want to make believe that their spyware (ahem, "telemetry") is the equivalent of a usability study, but it plainly is nothing of the kind. Collecting statistics—on which buttons are clicked most often—doesn't yield any useful information if there is no experimental control. Data without a control is just worthless junk (see most papers in econ and nutrition for examples).

The UI changes that they justify on the basis of this worthless junk are also, you guessed it, worthless. But everybody already knew that if they are remotely familiar with user interfaces in the pre-2005, and compare to what dreck is pushed out these days. There are other reasons for the widespread UI failure ("responsiveness" and touchscreens are a large component) but reliance on uncontrolled UX data collection is surely a major factor.

5

Metrology / Re: ESI RV622A Resistor Repair

« Last post by scopeman on Today at 03:17:30 am »

That wire is probably manganin or something simiar.

https://en.wikipedia.org/wiki/Manganin#:~:text=Manganin%20is%20a%20trademarked%20name,the%20Bushy%20House%20physics%20laboratory.
https://www.isabellenhuette.de/fileadmin/Daten/Praezisionslegierungen/Datenblaetter_Widerstand/Englisch/MANGANIN.pdf

I am not sure what flux to use but when you find out please post. I saw on YouTube (search soldering Magnanin wire) where it looked like regular tin/lead solder was used but there were  no other details available. I do know that once you fix it you need to coat the solder joint and the exposed wire with a conformal coating to seal out oxygen.

Sam
W3OHM

6

Power/Renewable Energy/EV's / Re: SMPS input filter cut off frequency

« Last post by coppercone2 on Today at 03:14:41 am »

I looked at snvA 801 and its written so poorly it makes me not want to read it at all 

i dunno if its auto translated from another language or what

I would definitely not try to learn from those Ti app notes, that is a shady reference document for people that know most of it is

just do what vicor tells you to do and don't do what Ti says unless you think it can improve something? god that app note is fucking irritating. that is something you pay someone for reading so you don't need to read it

7

Test Equipment / Re: Siglent SDS3000X HD and upgraded SDS1000X HD

« Last post by KungFuJosh on Today at 03:07:27 am »

Nice! Biggest issues I saw:
5:05 didn't know the difference between the internal LA hw or external LA hw connections...
11:32 still didn't know LA hw is external, assumes the zynq chip is handling the LA stuff.
If you don't want to RTFM, look at the product page quickly and you can see the external logic hardware listed.

8

Beginners / Re: What function generator, that does a bit more than just a simple signal

« Last post by johansen on Today at 03:07:16 am »

Seems to me you can do a lot of this with a second pulse generator and some additional circuitry.

Most signal generators are 50 ohm output and it is ok to short them out and over ride them with a lower impedance on a short term basis. For example if you want to trigger a glitch by holding the pwm high for just one cycle. Use a second triggerable pulse gen to pull the signal high with a mosfet, with some additional circuitry to enable amd disable it as a one (or n) shot timer.

For adding noise, use a resistor divider to mix in the spikes.

9

Repair / Re: Desoldering advice

« Last post by antenna on Today at 03:03:20 am »

I thought I would get to it today, but I didn't.  I did manage to find my big soldering iron tips for the propane torch, so I will give that a try.  My soldering station has an IR preheater, so I will do as suggested and get it warmed up before taking the soldering torch to the leads.  I may just replace the electrolytics and not worry about overheating them.  Tomorrow is supposed to rain all day and I need a break from what today has been, so hopefully I will have that relay out.

Given my next attempt will be with a much larger soldering tip and using preheating, what would be better, adding regular solder to transfer and hold the heat or trying more low MP alloy? 

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Power/Renewable Energy/EV's / Re: Totem Pole PFC is over-hyped?

« Last post by coppercone2 on Today at 02:47:04 am »

I think you need to invest in some power electronics lab and prototyping abilities to test some stuff because it seems like a big mess of theoretical spaghetti with this. hiding behind cost frowned upon in this forum, people here seem to figure out ways to do things that are hard

but, what stands out for me in this thread, as famous last words, is "software is not a issue." Hand wave a issue because a big number popped up and then follow that up with some figuring about the competition (and assuming their sane). A level V systems engineer wrote this?

some tips:
1) buy 10
2) make the circuit board repairable, modular, thick, whatever so when 1 explodes you don't go into cad crisis mode spamming the forum about simulators because some fragile ass prototype exploded unrepairably
3) attempt common sense based trouble shooting