electronics

I blew out another LED on my wireless charger detector. So I modified it to be simpler, and more interesting.

A few years ago, I realized I had a shoe box with several Raspberry Pi single-board computers just sitting around.

I came across an article saying that interfacing something called a “DHT-11” is a rite of passage for Raspberry Pi users.

I rebuilt my original astable multivibrator with the 2N3904, transistors, better matched capacitors and 10K and 68K Ω resistors from the improved astable multivibrator I wanted to see if that made a difference in the original circuit’s behavior.

I built an “improved” astable multivibrator circuit from:

IMPROVED ASTABLE MULTIVIBRATOR, by RAJU BADDI, National Center for Radio Astrophysics, TIFR, Ganeshkhind P.O Bag 3, Pune University Campus, PUNE 411007, Maharashtra, INDIA; baddi@ncra.tifr.res.in

Here’s the schematic of the improved circuit:

Original astable multivibrator post.

I built an astable multivibrator from discrete components:

I used 2N2222 transistors instead of BCS547.

I built a 3-transistor ring oscillator from discrete components.

In an attempt to gain some electronics knowledge, I bought $30 worth of components and breadboards from Amazon, and built a 2-transistor LED flasher.

I built a Z80-based RC2014 Zed computer from a kit.

I dropped my cell phone and cracked the screen, so I got a Google Pixel 6 and a wireless charging stand. I ended up looking up the “Qi” standard for these chargers. It seemed like the coils used to transfer energy weren’t particularly exotic in size, shape, material or manufacture, so I decided to try to receive some energy from the charging stand.

I’ve since revised this contraption.