It was in late 2021 when I was browsing ebay for a decent LRC (or RLC) metering device. Originally, I thought I'd go for a cheap-ish digital one, but then this little gem of a retro device popped up for rather cheap. It was cheap mostly because it was untested and had at least one stuck knob. Sounds like a challenge to me! The device itself is based on a Wheatstone / Wien bridge circuit and allows very precise measurements of resitsors, capacitors and inductors: R, C and L. I always mix up the sequence of these letters in the product names and I'm sure there are multiple versions out there... LRC? RLC? Doesn't really matter: all three of them! I did the usual recapping and cleaning, although internally not much cleaning was needed. Wow. It looked brand new inside! I am also not sure if the device originally came with a cover; the case has attachment points for something along these lines on the side, but the manual doesn't indicate one way or the other. Making one might be a neat build project at a later time maybe. I'll keep it on my list of things to do! It would be interesting to see how accurate the thing is. If I ever get to some calibration lab, I'll be sure to bring it along. All test measurements were agreeing in magnitude and first significant digits with my other means of checking them. The 3rd and 4th digit is where I can't confirm anthing sadly. But since I didn't change anything on the precision resistors and the reference cap, I'd assume it's at least in the "more than OK for hobby use" range. And before you ask: yes, the "restored by Atkelar" sticker is ever so slightly crooked again. At some day I might get lucky and manage the proper alignment before the sticky side starts to stick to a freshly painted case. 0:00 Intro / Presentation / Inspection 1:31 No Batteries? 2:05 Open Case / Shiny! / Strategy 3:16 Golden Tin Can? / Binding Posts 4:28 Triple Potentiometer 5:16 "Dekastat(tm)" 5:46 Cleaning / BNC / GAIN potentiometer 6:57 D-Q Potentiomater Assembly / Recapping P2P 7:42 Strange Capacitors 8:21 Delete Charger / Battery Tube 9:51 Case Refurbishing 10:42 Reassembly! 11:40 D-Q deba-q-le... 12:22 D-Q wiper adjustment / Tidbits and Dials 13:17 Chassis Layer 2 13:55 Test #1: Batter Check 14:11 Bridge Circuit, Rough Theory 15:36 Resistor... 16:21 Capacitor... 17:18 Inductor Measurement 17:38 D/Q and ESR math overview 18:57 Case Finish 19:51 Done! Overview / Bye / Credits / Outtakes Music: My Train's A Comin' Unicorn Heads (YouTube Audio Library) You can support me on Ko-Fi: https://ko-fi.com/atkelar Useful links that I found via Google that were helpful for this project: Wheatstone Bridge: https://en.wikipedia.org/wiki/Wheatstone_bridge Wien Bridge: https://en.wikipedia.org/wiki/Wien_bridge Historical account for the Wheatst ... https://www.youtube.com/watch?v=_BR6oW8zcMg

Restoration Project #30 - HP 5036A µLab This one is a restoration I'm doing for a friend, Karpour. He's also into collecting old school nerdy stuff and occasionally asks me to fix some of it. I was quite honored when he asked to prepare one of his more obscure devices: a late 1970s microprocessor training kit from HP. The board was complete, with the exception of the speaker, but commpletely missing the original suitcase and power supply. There is very little documentation out and about, the "service manual" lists all the components, but has no circuit diagram. This leads me to believe that the original training manuals had that already in them. HP also made use of a weird "diagnostic tool" (which they call "signature analyzer") that seems to count pulses of logic signals and could be used to detect anomalies on chip inputs or outputs. But the numbers that are listed in the service manual are totally useless unless you have the matching tool. At any rate, I had to do some reverse engineering of the circuitry in order to find out what was wrong with the device. And, oh boy, was there somethong wrong... Two logic chips and both SRAM chips were broken. It took quite a bit of tracing to find all the faults. Not to mention, that the board was designed to educate... and that includes "fault simulation" on the board via some unlabelled jumpers. It was much easier, once I found out that these jumpers were supposed to introduce faults; my reverse engineering was hampered quite a bit because I could NOT make sense of some of the options they selected... But overall, I managed to get the board running again and could finish the request to make it into a functional display piece that can be hung to a wall as well as used - even on the wall if you so choose. NOTE: soldering and desoldering was a nightmare: the PCB is 2.5mm thick (1/10") and to get the solder up to tempereature for a nice connection or desolder job is almost baking the chips, especially with the VCC/GND rails, which are extra beefy and thus extra thermal sinks... Another note: @Adrian's Digital Basement ][ recently had a video about a "free run" CPU tester for 68000 CPUs; while I only ever saw it on this board here myself, his video makes me think this might have been a common diagnostic tool back in the day... would be interesting if any other devices had something like that to do a "quick check" of the processor? 0:00 Intro / First Diagnostics 2:20 Address Bus Problem / Recapping 3:40 Customs Delay / Buffer Replacement 5:07 Second Diagnostics / ROM Dump / 74LS138 6:05 Third Diagnostics / Data Bus / IO Chip 6:45 RAM Maybe? / SRAM Test Botch 8:19 DIP and Jumper Description / 9:05 SRAM Update / Keyboard Matrix Problem 10:05 Board Cleaning / Speaker 10:58 Case Construction / Backer Board ... https://www.youtube.com/watch?v=0fCSlPqSJKk

The complete set of the intro videos I did for the Fursuit Gameshow at Eurofurence 22 - It is of course meant to be a "Max Headroom" parody, including the kind of humor and "I don't give a ***" attitude. People who don't know the original might not like it, so check out some of the Max Headroom episodes for reference first ;) ... https://www.youtube.com/watch?v=gKIQDbfbVhE

A little something I came up with, as a parody around current events... at least right now it's still parody. I didn't have enough time to finish this so the lighting is not the best I could have done and there's some "close ups" missing that I would have loved. Comment on the Vimeo version https://vimeo.com/79642872 while YouTube comments are still broken. ... https://www.youtube.com/watch?v=D8DAFpvqBtQ