Reddit:Electronics

I got a big old heavy transformer from a long decommissioned mainframe computer. Around 800-1000VA capable primary and a bunch of single and center-tapped secondaries.

The strong secondary is a center tapped 88V one and I thought I utilize this somehow for my 2x LJM L20 amplifier modules.

Then I recognized I only have 1x fat diode bridge (as 1 package) and a handful of Vishay Hexfred single diodes.

But a classic Graetz bridge would give me +/- 44V rails so I needed a trick - and here it is.

Reversing a classic bridge's 2 diodes on its left side, it gives me 2 positive rails (referenced to ground) which is perfect then for the 2 modules, voltages also just perfect.

This still remains a 2-way rectifier, with a 100Hz pulse cycle (in Europe) and non-magnetizing with respect to the transformer's iron core, retaining great efficiency.

Electronics is great !!

Small project with arduino unosmall project with arduino uno

This pcb includes:

• RP2040 Microcontroller – Dual-core Arm Cortex-M0+ @ 133MHz
• 16MB Flash – Plenty of room for Ducky scripts, firmware, and more
• USB-C & USB-A Ports – Dual USB
• Micro SD Card Slot – Store payloads, logs, or configs externally
• RGB Neopixels – Visual feedback for status, payload execution, etc
• Compact Custom PCB – Designed with portability and DIY hacking in mind

It’s a BadUSB that should act like a keyboard when you plug it in
That means it can type lightning-fast and run commands on a computer just like a human would — but in milliseconds.
here is the repo https://github.com/souptik-samanta/Hackducky
and kicanvas Here

Thank you for reading and every input is appreciated

Apologies for the messy point to point wiring, thats just how I build circuits on this type of board.

The other side has a 20 pin SMD IC soldered to the same wire, and to 2x 10 pin headers, on its own carrier. Turning the chip into a DIP package

My wife spotted a $5 remote control at a Thrift Store/Op Shop so I decided to build Doc Brown's DeLorean remote from Back to the Future (1985). The digits are multiplexed using a 74HC595 shift register but I didn't use a 7-segment BCD display driver because the "6" and "9" digits don't use the top or bottom segments that we are familiar with.

The movie was released on the 3rd of July back in good old 1985.

I went for an induction day at my new college today ( I’m 16 so it’s not as high level as American college).
I followed a schematic and put this together. It’s my first time soldering and studying electronics. Todays been an exciting day

Using aliexpress NE555P i was able to get -78.55% - +99.23% Duty cycle, and 6.666MHz - 6.868MHz at most. Was impossible for me to get so high with a duty cycle around 50/50 so the square waves aren't really square anymore at those speeds. But i'm impressed by how durable and versatile a 53 year old IC can be. Long live the 555 timer! Also my schematic that i came up with and used for this test is found on the last picture, VR1 adjusts duty cycle and VR2 and C1 adjusts frequency. Wrote down my first capacitors and VR2's frequency range. For the higher numbers i changed to 1pf capacitor and different sizez of potentiometers ranging from 2k to 500k Think it was 50k and two 1pf capacitors in series that gave the highest numbers.

These PCB production residues are perfect to store the SMD components like resistors, capacitors and LEDs up to 1206 size. It's much better then stashing the mountains of the old boards.

I really, really love building things. Sure, I could have built this way more compact, without a board at all, but where's the fun in that? 😉

Added a "slightly" bigger capacitor (the red thing) because the old one was ripped of The radio works now again

You can’t hear it, but it sounds beautiful 😍 AI had helped with some issues. Learned A LOT. Gemini told me to add a 1000uf cap to the Bluetooth module bc it kept on disconnecting at high power, and it worked, and I feel like it sounds better now. I’m gonna 3d print a housing and mount them under my desk as conduction speakers. Total project cost was 9 dollars. 1$ Bluetooth board, 2$ amp, and 6$ for 2 3 watt 4 ohm speaker drivers repurposed from a random speaker off eBay.

Powered by a $0.10 RISC V MCU we can do surprisingly accurate whistle detection! Using a timer to make sure whistle sequences are done within a time frame we can do simple whistle pattern recognition for a switch! Great quick project!

I designed a simple board that lets you transmit audio directly from your computer onto the commercial FM band. no code, no drivers, just plug and play.

This was a fun personal project and not meant to be an actual product (you can find similar boards on AliExpress for around $5). It’s also my first ever SMD assembly, and it was pretty fun working with SMD components (SSOP was a bit difficult).

The board uses a TI PCM2704 chip to stream audio over USB from the host device. That audio is then passed to a KT0803 FM transmitter chip, which broadcasts it over FM radio. I added I²C breakout pins, which can be used reprogram the KT0803's settings like transmitting frequency, mode, and calibration parameters.

Github page for the project (Includes the demo with sound) - https://github.com/Outdatedcandy92/FM-Transmitter

I think I salvaged it from an old VCD player. Pretty cool.

Some background here https://antiqueradios.com/forums/viewtopic.php?t=306396

"Prior to the introduction of integrated op amps, it was extremely difficult to build stable DC amplifiers. By passing the signal through a chopper, the DC voltage can be passed through a feedback stabilized AC amplifier and then converted back to DC afterward. Chopper stabilized DC amplifiers--using electromechanical devices--have been around since the late 1940s at least."

"HP's photoconductive choppers eliminated the inevitable problems with contact adjustment and wear in the electromechanical ones, but they required higher input voltages to overcome the "on" resistance of the photocells."

Enjoy!