Maintenance on a Singer Model 347

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So I got this 1960’s Singer Model 347 sewing machine the other day. The motor of the machine was audibly struggling unless on full power, which indicates dried up grease or other high friction going on inside the machine. Who knows how long this had been sitting around unused. So I figured I’ll give it some servicing first before I do anything with it. Getting the manual My first expectation was that I would need to search and track down a scanned manual on the internet.

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Mettler B5 Laboratory Scale (Analytical Balance)

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So recently I acquired this Mettler B5 laboratory scale from back in the 1950s. Unfortunately the manual isn’t available on the internet, or rather I found that someone scanned and uploaded it to a long gone Sendspace link. Fortunately the construction and workings of Mettler scales from that time period are all similar if not the same. Since it is a mechanical balance, it is important for it to be level and situated on a low vibration surface.

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ESP8266 WiFi Temperature and Humidity Monitor

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So recently I needed a temperature and humidity monitor for the basement. I didn’t even look whether there was anything to buy because I knew I had all the parts to quickly build one. And so I did, it’s so embarrassingly simple that it took me less than an hour for everything including firmware. Hardware I used a ESP8266 D1 board, the circuit is super simple, a 15kΩ pullup resistor on the data line of the AM2302 and a LED and associated current limiting 470Ω resistor.

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Benchmarking 1930s Calipers

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So recently I got this set of 1930s calipers: So now the question is: How accurate are they? Let’s find out! I’m using a 25mm micrometer calibration piece, but before we can use it, let’s assess what different instruments say about this piece to get a tolerance range. Note that none of those are professionally calibrated, I’m just doing ballpark measurements. The Micron Metrology micrometer I’m calibrating with this calibration piece says it’s lightly below 25mm, both the instrument and the piece is quite cold however, as I had them in an unheated room and it’s winter.

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Electrical Distribution Panel for my Workshop

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So far my Workshop was connected to a 25A (“L” class) circuit breaker back from the 70s or so and also no FI (RCD). Which isn’t really that safe, especially not in my workshop. Since getting the electrical distribution panel for the house up to standard is currently out of the question, I decided to build myself a sub distribution panel, to at least have a somewhat safe workshop environment.

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Fixing a Microscopy XY Stage (Objektführer)

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On various platforms you can get cheap XY stages (Objektführer) of various designs, because quite often it is hard to get the ones specific to your microscope. I originally got the one on the right for one of my upright microscopes but then noticed it also fits onto my MBS-10 stereomicroscope. However it has the knobs to the side which doesn’t work with the base of the MBS-10. So fair enough I ordered one with knobs on the top (the left one).

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Readout Electronics: High Voltage -1.25kV PMT Bias Supply

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This is part of my readout electronics system. This is an adjustable high voltage power supply I built for biasing the dynodes of photomultiplier tubes (PMTs). It uses a Hamamatsu C4900 high voltage DC-DC converter. Control can either be local (potentiometer on the front panel) or remote (external 5V DAC). The orange LED on the front panel indicates that remote control is active. Whether the unit is in local or remote control is controlled from a microcontroller on an external board.

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Readout Electronics: Wideband Pulse Amplifier

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This is part of my readout electronics system. A high speed amplifier unit I developed a while back, mainly to amplify fast PMT pulses. It uses two uA733 pulse amplifiers with a gain of 20dB, at around 200Mhz with a rise time of 2.5ns. The output of the first one can be inverted with the switch on the front of the unit, which then switches a soviet reed relay (РЗС55А 1101) to select the output.

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