#Hardware
Labels Printing Off-Center? Calibrate the Print Offset Once
After getting the label printer to fire its printhead, the next problem was that the text missed the sticker. I stopped guessing and printed rulers and corner markers to measure it, then clearly separated paper size, printable area, and offset into three distinct values.
VM Sees the Dongle but Has No Internet Without a Windows ECM Driver
After passing a USB LTE dongle through to a Windows VM, the system sees the device but no network adapter appears. The cause is neither the SIM nor port passthrough, but the dongle exposing a CDC ECM interface that Windows has no built-in driver for, along with storage-mode pitfalls and dhclient overwriting the host's resolv.conf.
The Monitor That Hammered Devices Until the Whole Farm Went Down
A monitoring loop that runs every 30 seconds and tries to recover every device that fails a ping sounds useful, until one device hangs and gets hammered repeatedly until the whole bus goes down. This article walks through ruling out hardware, tracking what was accessing the devices, and the settings that fixed it.
Reading ID Cards from the Web with a Localhost Agent
Browsers cannot access smart card readers directly. A workable approach is to write a small agent that opens a port on localhost and let the web page call it. This article covers secure contexts, CORS preflight, port conflicts with other agents, PC/SC in SHARED mode, decoding TIS-620 manually, and the day antivirus flagged the program as a backdoor.
Cannot Delete Faces from a Terminal: API Returns notSupport
The door's face recognition terminal advertises a command to delete faces from FDLib, but every variation I tried returned notSupport. People who had left could still scan their faces and get in. This article covers the dead ends, the approach that actually worked using UserInfo/Modify with the smallest possible body, and the two-way user registry sync that runs every night.
Shared Neutrals Across Transformers: Why Phase Balancing Is Not Enough
A case involving two transformers with interconnected neutrals and houses tapped into one side's main feeder, leaving phase A 30-40 A higher even on days off, plus a meter-reading trap that can suggest a 200 A difference if the CT ratio is not verified first, and a repair sequence that must be followed in order.
Sizing Main Cables and Breakers by Installation Method
Notes on choosing the main cable and breaker for a new 253 A feeder, why the same size CV cable can carry 227 A or 364 A depending on how it is installed, and the option of downsizing to 95 and compensating with operating rules, at the cost of the main breaker tripping if anyone breaks those rules.
Diagnosing Feeder Overload from Melted Insulation and Duty Cycles
My investigation of a 95 mm² main cable with insulation melting at scattered points even though the system seemed to work normally, from the nameplates of 6 washers and dryers totaling 234.7 kW to a minute-by-minute current model explaining why a 482 A load on a cable rated for 180 A had not caused a visible system failure.
Tell a Broken Link from an ISP Outage Before Restarting Anything
A typical watchdog restarts NetworkManager when ping fails, which is wrong half the time because no internet access may mean the ISP is down, not that the adapter has failed. This article distinguishes three states using nmcli, then escalates from gentle recovery to PCI remove and rescan without rebooting the machine.
Decoding a Bluetooth Label Printer Protocol from btsnoop
My Bluetooth label printer only had a mobile app and no way to connect it to my own system, so I enabled HCI snoop logging on my own phone, peeled away HCI/ACL/L2CAP/RFCOMM one layer at a time with a short Python parser, and compared the results with open-source libraries until I could read the commands and print directly from a script.
Government ICT Computer Price Criteria + DIY Builds with Scripts
The December 2568 government ICT reference price criteria clearly define specifications for 20,000 baht office computers and 24,000 baht processing computers. In this article, I read the actual criteria item by item, then write a Python script to pull Advice prices and put together DIY builds to compare how much better the value is than buying prebuilt machines.
Read a Toledo RS-232 Scale over Bluetooth with PowerShell
Connect a TWT-01 digital scale with only an RS-232 port to a PC through a BT578 Bluetooth adapter, then read its weight in real time with PowerShell — from Bluetooth pairing and finding the COM port by MAC address to decoding 18-byte Toledo Continuous frames and the null-byte and scale auto-sleep pitfalls I encountered in practice.
USB in WSL2 with usbipd-win — Real Hardware for Linux on Windows
WSL2 cannot see USB devices because it is a VM without a USB controller — usbipd-win passes devices from Windows directly to the WSL kernel with 3 commands, list/bind/attach, plus lessons from actual use: attachments drop when unplugged, the CRLF trap, and USB modems taking over the default route