DISCLAIMER: AC line (mains) voltage is not something to be taken lightly! Attempting to safely handle line voltages while minimizing the risk of harmful or fatal electric shock is the main motivator for me to design and build this circuit. However, I am no electronics engineer and I definitely have no formal training on international standards pertaining to high-voltage safety. I accept no responsibility, direct or indirect, for any damages that may occur if you attempt to make this circuit yourself, including personal harm or property damage. Additionally, there is no warranty or guarantee, express or implied, on any content pertaining to this blog post (or any other posts).
UPDATE (November 19, 2018): Added isolation voltage ratings for the amplifier and DC-DC converter.
Back in mid-2017 I won a Keysight DSOX1102G digital storage oscilloscope (DSO), a piece of equipment long on my wish list but never acquired until then. One thing I’ve wanted to be able to measure with an oscilloscope for a long time was the waveform of the AC utility (in other words, the wall outlet). However, doing so presents a very real risk of blowing equipment up or shocking yourself (and possibly other people). In order to prevent this, I needed a way to perform measurements on the AC line without being directly connected to it; in other words, I need galvanic isolation. Continue reading →
While on my quest for more eMMC-based storage devices, I stumbled upon a few devices that piqued my interest: eMMC-based SATA SSDs! I found two models of particular interest: Dell had M.2 modules with a 2.5″ adapter, and HP had custom boards intended for use in cheap laptops (for example, the HP 14-an012nr). Although the former was easier for me to use (but not acquire), I will be focusing on the latter in this blog post. Continue reading →
If you haven’t heard of Power over Ethernet, chances are you’ve experienced its usefulness without even knowing about it. Power over Ethernet (PoE for short) does exactly as the name implies: power is sent over the same Ethernet cable normally used for data transfer. This is often used for devices like IP phones and wireless access points (often you see these APs in restaurants and other establishments mounted to the ceiling to provide Wi-Fi access), as it is far easier, cheaper and safer to provide low-voltage power instead of wiring in AC power which requires the help of a licenced electrician.
My ceiling-mounted Ubiquiti UAP-AC-PRO Wi-Fi access point, a typical use case for Power over Ethernet