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.
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.
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.
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).
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.
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.
This is part of my readout electronics system. It uses two CMOS 4017 decade counters. The resistors are for current limiting and there are input protection diodes. The reset for both ICs can be triggerd by the small micro button. Speed is fairly moderate, around 5Mhz with required pulse widths of 60ns.
This is part of my readout electronics system. This is a fairly simple ±5V 500mA preamplifier power supply I designed originally with Hamamatsu PMT preamplifiers in mind, but I ended up not getting one of those. So now I’m using it for my own preamplifier modules. The circuit is a fairly standard LM317 and LM337 one with stability improvements by adding a capacitor (and associated diode) to the programming pin. See the data sheets for any LM317 or LM337 for the circuit.
The other day I built this power supply out of components I had lying around. In particular I had this enclosure sitting on the shelf for years now and wanted to finally put it to use and also a toroidal transformer I also had sitting in the shelf. Unfortunately I didn’t take any pictures while building it only after the fact. Here is the schematic, fairly standard and self-explanatory, it uses a 2N3055 transistor and a Zener diode.
I imported this from my old website from way back in time as I just needed it as a reference for myself again. Warning! Everything here is on your own risk. If you don’t know what you are doing DON’T. This is a small step-by-step guide on updating IOS annotated from a script(1) transcript I took from a while back. In my case I’m upgrading IOS 12.1(20)EA1a to IOS 12.1(22)EA14, the latter of which is the last version supporting the Catalyst 2950 series.