2023. szeptember 16., szombat

Building my rack(s)

In my previous lab, I had a small (27U) rolling rack at the side of my desk. When it finally got its shape, I started to move to my new lab. The equipment removed the rack disassembled.

I was a bit depressed on this as I had the feeling I'll never be able to put this together once again.
As I was reading things on the Facebook, I seen a guy trying to sell a whole bunch of outdated Cisco networking equipment. Nobody was interested, there came ugly comments on it, to throw the whole thing to the trash.
I seen a potential on something. Those Cisco units were installed into rack. So I wrote to him, if the rack containing the switches are on sale.
So I've two Rittal 42U height 600x800 racks for $100 each. I had some cleaning, metal work and paint repair with it (full repaint wasn't required, it has almost no rust just some dirt). One set of the vertical rails are not compatible, one rail mount was missing. Also I wanted open frame rack, so removed all of the doors, side panels, back panels.
Also I wanted to be able to move it on some rollers, but not every direction, just strictly need to pull out from the wall to be able to access the back. So I made legs with bearings as rollers.
In the last week finally put back most of the equipment to it (some not fit, it will be go into the other rack when I'll able to find time to rebuild the back vertical rails.

One of my problems with the rack, how to access the equipment connectors on the back, from the front of the rack. I wanted something modular to be able to put various type of connectors to it.
Built a 1,5U unit onto the top of the previous rack from aluminum extrusion a 3D print. It failed. Wasn't precise enough, won't fit things I wanted to put in.
I was thinking about some Panduit modular patch panels, but never bought it. So just left it.
I put this thing to a side for years.
When I started to build my new rack a few month ago, I just seen something interesting on the net. Asked the owner, what he was using. It turned out, It is a Middle Atlantic Products UCP series modular kit: https://www.legrandav.com/products/accessories/connector_panels/ucp_hinged_frame_kit/ucp-sf
It has two issues for me: It is not on sale in Europe, it uses imperial screws what isn't easy to source here.
I designed and built a 3D printed 3U height modular front panel. It can accommodate 16 modules. It is great, I put it into the rack already, with the breakouts of the four channel HP 6627A power supply.

This could be the final solution, but...
...when it was already built just realized, there exists something called Eurorack Modular Synths. It perfectly match with my ideas. I bought two set of rails.

The 19" rack mount was not included, but by surprise, the original endpieces are already 3D printed

The plan is to design a new endpiece with rack ears.
In the first rack, I'll keep my original design, but in the further rack or racks I'll switch to EuroRack.
In the last few years I was mainly working with Kubernetes. For this I previously built a K3S cluster from 5 Pine A64 SBCs. It broke down (dead SD cards), but I intend to rebuild it.
I thought, it would be a great idea to put these units into the modular front panel. Designed a holder for it.

Didn't print it when the design was ready as my printer had issues, later I didn't find time for it.

To be honest, I done not too much in my electronics project during the summer. The PCBWay asked, if I have problems - absolutely not - and suggested why I don't try out their 3D printing and CNC machining capability.

I was thinking this is a perfect opportunity for this. Made a quotation to this in PETG and some small part in resin. I can tell you, I was shocked. Mainly in the resin prices.
If the things I'm trying to print with a resin printer coming on these prices, absolutely nothing justify keeping my resin printer in the future.
Now the quotation is on. I'll write about the experience and my further way in 3D printing when the printed parts arrive into my hands for inspection.

2023. szeptember 5., kedd

Fluke 787 "Repair"

Big thank you for DuraLeak.

"i purchased this at an estate sale.  i don't know if it works or how to turn it on.  but as it is right now i have pushed every button and nothing comes on the screen.  so because of that i am selling it for parts or repair."

Perfectly working Fluke 787 Processmeter for $143 delivered to Hungary

I need some future tests, but looks ok, for the first sight.

2023. augusztus 27., vasárnap

Dumpster Dive - "woodwork"

A few days ago, I found this nice table frame next to the dumpster.

From the paper box next to it I seen some broken glass, so I suspect it was a glass table before, but the tabletop broken. The owner just thrown it away. Actually it has no issues other than the missing top.
Yesterday I went around the city for some shopping.
Find a 120x70 LDF (not that shitty paper filled crap they mainly sell nowadays) tabletop in the IKEA (it is exactly 15cm larger than the frame in every direction) and bought some aluminum L extrusion in the Bauhaus.
Todays work:

Ooops, a scratch I made while putting it onto the tabletop

I found the function it also - Resin 3D printing and ultrasound cleaning station

Also accommodate some chemicals

and the 3D printer spare parts

Excess paint

And even some free space also left

2023. augusztus 22., kedd


There is some (re)addition to my hobbies.

A few years ago (mainly at the film based era), I was seriously involved in the amateur photography. Went nowhere without an SLR camera. A few years ago, this swept away a bit. There are many reason behind it. I guess the main reason was the better and better cameras in the smart phones.

Anyway, I was never completely satisfied with the performance of it. It was good for documenting my electronics projects but... It was good for my daily needs but...

Then the COVID came. It bring with it a closing down the things. Working in IT with cloud technologies bring almost zero need to go to into an office. My main hobby (still will be) electronics is connected to my lab, what is a closed space. Actually days passed by without going out to the street.

It looks like two and a half year was the limit to me to be able to tolerate this kind of lifestyle. Enough.

So a few weeks ago, I took out my photo equipment from the locker and started to use it. With it, go out to the city, to countryside, just for taking pictures. I love this feeling.

I also plan to move from phone to this equipment also for other photo/video related activities. For this plan, I started to upgrade my set a bit. It doesn't mean buying new equipment. Much more started to collect 2nd hand tools. Added an FX camera (Nikon D610) to be able to utilize the lenses from my film era. Added macro lenses for my object photography goals.

The current set:

My new photography journey starts here.

2023. június 28., szerda

Keithley 2700 - Repair 2.

After some serious issues with the local post, Today the new mains transformer of the 2700 landed in my hands.

So I measured a bit, then installed into the unit.

Actually it was pretty straightforward. Everything connected, assembled.
After some warmup I compared with my 7.5 digit Keithley 2010. It looks like spot on (the Digistant source not really able to keep with them).

2023. június 13., kedd

2023. június 12., hétfő

Reference Resistors

A friend of mine asked me for a quick project (finally it become not so quick, but just because the time it required the parts to arrive).

He is installing pool and other water handling related systems. One of the pool measure system has PT100 temperature sensor input what need calibration. The proper calibration equipment cost a fortune. Actually he only need two reference point. For this he asked me to make some reference resistors in a box what is precise enough and has low tempco.

The values are 100 ohms and 119.4 ohms what is weird a bit. Looked around and find the required resistors in 0603 and 0805 size (100 and 120 ohms 0.01% 2ppm) around $10 each. For the 119.4 ohms I planned 24k in parallel with the 120 ohms (bit less precision as there is not needed better).

I bought some tiny aluminum boxes from the AliExpress. The idea to change the front plate of the boxes to a PCB add the screw-in banana sockets and put the resistors to the back of the boards.

It looks like this:

It was manufactured by PCBWay in the usual excellent quality - Thank you!

I was a bit afraid, if they can follow my request and put the order number to the already crowded component side, but it was managed without problem. It arrived together with my VFD project board, what I'll write about later.

The board soldered (Yes, it is a joke. Only one single resistor in this case)

Some measurements

If I count the cable and the plugs contact resistance is the result get even better. I'm satisfied with the result.

And the final boxes (the request was about two units.

I put two resistance values into a single box. The only thing left is to print some labels on it with the values.