Is there a reason the uCurrent Gold doesn't have a port for a 5.5V wallwart? - Page 1
Forum section: electronics / beginners

author: Montzterrr
author_rank: Newbie
timestamp: October 14, 2014, 10:47:44 pm
content: So I was looking at the uCurrent again, and it says it can use up to 5.5 volts instead of the 3 volts from the coin cell, which would provide up to +-2.25 amps of range. Is there a reason there is no connector (like a 2.5 mm jack for a wall wart)? My guess is it is either because it is shipped globally and getting the right connectors would be hell, or the 50/60hz noise from the mains would destroy the specs of the device. Would it be recommended against modifying the schematic to include a connector for a walwart and just use a power supply with 5.5V?Schematichttp://www.eevblog.com/files/uCurrentRev5schematic.pdfhttp://www.eevblog.com/projects/ucurrent/

author: lapm
author_rank: Frequent Contributor
timestamp: October 14, 2014, 10:51:48 pm
content: My first bet would be isolation. You hook up wallwart thats extra ground path... As battery powered, uCurrent can float since it has no "ground" reference..

author: Montzterrr
author_rank: Newbie
timestamp: October 14, 2014, 11:10:14 pm
content: So would you recommend using a 5V LDO regulator like thishttp://www.digikey.com/product-detail/en/LP2985-50DBVR/296-20717-1-ND/1169352and use 4 AAA batteries to power it?

author: nukie
author_rank: Frequent Contributor
timestamp: October 16, 2014, 10:20:47 am
content: Just hook up a cheap lipo pack from any mobile phone and you are good for many hundred hours.

author: krivx
author_rank: Frequent Contributor
timestamp: October 16, 2014, 10:46:13 am
content: QuoteThat's probably why. Longer than many handheld multimeters, and the uCurrent isn't going to be in use for hours at a time for most users.

author: george graves
author_rank: Super Contributor
timestamp: October 16, 2014, 10:48:51 am
content: Quote from: nukie on October 16, 2014, 10:20:47 amGreat idea! Cheap, plentiful, and even a used pack will give you more then 10 hours. Plenty of room in the case for sure. Maybe Dave will prove solder points for it in the future. (he for sure won't be shipping lipo batteries!)The down side of a pcb as a front panel of a box, is that it's so light weight, it doesn't stay in place...and ends up all over the workbench with a tiny bit of test lead moment. On some test rigs, I've taken to mounting them to a chunk of 3/4" MFD for some mass, and some 3m rubber feet. Keeps things nice and stable. So a battery, (and maybe some other weight) would be welcome!

author: nukie
author_rank: Frequent Contributor
timestamp: October 16, 2014, 10:58:29 am
content: Quote from: krivx on October 16, 2014, 10:46:13 amI always rely on the auto-off function of my dmm, to avoid wearing out contacts. So I had to install a 3000mA lithium to solve my ucurrent issue. Also included a charging port when it's empty. Before that it never sit in the box, the screws were never put back.

author: SeanB
author_rank: Super Contributor
timestamp: October 16, 2014, 05:51:17 pm
content: Solved the mass problem simply by placing a half dozen CR2032 cells inside, still in the blister packaging. Now it stays more or less still, and I know where the spare cells are.