HP3468A Multi-MultiMeter project - Page 1
Forum section: electronics / projects

author: intabits
author_rank: Frequent Contributor
timestamp: August 22, 2025, 05:10:32 pm
content: I have three HP3468A multimeters, like this:-But I don't like the non-backlit LCD display, so I came up with this prototype solution:-This was a couple of years ago, and I described it in this thread:-https://www.eevblog.com/forum/projects/replacement-front-panel-for-hp3468a-multimeter/msg4663885/#msg4663885(includes link a video showing it operating)I was quite surprised that my post didn't attract any responses, especially as the thread that prompted it went on for about 7 pages...Anyway, undaunted by that, our hero forged ahead regardless!The prototype attempt I made above was quite fiddly to fit to the original HP3468A case, and I wasn't at all happy with it.So I thought about putting them all in a new cases, which would also allow them to be stacked (which the HP case doesn't allow).Which also prompted me to recall that I'd often seen scenarios like these:-From Dave's video #957:-And another on Smith Kerona's channel:-Which provoked a flash of inspiration - Why not put all 3 meters in the same box (plus room for a 4th)The result: A Multi-MultiMeter!Having the meters closely coupled allows synergistic possibilities.The obvious example would be measuring power supply input and output voltages and currents then calculating power in and out, and from that, overall efficiency.I've come up with a tentative design, shown in the following images:-(missing: there should be a shield between the front panel and the meter stack)Here's the block diagram (but ATMega1284 controller chip would probably be ATMega2560, or maybe RasPi Pico):-Approximate dimensions are:-234mm Wide 9.2"280mm High 11"330mm Deep 13" (including 10mm top and sides front panel overhang)I'd be interested in your comments, ideas and suggestions about such a project...

author: pqass
author_rank: Super Contributor
timestamp: August 22, 2025, 11:56:37 pm
content: In my opinion, that's a lot of work. Also, gutting a nice instrument rubs me the wrong way.What are you saving? Maybe an extra 2RU height?The enclosures aren't stack-able but you could remedy that with 3 flat metal (1") strips on the back and sides (held by captive nuts inside).Then I'd just build anHP-IL translation box(no magnetics required) to a desk console (large display+keys) or PC.

author: intabits
author_rank: Frequent Contributor
timestamp: August 23, 2025, 05:51:31 pm
content: Thanks for your input.Yes, it would be a lot of work. But I see that as a challenge. For me, this is a project in and of itself.I'm not looking for just the simplest way to get an improved display, and to use 3 or 4 of these meters together. Instead I want to make I consider the best way to accomplish that.I don't place much value on their current implementation, so gutting them to do this is fine by me. But nothing I plan on doing to them is irreversible.As to size, the standard HP3468A case dimensions are:-220mm Wide 8.7"095mm High 3.75"275mm Deep 10.8"Which is a volume of 5.75L, and 23L for four units.The enclosure I described earlier has a volume of 14.5L, so that's a significant reduction.For 4 units, it's 14mm wider, 55mm deeper, and 100mm shorter.Here's a shot of a simple text and graphics display demo video showing the sort of sort thing that I envisage for the 7" LCD. Which I believe could be a vast improvement over the existing displays.And this improved display comes in a standalone unit, with no need for a PC to get it.Interesting HP-IL interface there, I've never looked into using HP-IL.But that shows another advantage of my multi DMM box - just 1 power cable, 1 PC connection, and no dongles.