Sunday, May 28, 2023
Multi-layer reactive foil: no fuel, no oxygen, tons of heat
Sunday, April 9, 2023
Temperature-sensing RFID tag in magnetic stir bar
I describe an old project in which a few friends and I designed an RFID tag that fits into a magnetic stir bar and measures temperature wirelessly. We decided to open-source the project, and you can see the PCB design and tag firmware at the github repo below. I don't think I have the firmware for the base station, unfortunately.
Sunday, January 22, 2023
Identify chemicals with radio frequencies - Nuclear Quadrupole Resonance (MRI without magnets)
How to build and test an NQR spectrometer, which is similar to MRI, but uses no magnets. NQR frequencies are unique among all tested compounds, so detecting a resonance indicates a near certainty that a specific chemical is present.
Tektronix 2-series oscilloscope: https://www.tek.com/en/products/oscilloscopes/2-series-mso Video capture was done via VNC client
Zeeman effect shifting optical spectral lines: https://youtu.be/JV4Fk3VNZqs?t=74
Atomic clock calibration using Zeeman effect: https://www.youtube.com/watch?v=xTy1kY_wtsY
W2AEW's RF tutorial on quarter wave transmission lines: https://www.youtube.com/watch?v=A1BAq0KxIdc
Water deflected by electric field: https://youtu.be/NjLJ77IuBdM?t=468
Litz wire only helpful between 50KHz and 1.5MHz - https://youtu.be/FUCRB9UdfUg?t=2010
Support Applied Science on Patreon: https://www.patreon.com/AppliedScience
Why use vacuum variable capacitors? The parallel LC circuit develops well over 1000 volts during transmit, and they are much easier to finely adjust over a large range.
I've spent quite a few hours making this work since late last year. I failed to detect a signal from urea, which burned dozens of hours. Switching to NaNO2 suddenly produced a huge signal.
NQR calculations spreadsheet - https://docs.google.com/spreadsheets/d/1pkWlgvEXlANemZt3DR1J5g59S7hsejbvs995Y4FRsl0/edit?usp=sharing
NQR references (many!) : https://docs.google.com/document/d/1XoNUhFceH38nSjAFZoxglNiZlUzn6QMxa6CYTyAM92c/edit?usp=sharing
Wednesday, November 23, 2022
How to disable auto updates on Windows 10 Home
I've tried all kinds of things to stop auto updates on Windows 10 Home: Use psexec and disable the items in Task Scheduler, disable the services, run the service as a non-privileged user, edit various registry settings that are intended to influence auto update, try to be creative with "active hours" and play with the clock settings. Nothing that I found on the internet as of Nov 2022 has worked to actually stop the updates. I've found that editing the registry values shown below will definitely stop the updates. As of Nov 2022, this really works. Simply append ".bak" to the listed .dll filenames in the following registry values. You can always change them back. Now reboot or stop the services manually. The scheduler will attempt to start the services as usual, but the system will be unable to find the nonexistent file, and will log error messages that you can see in the System Event Viewer.
If you end up digging into this, there are three things to monitor:
Window Update (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wuauserv)
Windows Update Medic Service (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WaaSMedicSvc)
Windows Update Orchestrator (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsoSvc)
Yes, I know OS updates are important. Sometimes making sure a PC never reboots is even more important. Use your judgement.
These alterations may lengthen boot time (not sure). I have not noticed any other effects.
Thursday, November 3, 2022
How to make precise sheet metal parts (photochemical machining)