I'm a hobbiest working my way back to being an EE. I got a degree decades ago, but did software professionally instead, so I'm extremely rusty, but working on it... Heh. I've been building up my home lab over the past year and I have a current project that might give me plausible justification for a ~6.5 digit bench DMM. Ebay has some claimed "working and calibrated" HP/Agilent/Keysight older models for around $400 US, but I'm attempting to make sure new/used equipment I buy has LAN whenever possible. Plus I'm still too rusty to adequately deal with a boat anchor at this time.
Part of my current project (AKA plausible justification for test equipment purchase) is to build a "germicidal UV power" probe as simply and cheaply as possible, since it is not the intended goal of the project just the means to measure and verify to main project. "Real" equipment for this type of measurement run around $2k to $4k to purchase or about $250/week for rental. So, if a bench DMM will work, even a SDM3065X will end up being cheaper since I have no long-term use for measuring UV power. If interested, the project I'm currently working towards is linked here, but I have since realized that measuring material reflectivity/absorbance/transmittance using a DIY test jig is also needed beyond just measured UV power from a bulb (when you don't have a spec sheet):
https://www.eevblog.com/forum/projects/cheapest-way-to-check-if-a-uvc-bulb-is-as-advertised/msg3000790/#msg3000790Feel free to correct me if I'm wrong thinking that a 6.5 digit DMM would work for my needs, or if I should be looking elsewhere (
I don't want to hijack this thread).
A few questions about Siglent bench DMMs.
New firmware for SDM3065X
Version V3.01.01.07
[SNIP]
Release notes
1. Add customer defined senor function
[SNIP]
Does anyone have more info on the customer defined sensor function? Is this a common feature of modern bench DMMs? The photodiodes on digikey that are responsive to germicidal UV (~200nm to ~320nm) tend to be in nA territory, although my rusty EE skills may have misinterpreted. So my thought is to shortcut building a full UV probe with instrumentation opamps/etc and just use an accurate-enough bench DMM with the raw photodiode + PS + optical filter if necessary for specific photodiode. If the firmware of Siglent's DMM can calculate the actual result from coefficient * (measurement - offset), then that would be very nice to have. If the idea in my head on how this feature might be used is wrong, feel free to correct me.
I'm curious about the scanner card option.
Does anyone here actually have a unit with scanner card that might comment on it? AFAIK, the only drawback is the reduced number of measurement ranges when using SC channels, but you still have the full 6.5 digit accuracy within those ranges? From my perhaps incorrect perspective/use, the SC option is equivalent to a large pile of individual high-accuracy DMMs that are all accessible via LAN. Seems like a "cheap" way to dramatically increase the measurement capability of my lab.
Does firmware support using the front panel measurement "channel" while in scanner mode yet? Would be useful to use front panel input for very low amp range UV sensor while monitoring UV bulb voltage and current using the wider ranged SC card channels. Yes, it would be better to make a fully functional UV power probe and do all of this with a scope, but I'm attempting to minimize the effort for a short-term project.
I've seen the SDM3055 hacking thread, which seems as much about HW mods as FW.
I'm curious if anyone has "improved" an SDM3065X with practical results, as in more non-noise digits of precision, etc without HW mods?