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Love this, honestly it's a really great hobby because with a few components you can make things that do things and you have something tangible. Seems @Touring_Rob got you on the right path! I know that it's hard to get over the "Chinese made crap" thing, but they really do crank out decent...

Off topic…but it’s my thread…:) Saturday I built up the LTZ1000A reference, there was a definite squeaky bum time when it came to soldering the reference. Currently it’s hanging off the front of my top 34401a and also fed into the second one, horrible cabling and no shielding although I did...

Yeah, I’ll patch in a 20-bit one, it needs MOSI (to do anything other than just return conversions) but all the digital signals to the analog board have bidirectional level translators it’s easy to patch that onto the ADC and I can try both feeding in the raw + amplified signal.

I will also do some tests with the LTC2480 as the main ADC since it has a programmable gain amplifier built in, although it’s only 20-bit, I can stretch those bits further than I can on the 24-bit, it may be a better solution. It’s also cheaper and availability isn’t an issue. The analog board...

this project has been a real godsend in keeping my mind occupied over the past month, I have made a couple more changes, so one of the sense resistors is lifted and there’s an additional 100 ohm resistor (well, it’s 2 50ohm in series) on the rear and a trim pot. I broke out the measurement...

Got some DPDT relays coming over the next couple of days, I don’t have stripboard or JST XH connectors here, left them all at home…..so had to buy another set of them, and another strip board cutter, and stripboatd, and 2.54mm single in-line connectors and….you get the picture, all stuff I have...

sometimes you can’t beat pencil and paper, or in this case, ipad and Apple Pencil, it’s way easier to noodle parts or ideas on the iPad than it is sitting in KiCad trying to find parts, put wires and so on. since deciding not to move all the calibration stuff to the analog board, I grabbed a...

f**king KiCad strikes again, I’ve seen this before, a net that for whatever reason it decides to not connect between sheets, it’s done it before to me and it did it again on this. The 5V ref on this is powered directly by VIN, it decided that VIN on two different sheets were not connected, and...

I'm a f**king idiot. I reposted the same link. This I what I meant to post. https://www.edn.com/dc-accurate-32-bit-dac-achieves-32-bit-resolution/ It uses the sum of two PWM signals to produce a "32-bit" DAC, one is a coarse PWM and the other is a fine PWM and I've seen this article cited in...

Yeah…my brain is all over the place. https://xdevs.com/article/kx-ref/ The stability is the big thing here as you know, especially where the TC is concerned, this design is apparently very good, the LTZ1000ACH is used in the 8.5 digit meter HP/Agilent/Keysight have sold that I’ve forgotten the...

My mum is in a hospice now so I have plenty of time sitting with her while she sleeps. @Touring_Rob have you ever seen this design? I’m going to recreate this, I have a LTZ1000ACH on the way from mouser and I have bought the other parts for the xdevs design of the LTZ1000 7.1V based reference...

So as expected, the isolator didn’t work, I didn’t expect it to but it was worth discounting, I actually lost my previous isolator so needed another one anyway. I did look at the ADC results since I have no equipment here and I suspect it’s noise or ripple caused by the USB IP in the RP2040...

as mentioned, the tolerance pages will be configurable, add as many as you want, they’re a convenience for checking a resistor is “in spec”. When it boots it goes straight into the measurement page, this shows the the measurement that’s under way, it also shows the average and minimum and...

I've done a crap load on the UI overnight, back at my mothers because she really isn't very well so this is actually a welcome distraction. I also did a load of refactoring of the code, I'm gradually abstracting parts out, moving bits into their own classes since this is still running on a...

So I've now started to actually start fleshing stuff out. I finally hooked up the rotary encoder, I also wired the "reset switch" on the back of the unit to TP6 on the rear of the pi pico board because the flashing is so f**king flakey with this crap "uf2" mass storage mechanism, it's no...

I’m toying with just sticking an ESP32 in there that runs independently, I’ll then connect to this via a opto isolated 232 (ttl level), job done, they’re peanuts. this currently has a pi pico in it because I had one on my desk, the graphics library I found used arduino (still ducking hate it)...

Need to buy a few more values of the vishay dale resistors I bought a few values of, I have a 5 mOhm under test, these resistors specify the distance from the body to the leg where the connection should be made, since on a milliohm range fractions of millimetre will alter the reading. The...

I do have filtering on the input to the ADC, but I haven't really played with the input filter since I have flying wires, and components waving in the air, none of which is conducive to a low noise floor, I might try upping the cap to a larger value but when the rev. 1 PCB arrives I can take a...

I'm not using the gain on the 1991, it's configured for 1:1 purely to convert the differential signal to a single ended for the ADC, even on the op-amp stage I'm only running with x10 gain, the BB opamp I was using was a fixed gain one, I can at least now modify the gain on the op-amps with the...

That's a very good op-amp, so good on paper that I've decided modify the finished R2 design and replace the BB op-amp since I can then do comparisons, everything in GIT so it's easy to revert back. nearly every part of analog design is using LT parts now, apart from a rail generator for +/- on...

I knew you'd ask that! And yeah, I've considered it, I can probably squeeze in a header to an external relay and put solder bridge jumpers (NC, i.e not using relay) to select between them, there are solder bridges there that allow me to bypass the FET's anyway since I don't know the exact...

My mum is unwell at the moment, we're staying with her and to keep my mind occupied I did a load more changes to the hardware. I've added a bunch of FETs to allow me to perform calibration without interaction from the user, I can now disconnect the force sense cables and I'm now able to...

I’m not unsurprising news, here’s the first push back, from 1st March to 8th of May…. I’m not entirely hopeful on the new date.

it’s not a massive issue since in reality with point proves you’re measuring in a relative way, you are measuring across a two nets (vcc and GND) to find the smallest value, since you probe across components if the value goes up, you’re moving away from the short, you’re always going in the...

Haha, I’m a bit humbled that this has has piqued people’s interest. When the proper PCB arrives I’ll be able to see how far I can push this hardware, I may consider just releasing the hardware design and code, there’s a few expensive (well relatively) parts on it that currently can’t be bought...

I've also printed out another case section (8 hour print!) and bumpers except in blue this time, I'm going to quickly knock up a board with various precision reference outputs with an input as well, same LCD as on this I'll show the reference voltages but also the differential between a specific...

I bought this a year or two back: https://lowpowerlab.com/guide/currentranger/ The back story to this is that I created a humidity monitor for filament dry boxes for 3D printer spools (I'm pretty sure I posted about this), it used an ESP32 and a e-paper display since this allowed me to display...

Just as an aside, since you're clearly into this geeky stuff (although this is probably more on the nerdy side). CERN released the design that they use on the LHC for a 8 1/2 digit volt meter... I watched a video on it late last year and some guy built one! Not for the feint hearted. Not...

btw, the 24-bit ADC is actually 28 bit, but they qualify it as a 24-bit ADC and that the lowest 4 bits are actually sub codes, you ignore them unless you want to make use of them in averaging, it's not described as a 28-bit ADC, it's somewhat of a surprise to find that's what it actually is when...

Ha, no worries, I thought it might be of interest to a few peeps in here. Yeah, 16-bit won't cut the mustard! The actual "sense" measurement is taken with a 24-bit ADC operating in single ended mode, the reason being that it's fed from (what was a burr brown) differential precision fixed gain...