Tag: 4mm banana jack

CEM DT-9939 multimeter leads (WHL #88)

Just an oddball thing that I discovered this week when lending out the leads of my newest multimeter, a CEM DT-9399. While the unit was an absolute bargain for what it can do, and the only thing to complain about is the slow continuity test mode and the slow Wireless USB (!) data transfer, this post really is about the boring leads. They just happened to be the only ones around in the office, and the boss asked for a spare multimeter that he could take home for the weekend for some rudimentary electrical testing, likely on an AC device. Well, better safe than sorry, don’t hand over the regular (non-safety) 4mm leads with some add-on test prods – give him the leads that came with the 1000V CAT III/600V CAT IV meter, right? […]

HP 6644A refurbishment – front panel, back protector (#P14F1)

Time to finish the HP 6644A revamp!

tl;dr for the last post: Here’s where I stopped refurbishment after cleaning and replacing caps and fan:

First off, those leads stick out quite a bit at the back as well. I can’t really say which diameter I used, judging from the yellow cable lugs these were 4mm² for the power lines and 1.5mm² (red lugs) for the sense lines. Apart from not fitting the old protector, that one already has seen some damage. Probably because it is so tiny…

So: Redesign. Twice, as the first version that closely resembled the original design had really flimsy legs that suffered the very same fate. […]

7 decade thumbwheel resistor box (project #P1)

A while ago, I wrote articles about a bargain SMD resistor set (WHL #10 ) as well as some thumbwheel switches (WHL #11). Let’s start fresh in 2017 and present the final box :)

As already shown in the thumbwheel post, the initial resistor placement wasn’t perfect. I fiddled some more and I got a case and nice 4mm banana plugs for it. First, let’s see the final measurement results, done with a calibrated Keithley 2700 6 1/2 digit DMM in 4-Wire (Kelvin) mode.

Original performance:

Final performance:

Yep, the 1Ω data point still violates the 1%/10000ppm spec (1,9%). […]

Shootout: Antistatic ESD Wrist Discharge Band Grounding Prevent Static Shock Red vs. Pollin ESD Wristband vs. Vermason (WHL #3)

Pew pew!

Today, I have some ESD wrist straps ready for testing. While everybody in electronics is aware of the magic smoke escape problem (once it’s gone, it is very difficult to fill it back into your IC), electrostatic discharge (ESD) protection isn’t always first priority. I do save you from links to an east european “hacker” that employs high standards in this area ;) However, I’d like to link to NASA and the chip manufacturer Maxim that have some helpful sites about ESD. And, trust me, they do care about reliability of their products – which is why they do their best to prevent component defects or weakening by ESD. […]