Scope

We have this old scope for the students. It’s been unused for a while as it behaved erratically and then stopped working completely.

After setting the trigger to a more or less sane value I had something on the screen but the controls where flaky. A heavy dose of our deoxit equivalent and twisting it sprang to life. I adjusted the dc offset (drifts a bit while warming up) and matched the channel gains as much as I could and called it a day.

Fixing a Hitachi V212 oscilloscope

Lamp fixture: done

At least for now. The next step will be adding another support for the roof frame and rollers to guide the ropes around it to unblock the light path should we want to project from there.

Today I hanged the lower frame and then attached the cable trays with a set of bespoke clamps and self tapping screws.

Lamp fixture, metal version.

Today I started to replace that old wooden fixture with another one made of steel.

Our original plan was to install some cable trays to have a more industrial look.

Yesterday I assembled the frames on the floor:

Lamp fixture: metal frames

Today I spent most of the afternoon drilling the wood trusses on the roof and attaching the hooks. Then came the time to lower the old frame and hang the white on those hooks.

Letting it gently go down was easy:

Lamp fixture: dismantling the old one

I used some wire to attach the new frame to the old pulleys and help me lifting it near the roof. That seemed a lot easier on the planning stage but I managed to pull it off in a couple of hours.

To end this day I wound the new rope on the pulleys. Tomorrow I’ll hang the other frame (the black) and screw the trays to it.

Door handle

We have a discrete, and new, metal door but the inner handle is one that was in the house since the 1950’s.

On the outside there’s just a simple knob but it’s not linked to the lock. The handle works as intended but if we are not careful when pulling we end up with it on our hands.

I made a simple plate and kept the rod in place with an M4 screw threaded through it.

Looks like it came with the door:

Door handle

DTMF Remote control and sequencer

Many years ago I built a remote control for our transmitter. It was pretty simple, just a dtmf decoder rescued from an old answering machine.

It served us well for a long time, however it was lost when we moved to a new location.

For the last couple of weeks I spent a while polishing the firmware and making new boards in KiCad. The original was very crude, just a simple on/off panel and delayed power sequence.

This one adds an RF sense and automatic restart, so if one of our amplifiers bails out on a power dropout we don’t have to do anything about it.

Yesterday I etched the boards. I ran out of toner and had to ask a friend to print the transfers. They came horrible but work fine nevertheless.

It’s amazing that nowadays buying an arduino and a preassembled dtmf decoder is cheaper than the single chips (and not counting the time to layout a more complex board).

All the design files are here: https://github.com/fm-futura/dtmf-remote-sequencer

DTMF remote

C Clamp

Just a small Sunday project.

Here at the Uni lab we have a nice articulated lamp that lacks a base. It’s been sitting on a corner for ages so I set to make a new clamp for it.

The frame is just a bit of T beam with a nut and some square tubes welded.

For the handle I used a bit of 3/8 threaded rod and a big washer I had lying around. In order to fix it I decided to make a hole along the axis and tap it to M3. After center punching the rod I screwed it to the drill press, using a center drill to align it. The plan was foiled when I tried to drill, as I left the base loose and it moved. But it’s good enough.

My initial idea was to use another nut and a locking pin behind the front washer but that used up a loot of the available space inside the clamp. After a bit of head scratching I ground a small taper and added a small washer to push the bigger one instead of a nut. I’m quite proud of how it turned out.

Homemade C clamp
Homemade C clamp

Park bench

A while ago we were given a bunch of weathered wood from a deck. Some of us have been thinking of installing seats on the sidewalk and this looked like a good opportunity.

I looked around Core77 and there’s an entry just about seating that produced this helpful guide:

I built a simple frame with square tubing and used one of the wood packs to try it out. I need to select the best planks but it’s comfy and with a bit of paint will look good.

Assorted clamps

The last two days I finished the welds on those clamps,  built some to hold the other end of the ropes and four sturdier to screw to the roof trusses. All the screws are paired with either a nylock or two nuts locked to each other.

I painted the pieces for the bottom frame with black enamel and the ones for the roof with white to match the rest of the room. I know they’ll rust in some weeks but I left the blued surface exposed. I never tire of looking at them.

First run in 20 years.

Today I bought a used battery and decided to crank this old Peugeot 504 to see if the engine was seized or other problems lurked.

It’s been sitting there since 1998 but the diesel in the tank did not smell funny so I used the little pump on the filter until it became hard. On the last strokes I heard a subtle noise and there was a tiny leak on the line.

When connecting the battery there was a small spark and the position lights turned on. I let the glow plugs do their job and tried to crank.

Nothing, just a small click of a relay inside the dash. After a couple of times it turned with some effort but refused to start.

I let the battery rest for a moment and tried again. This time it roared as I pressed the accelerator, puffed some smoke and then idled calmly. I can hardly believe it awoke from a two decade slumber just like that.

Now I have to fix the water circuit (the hoses are dry and crumbling) and the clutch so I can move it around with a bit of ease.

Pouring a concrete floor

That shed I was cleaning needed one thing really bad, a decent floor. It was already made of concrete but with the years it broke down, revealing the soil and gravel underneath. And also wasn’t level.

So for the last couple of weeks we (my dad and I) worked together and made a new one. The next step is adding some tiles on top of that.

Bicycle pulling a car.

This happened today:

That’s a 1981 Peugeot 504 (diesel) that belonged to my grandfather. After his death about 20 years ago it’s been sitting first on the original garage and lately inside this shed that we are fixing up.

The tires have an inner tube as it was usual on that era and that’s an advantage, I doubt that any contemporary tubeless would still be sealed after spending so long being flat.

I had a bit of space to speed up while pushing and the front wheels went by with relative ease. However, there’s a small step and I couldn’t make it go further with the initial momentum alone.

I lifted the car with a jack and made a small ramp out of bricks and a slab of wood. I carefully released the jack and the car slowly moved on its own. The underside looks quite good for a machine of that vintage.

Heavy lift

That hoist was a godsend lately. It helped me move bedroom furniture made of carob and also this old rail that weighs a ton.

During that process both of the galvanized channels I used yielded and I was this close to have everything fall down. But I won at the end.

Lifting a wooden rail

It gets better

I spent most of the last weekend studying and a bit sick.

When not reading for the Uni I binge watched a lot of talks from previous editions of the CppCon, because that’s obviously what only a sick person would do.

And after not being on that scene for quite a while I found that, like for some wines, the time made it nicer.

The use of auto variables when iterating containers, lambdas, parallelization and inclusion of atomic operations (albeit I believe they are insufficiently documented and will bite a lot of people) are just some of the things that surprised me in a good way. There’s a host of cool stuff under <algorithm> and the new optimizations (like the ones carried for constexpr ) are incredible.

Coincidentally, Bert Hubert started a series of posts with the good parts of C++ that actually makes me want to code something in it again.