“Arty” LED Patio Light

We have a fairly large patio that was lit by one crummy three-bulb can type fixture. In the evenings the light was horrible – too bright under the fixture and dark everywhere else. The ceiling is also fairly low.

I had an idea of using several LED MR16 bulbs and copper tubing that would be like branches of a tree. This “natural” look also had the convenient advantage of requiring no precise bends ­čÖé

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Minimus 7 Speakers -Terminal Post and Crossover Upgrade

I dug out a pair of the Radio Shack classic mini speakers, Minimus 7s, that I hadn’t used for years. They became part of a major HiFi downsize because, I was forced to admit that our previous speakers were too damn big for the room. One major problem cropped up however. The spring loaded wire clips lost all their “grab”, so the wires wouldn’t stay in. I don’t know if this is a common Minimus 7 problem, but it was pretty bad on these.

I decided to replace the spring clips with binding posts which meant pulling the speakers apart. In the process of looking up how to open the cases up, I stumbled onto articles about upgrading the crossovers, and figured, “Why not?”

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uTracer Vacuum Tube Curve Tracer Build

This post is mostly a shout out to Ronald Dekker, the inventor and seller of a very neat tube tester kit called the uTracer. I did quite a bit of web searching before buying this kit in 2014. It was at that time, and still appears to be, the best device of its kind, especially when you compare to the (high) prices of old tube testers or (you better be sitting down) a Tektronix 570 curve tracer.

I had a large stash of tubes I wanted to sell on eBay. I found that I got much better prices for tested tubes, and in the case of audio power tubes, EVEN BETTER prices if I matched characteristic curves. The uTracer device seems to be, far and away, the best most cost effective device to measure detailed tube data. Buyer’s were very happy when I shipped a curve-trace plot with each tube.

The uTracer is an extremely well thought out design. It is a perfect blend of old and new in that it measured tubes but interfaces to a PC, which provides control and displays the data plots. I won’t go into more detail here, because all is thoroughly explained on the uTracer web site: https://www.dos4ever.com/uTracer3/uTracer3_pag0.html

There are some incredibly slick uTracer builds on the above the site. Mine is pretty bare bones by comparison, but still did it’s job very well.

Recapping Can Capacitors in Antique Electronics

The number one component failure in antique electronic devices is old electrolytic capacitors. Most troublesome are the “can” type multi-segment capacitors. These are hard to find and can be quite expensive. More importantly, even if you find a replacement, it’s likely to be “old stock” and not certain to last since the some aspects of their “clock” started ticking when they were made, not when you start using them.

My approach has been to “re-cap” failed can capacitors with modern capacitors of equal or better ratings. This is cheaper, and also more reliable as long as high quality caps are used. Many think this can’t be done without cutting or damaging the can and impacting the appearance of the equipment. This would, of course, not be desirable in equipment where the can caps are visible, such as old McIntosh power amplifiers.

The rest of this post will show how to re-cap cans so they look completely original when done.

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Philips 212 (GA212) Turntable Upgrade

I still have a Philips 212 turntable that I bought new around 1974. This turntable is a bit of a classic from the heyday of affordable, but high quality, Hi-Fi gear.

Philips 212 turntable. A classic from 1971.

Over the years, my 212 developed all the ailments familiar to owners of these machines. The main power switch failed, and then the touch buttons stopped working. This post details my repair/modification project.

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Renishaw MP11 CNC Probe on a Tormach Mill

There are many CNC touch probes of varying quality available for the Tormach. The two offerings from Tormach are a “passive” probe for about $250, and a “digitizing” probe for $1250. I opted to buy a used Renishaw probe on eBay in an attempt to get the quality and performance of a digitizing probe, but for less than the price of the passive probe.

The cost of used probes on eBay vary all over the map, but I got what I thought was a good deal – a Renishaw MP11 for about $150. My eBay probe came with no cable (more on that later) and had a 1/2″ straight shank, but I figure those shortcomings would not be too hard to rectify.

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MP11 with shop-made TTS adapter

It turned out that my MP11 “deal” was less “great” than I thought because of the “outer diaphragm” issue, which I later found out is common with old Renishaw probes. There are supposed to be two rubber seals that surround the stylus base and keep out dirt while also sealing in some secret oil that prevents corrosion of the contacts. The seals look like tiny gear-shifter boots. They are described (somewhat) in the MP11 manual, starting on page 1-16:

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Adding a VFD to an Odd-Duck Milling Machine (Enco 100-1525) Motor

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Fig 1.VFD box wiring

A while back, I got a nice deal on an early 90’s Enco 100-1525 milling machine. It’s a Chinese 2/3 size Bridgeport copy with an 8″x32″ table. This machine has a 3-phase motor, which I consider a plus because it means I can have knob-controlled speed by adding a VFD (Variable Frequency Drive).

Adding a VFD is usually not too complicated with typical two-speed three-phase motors, but this machine turned out to have a 4.3-to-1 speed ratio between the two ranges (unlike the typical 2-to-1 ratio). With a 2-to-1 ratio, it’s usually fine to run the motor only on the high speed range and then use the VFD for speed reduction. There is a small torque reduction at low speeds when doing this, but for home shop use, it’s fine.

But with the Enco mill motor’s 4.3-to-1 ratio, if I only drive the high speed motor coils and then try to dial down the speed to cover the slow range, the torque loss is too much. This meant I had to┬ákeep BOTH motor speed ranges and devise a way to switch between them.

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Quick and Dirty Combo PC board & Box

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PCB/box combo ready to go after a bit of deburring.

Maybe when you get a new hammer, everything is *not* a nail, but when you have CNC, everything turns into a CNC project ;-). I used to hand-cut a lot lot of copper-clad circuit board material for a variety of projects. It was a quick and dirty way to get stuff built, but cutting PC traces and peeling copper with a hobby knife is slow and hard on your hands.

After needing more than one of this little test box, I turned the board AND box into a quick CNC-cut “kit”, much like model airplane parts.┬á Continue reading

Smartphone Microscope Mount

I needed to get decent images off a microscope in fairly short order. Though I was in a “rush”, it still took a full day to get to a working solution. It is still incredible to me how much time it takes to make something that doesn’t obviously suck.

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Phone mount clamped to eyepiece. Unfortunately I couldn’t show a phone in place because I need my phone to take the shot. The phone mounts between to two cork pads.

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